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Inspector and Owner

Gain valuable insights on 300+ items to make a sound decision on your investment.

A visual inspection of your condo including major systems not covered by the HOA.

A visual inspection of your townhome including major systems not covered by the HOA. 

Protect your property investment by identifying areas of concerns before you buy.

A visual inspection to assess the condition of the components of your duplex/multiplex.

A visual inspection to assess the condition of the components of your manufactured home.

Gain valuable insights on 300+ items in your new construction home to ensure peace of mind.

Inspect the framing, plumbing, and electrical before the drywall goes up.

Get expert advice without a written report to make a quick, yet informed decision.

List your home confidently by identifying potential issues before the buyer’s inspection.

Assess the progress made on a new construction home to ensure it’s built according to plan.

Customize this service to save on costly repairs and protect your health, safety, and home.

Inspect your home proactively before listing it to identify issues and sell faster.

A thorough inspection of a recently purchased home, giving peace of mind after closing.

Address issues and request repairs with your builder before the warranty expires.

Confirm all the requested repairs have been made from the initial inspection report.

Detect this carcinogenic gas that is the leading cause of lung cancer among nonsmokers.

Detect nitrates, bacteria and other contaminants in tap water that lead to health issues.

Detect harmful indoor allergens and pollutants to breathe easier in your home.

Uncover health and safety hazards hidden in walls and ceilings to avoid costly repairs.

Detect and mitigate clogged or damaged sewer lines before backups in the home occur. 

Ensure the pool and/or spa is functioning properly and free of safety hazards.

Detect mold via air sample to identify the presence of unseen moisture and leaks.

Ensure adequate water flow from the well system to the home. 

Detect asbestos in your home, which was commonly used in building materials before 1980.

Identify lead, prevalent in homes built before 1978, to reduce the risk of health effects.

Identify meth residue to reduce the risk of serious health issues caused by meth exposure.

Inspect the fireplace and chimney to reduce fire hazards like creosote buildup.

Elevate your listing, increase visibility on home selling platforms, and sell faster.

Detect mold via surface sample to protect against health issues and structural damage.

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Colorado has one of the highest radon potentials in the United States. Nearly half of homes tested across the state have radon levels above the [EPA action level of 4 picocuries per liter (pCi/L)](https://cdphe.colorado.gov/hm/radon). 

The reason is Colorado’s natural geology. Some rock and soil formations contain uranium that breaks down over time and releases radon gas. This gas can move through the ground and enter homes through foundation cracks, crawl spaces, sump pits, floor drains, and openings around pipes. 

Radon in Colorado can affect any property, regardless of its age, location, or price. A home may look safe during a walkthrough and still have elevated radon levels that cannot be detected without testing. 

For homeowners and buyers, [radon testing in Colorado](https://wini.com/services/radon-test/) provides valuable information about indoor air quality and helps identify whether additional steps, such as mitigation, may be needed. Whether you are purchasing a home, selling a property, or checking your current home, testing can help you better understand your home’s radon risk. 

## How Common Is Radon in Colorado? 

Radon is common throughout Colorado, and elevated levels can be found in homes across the state. According to [Colorado health officials](https://cdphe.colorado.gov/hm/understanding-radon), about half of Colorado homes have radon levels above the EPA action level of 4 picocuries per liter (pCi/L). 

Colorado’s geology contributes to this risk, with naturally occurring uranium in certain rock and soil formations releasing radon gas over time.  The EPA classifies 53 of Colorado’s 64 counties as Zone 1 areas, meaning they have a high potential for elevated radon levels. 

Radon concerns can be found across many Colorado communities, including Denver, Colorado Springs, Aurora, Fort Collins, Boulder, Lakewood, and Centennial. However, radon levels can vary significantly between properties, even within the same neighborhood. 

Communities along Colorado’s Front Range, including areas near Denver, Boulder, and Colorado Springs, may have higher radon potential due to local geology. However, individual home results can vary based on factors such as foundation design, soil conditions, and construction details. 

## What Is Radon and Why Is It Common in Colorado? 

Radon is a naturally occurring, invisible radioactive gas created when uranium found in certain rocks and soils breaks down over time. Colorado’s geology contains areas with naturally occurring uranium deposits, which can release radon gas as part of this natural process. The gas can move through the soil and enter homes through small openings in the foundation. 

Common entry points for radon in Colorado homes include: 

- Cracks in concrete floors
  
- Foundation gaps
  
- Sump pits
  
- Floor drains
  
- Crawl spaces
  
- Openings around pipes and utilities  

The important thing to understand about radon in Colorado is that any home can have elevated levels. A home's age, location, price, or appearance cannot determine its radon risk.  

## What Are the Symptoms of Radon Exposure? 

Radon exposure does not usually cause noticeable symptoms. Unlike some environmental hazards, you cannot tell if a home has elevated radon levels based on how you feel. A person can feel completely healthy while living in a home with higher radon levels. 

Symptoms such as headaches, nausea, or dizziness are not reliable indicators of radon exposure. The primary health concern comes from long-term exposure, which can increase the risk of developing lung cancer over time. 

## How Does Radon Testing Work in Colorado? 

Radon testing measures the amount of radon in the air inside a home over a specific period. Since radon levels can change based on weather, ventilation, and home conditions, testing helps determine the actual concentration inside a property. 

The length of a radon test depends on the type of test being performed. Short-term radon tests typically run for at least 48 hours, while long-term tests run for more than 90 days and provide a better estimate of a home's average radon levels throughout the year. 

The testing process typically involves: 

Placing an approved radon testing device 
 A licensed radon measurement professional places an approved testing device in an appropriate area of the home, usually at the lowest lived-in level where people spend time.  

- Maintaining proper testing conditions 
 Doors and windows should remain closed as much as possible during the testing period to help capture accurate indoor radon conditions.  

- Allowing the device to collect readings 
 The device remains in place while measuring radon levels inside the home.  

- Completing the test and reviewing results 
 After testing is complete, results are analyzed to determine the home's radon level.  

- Understanding results and next steps 
 Results help homeowners and buyers decide whether additional action, such as mitigation, may be recommended.  

For buyers, the inspection process can provide more information about a home's indoor environment before completing a purchase. A Home Inspection offers professional radon testing as part of its inspection services to help buyers and homeowners better understand potential concerns and make informed decisions. 

## How Do Radon Levels in Colorado Compare to Other States in the US? 

The average indoor radon level in Colorado is approximately 6.4 picocuries per liter (pCi/L), which is higher than the average radon levels in the US, estimated at about 1.3 pCi/L.  

Nearly half of Colorado homes have radon levels above the EPA action level, and radon exposure is linked to more than [500 lung cancer deaths](https://cdphe.colorado.gov/press-release/radon-causes-lung-cancer-test-your-home-0) in the state each year. Colorado’s average indoor radon level has been compared to receiving approximately 200 chest X-rays annually, and the state ranks 45th for the percentage of radon tests exceeding the EPA action level.  

  
![U.S. map showing average indoor radon levels by state, including Colorado at 6.4 pCi/L.](https://d2nnm6ppct4rc3.cloudfront.net/Chat_GPT_Image_Sep_21_2026_11_22_04_PM_8ffcf5154d.png)


[State-by-state comparison](https://www.epa.gov/radon/epa-map-radon-zones) of average indoor radon levels, showing why testing is important even in areas with known radon potential.


## Can Radon Cause Cancer? 

Yes. Long-term exposure to elevated radon levels can increase the risk of lung cancer. Radon breaks down into radioactive particles called radon decay products, which can become trapped in the lungs when inhaled. Over time, these particles can damage lung tissue and increase the chance of developing lung cancer. 

The EPA shows radon as the [second-leading cause of lung cancer in the United States after smoking](https://www.epa.gov/radon/health-risk-radon) and estimates that radon causes approximately 21,000 lung cancer deaths each year nationwide. People who smoke or have smoked face a higher risk because smoking and radon exposure can have a combined effect on lung health. 

## What Should You Do After a High Radon Result? 

A high radon test result does not automatically mean you need to walk away from a home. Instead, it gives you important information that can help you decide what to do next. 

Start by reviewing: 

- The test result 

- Testing conditions 

- The type of test completed 

Whether additional testing is needed 

If elevated radon levels are confirmed, the next steps may include: 

- Reviewing the results and understanding the findings. 

- Contacting a qualified radon professional. 

- Discussing available mitigation options. 

- Completing mitigation work if needed. 

- Testing again after installation to confirm the system is working properly. 

- High radon levels can often be reduced with the right mitigation approach. 

For homebuyers, a high radon result becomes another factor to consider during the inspection period. It does not always mean a deal should end, but it does give buyers the information they need to make a more informed decision. 

## What Should Home Buyers Know About Radon? 

Buying a home involves more than just checking the things you can see. A property may look great during a walkthrough and still have hidden concerns that are not visible without Ftesting. 

Homebuyers should consider: 

- Asking about any previous radon tests 

- Reviewing available test results and reports 

- Checking whether the home has a radon mitigation system 

- Requesting records about any past mitigation work 

- Considering radon testing during the inspection period 

Testing for radon in Colorado gives buyers a clearer understanding of the home's indoor air quality and helps them make a more informed decision before closing. 

## What Can the Colorado Radon Map Tell You? 

A Colorado radon map shows the EPA’s estimated radon potential across different counties in the state. The map classifies counties into three radon potential zones, with Zone 1 representing the highest predicted potential for elevated indoor radon levels, Zone 2 indicating moderate potential, and Zone 3 representing lower potential. 

Colorado has many areas classified as Zone 1 because of geological conditions that can contribute to higher radon potential. However, a radon map only shows general risk patterns and cannot predict the radon level inside a specific home. 



![Colorado map showing radon risk zones by county and potential exposure levels](https://d2nnm6ppct4rc3.cloudfront.net/Chat_GPT_Image_Sep_21_2026_11_26_15_PM_802b542d51.png)


[Colorado radon map](https://www.epa.gov/sites/default/files/2014-08/documents/colorado.pdf) showing estimated risk zones across counties.

Radon in Colorado can vary significantly between properties, even among homes located in the same neighborhood. The only way to understand a home’s actual radon level is through testing. 

 

## What Should Homeowners Do About Radon? 

[Radon](https://wini.com/articles/radon-risks-in-homes/) can be present in any type of home, including properties with no basement or newly built houses. 

A few common assumptions to avoid: 

- A home without a basement cannot have radon 

- Newer homes do not have radon concerns 

- Nearby homes with low results mean your home will have low levels 

It is also a good idea to keep your radon test results for future reference. Consider testing again after major changes to your home, such as: 

- Renovations 

- Foundation work 

- HVAC changes 

- Basement finishing 

- Installation of a radon mitigation system 
 

If your home has a radon mitigation system, regular testing is still recommended. The EPA recommends retesting homes with mitigation systems every two years to confirm the system continues to work effectively. 

## What Happens If Radon Mitigation Is Needed? 

If a home has elevated radon levels, mitigation can help reduce the amount of radon entering the property. 

Most radon mitigation systems use a pipe and fan to collect radon from beneath the foundation and safely vent it outside. Homes with crawl spaces may need more solutions, such as sealed barriers or membranes, depending on design. 

Sealing cracks and openings can help limit radon entry, but it is usually not enough on its own to fully address elevated levels. 

A qualified radon professional can recommend the right mitigation approach based on the home's construction, foundation type, and test results. 

After a mitigation system is installed, a follow-up radon test helps confirm that radon levels have been reduced and the system is working as expected. 

## What Should You Remember About Radon in Colorado? 

Radon can affect any home in Colorado. While the state’s geology creates conditions where elevated levels are common, every property is different and requires testing to understand its actual radon level. 

However, radon levels can vary significantly from one home to another. A home’s neighborhood, price, or construction date cannot determine its radon risk. 

Understanding radon in Colorado is about recognizing that every property is unique and using accurate information to make informed decisions about your home and indoor air quality. 

## Frequently Asked Questions About Radon in Colorado 

### Is radon common in Colorado? 

Yes. Radon in Colorado is a common concern because elevated levels have been found throughout the state. About half of Colorado homes have radon levels above the EPA action level of 4 pCi/L.  

### What radon level is considered high? 

The EPA recommends taking action when radon levels reach 4.0 pCi/L or higher. Homeowners may also consider steps to reduce long-term exposure when levels are between 2.0 and 4.0 pCi/L. 

### Can a home have radon without a basement? 

Yes. A home does not need a basement to have elevated radon levels. Radon can enter properties through cracks, foundation openings, crawl spaces, and gaps around pipes or utilities. 

### How often should you test your home for radon? 

Regular testing can help you understand changes in your home's radon levels over time. Consider testing again after major renovations, foundation work, HVAC changes, or the installation of a radon mitigation system. 

### Can high radon levels be reduced? 

Yes. Elevated radon levels can often be reduced with a properly designed and installed mitigation system. These systems help redirect radon gas from beneath the home and vent it safely outside. 

### Do new homes in Colorado have radon? 

Yes. Newer homes can have elevated radon levels because radon can enter through foundation openings, cracks, and utility penetrations. Home age alone does not determine whether a property has radon. 

### Is radon testing required when buying a home in Colorado? 

Colorado does not require every home purchase to include a radon test. However, state law requires residential sellers to provide a radon warning and disclosure information during the sale process. This includes information about any known radon test results, mitigation systems, and related records, along with the current Colorado Department of Public Health and Environment (CDPHE) radon brochure. 

Many buyers still choose to complete professional radon testing during the inspection period because disclosure information may not reflect the home's current radon levels. 

### How long does a radon test take in Colorado? 

A short-term radon test typically takes at least 48 hours to complete. Long-term tests run for more than 90 days and provide a better picture of average radon levels over time. The right testing method depends on whether you are buying a home, monitoring an existing property, or checking the effectiveness of a mitigation system.

Radon in Colorado: What Every Homeowner and Buyer Should Know

You find the perfect house, and the backyard has a cute little rental unit that could cover part of your mortgage every month. Then you learn something that stops you cold. One peer-reviewed study found that 78.2% of the detached backyard units built in San José between 2016 and 2020 were never permitted. That little income machine could quietly become your biggest headache the day you get the keys. 

So the real question with any backyard unit comes down to this. Is this ADU legal, and if it is not, what will fixing it cost you? An unpermitted or poorly built unit can freeze your loan, get an insurance claim denied, come up short on the appraisal, and land on you as a brand new liability. By the end of this guide you will know what to check, what it costs, and when you should just walk away. 

## What Is an ADU? 

ADU stands for accessory dwelling unit. In plain words, it is a small second home that sits on the same lot as a regular single family house. It has its own kitchen, its own bathroom, a place to sleep, and its own door to the outside. It is always the smaller of the two homes on the property. 

People call these units by a whole pile of names, which is part of why they are so hard to track. You might hear granny flat, granny unit, in-law suite, mother-in-law suite, casita, secondary suite, garage apartment, backyard cottage, carriage house, or just second unit. When one was built without permits, folks sometimes call it "shadow housing." 

## Types of ADUs 

The type of unit tells you a lot about how much risk you are taking on. 
![Types of ADU's In United States](https://d2nnm6ppct4rc3.cloudfront.net/Types_of_ADU_s_In_United_States_61a79739c0.png)

## Why ADUs Are Booming (and Why That Is a Buyer's Problem) 

Backyard units are showing up everywhere now. Freddie Mac counted about 1.4 million US properties with an ADU. In California the growth has been wild. The state went from 1,336 ADU permits in 2016 to 26,924 in 2023, and by that year ADUs made up more than a fifth of every home permitted across the whole state. 

Here is the part that should make a buyer sit up. A 2023 Freddie Mac survey found that 71% of people did not really know what an ADU was, and about a third got interested once they learned. So the market is huge, it is growing fast, and most of it is undocumented. That means the job of checking whether a unit is actually legal lands on you, the buyer. 

## Why an ADU Inspection Is Not a Normal Home Inspection 

Here is the mistake most people make. They treat the backyard unit as a fun bonus feature stapled onto the main house. Please do not do that. Treat the ADU as a second home inspection all by itself. It has its own electrical, its own plumbing, its own heating, and its own list of problems, and its condition is often very different from the main house next to it. 

A regular home inspection follows the ASHI Standards of Practice, which is a solid baseline. But a generic inspector may skip the things that matter most for a second unit. That includes whether the electrical is truly separate, whether there is proper fire separation between attached units, whether the heating and plumbing stand on their own, and whether the permits and Certificate of Occupancy really exist. Knowing local ADU code is what separates a real ADU inspection from a lazy one. 

![Difference Between ADU Inspection & Standard Home Inspection.png](https://d2nnm6ppct4rc3.cloudfront.net/Difference_Between_ADU_Inspection_and_Standard_Home_Inspection_861760acb7.png)

## Permitted vs. Unpermitted: The Detail That Matters Most 

If you remember one thing from this whole article, make it this part. Permit status is the single most important detail in any deal with a backyard unit. It matters more than any crack in the wall or old water heater you might spot. 

### The "Open Permit" Trap 

Here is the trap almost nobody warns you about. A permit that was pulled but never signed off, called an "open permit," gets treated exactly like no permit at all by lenders, insurers, and title companies. Inspectors run into this constantly. The owner paid the fees, a contractor pulled the permit, and then nobody ever came back for the final sign-off. So you have to check the actual status, not just whether some permit exists on paper. 

### How to Check a Permit Yourself 

You can do most of this before you even make an offer. 

- Search the city or county building department permit portal. Places like LADBS, Seattle SDCI, Portland, and Honolulu DPP all have one online. 
- Look for "Final" status or "Certificate of Occupancy Issued." Do not settle for "Permit Issued" or "Approved," because those words do not mean the work actually passed. 
- Use the real building records, not the tax or assessor data. Portland even warns people not to trust tax info for this. 
- Compare the approved plans to what is really standing there, and make sure the unit count on record matches what you see with your own eyes. 

### What Happens If It Was Never Permitted 

An unpermitted unit can hit you in several ways at once. 

- Many California cities charge up to $1,000 a day until it is resolved. Seattle goes up to $500 a day, plus stop-work orders and even forced removal. 
- Lenders may refuse, and unpermitted square footage cannot count as living space, so the appraisal may fall short of your loan. 
- Carriers may deny coverage for a structure that was never permitted or inspected. 
- You will get lower offers, you must disclose it, and hiding it can bring fraud liability. 

And enforcement is climbing. In LA County, ADU code-violation cases jumped from 16 a year in 2018 to 53 a year in 2023, which is a 230% surge. 

## What an ADU Inspection Actually Covers 

This is the real meat of the job. A good inspector goes system by system. Here is what they look at and why each one can bite you. 

### The structure and foundation: 
Foundations should reach deep enough to be safe. In the City of LA, that means at least 12 inches below grade. Old garage slabs often skip the moisture barrier and sit too shallow for a real home. Rotted wood or weak beams can quietly turn a conversion into a teardown. 

### Electrical: 
This is one of the biggest problem areas by far. The unit's circuits must be fully separate from the main house, and all new circuits need AFCI protection. An old garage was wired for a single 20-amp circuit to run a light and a door opener, which cannot power a real home with a kitchen and heat. Most units need at least a 100-amp subpanel, and that upgrade runs about $2,000 to $5,000. 

### Plumbing, sewer, and septic: 
Most ADUs tie into the main home's sewer line. Ask for a sewer scope, which costs about $200 to $500 and can save you from a truly nasty surprise. A new sewer lateral can run $5,000 to $15,000, and septic work can climb even higher. Water pressure should stay at or below 80 PSI. 

### HVAC: 
A detached unit needs its own heating, cooling, and hot water. Small systems get worked hard, and a sloppy install fails fast once winter hits. 

### Roof, insulation, and airflow: 
Garage walls are often too thin for the insulation the code wants. If there is no ventilation system at all, that is a bright red flag for an illegal conversion. 

### Doors, windows, and escape: 
The main door should be at least 36 inches wide and 80 inches tall and open straight to the outside. Every bedroom needs an escape window big enough to climb out of during a fire. Living spaces need ceilings at least 7 feet high, which trips up a lot of basement conversions. 

### Fire safety: 
Attached units usually need a 1-hour fire-rated wall and ceiling between the two homes, plus smoke and CO alarms that talk to each other. The 2024 code adds some flexibility when both units' alarms trigger together. 

### Sound: 
Shared walls and floors are supposed to block noise to a set standard. Thin walls are one of the most common complaints inspectors and tenants report. 

### Moisture and water drainage: 
Small units have almost no room for error. Poor grading, missing vapor barriers, and old water damage all tend to show up here. 

## Garage-Conversion Red Flags 

Garage conversions are the trickiest type, so learn to spot the tells yourself before your inspector even shows up. Keep an eye out for these signs. 

- A garage that no longer looks like a garage, with finished walls, carpet, recessed lights, a fridge, or a closet. 
- More rooms than the older Zillow or Redfin photos showed. 
- A small backyard building that has power, plumbing, AC, and a bed inside. 
- Electrical that clearly does not match the rest of the house. 
- No ventilation, plus cheap or sloppy workmanship. 

Why are they so risky? Garages usually have weak electrical, thin walls, no slab moisture barrier, shallow foundations, floors that slope toward the old garage door, and low ceilings. On top of that, the covered parking is gone, and the permits are often missing. 

## What It Costs: Inspection, Repairs, and Legalization 

Here is the good news and the bad news at the same time. Checking a unit is cheap, but fixing one is not. 

A standard home inspection averages about $343 nationally, with most falling between $296 and $424. A home with an ADU is basically two inspections, so plan on roughly $200 more per unit, plus any add-ons like a sewer scope. The whole visit takes 2 to 4 hours, and you usually get the report within a day. 

Now for the repairs. 

![What It Costs Inspection, Repairs, and Legalization of the ADU.png](https://d2nnm6ppct4rc3.cloudfront.net/What_It_Costs_Inspection_Repairs_and_Legalization_of_the_ADU_b22db4b2a1.png)

And here comes the big one. Making an unpermitted unit legal usually costs $25,000 to $60,000 for a clean but noncompliant unit. It can start around $10,000 and climb past $120,000 when there are major code gaps. Retroactive permit fees often run 2 to 3 times the normal rate. 

So sit with that math for a second. A $343 inspection can flag a $60,000 problem before you ever sign a thing. That really is the cheapest insurance in the whole deal. 

## Financing, Appraisal, and Insurance 
This part changed a lot recently, so pay close attention to the dates. None of this is financial or legal advice, so always confirm the details with your own lender and agent. 

### Financing: 
As of early 2026, Fannie Mae (in announcement SEL-2025-08), Freddie Mac, and FHA all let you count ADU rental income toward qualifying for a loan on an eligible one-unit primary home. The common rule is about 75% of the rent, capped near 30% of your total income. These rules shift often, so check the current numbers with a lender before you count on them. 

### Appraisal: 
To count that ADU income, appraisers use a form called the 1007, and they weigh things like separate meters, a separate address, and whether the unit can legally be rented. The FHFA began adding ADU data to its appraisal dataset back in 2023. 

### Insurance: 
This is the gap that catches so many people off guard. A detached ADU usually falls under "other structures" on your policy, which is often only about 10% of your dwelling coverage. 

Say your home is insured for $350,000. Your detached backyard unit might be capped at only about $35,000. But rebuilding that unit could easily cost more than $150,000. That leaves a six-figure hole you did not even know you had. 

If you rent it out, you need a separate landlord policy. And an unpermitted unit can get a claim denied outright, which turns a bad day into a financial disaster. 

## Codes and State Laws, Kept Simple 

Codes shift by state and city, so here is the short version. The International Residential Code is adopted in 49 of the 50 states, though the exact edition and local tweaks vary. The strongest ADU laws live in California, Washington, Oregon, and Colorado, and more than 20 states now have statewide ADU rules on the books. 

A few fresh examples worth knowing: 
- California passed AB 1154 and SB 543, both taking effect in 2026. 
- California AB 2533 lets owners legalize many units built before 2020 without a big penalty. 
- Washington's HB 1337 allows 2 ADUs per lot and dropped its owner-occupancy rule. 

One rule never changes, no matter where you live. Always confirm with your local planning department. State law cannot capture your exact lot, its setbacks, its utility limits, or your HOA rules. 

## Your Action Plan: Before, During, and After 

Break the whole thing into three simple stages. 

### Before the inspection day: 
Pull the permit history, the final inspection or Certificate of Occupancy, and the seller's disclosure. Do this early, before your inspection contingency runs out. Compare the current listing photos to older ones online to catch any rooms that got quietly added. 

### During the inspection visit: 
Show up in person if you can. Make the inspector walk the ADU's own systems with you, checking electrical independence, fire separation, escape windows, heating, and the sewer or septic tie-in. 

### After the inspection wraps: 
Go over the findings with your agent. Get real repair and legalization estimates. Call your insurance carrier to confirm you can actually cover the unit. Then you can negotiate credits, ask for repairs, or walk away while you still hold some leverage. 

## How to Pick an ADU Inspector 

Ask a few pointed questions before you hire anyone. Are they certified by ASHI or InterNACHI? Do they carry errors and omissions insurance? Have they completed 500 or more inspections? Do they actually know local ADU code? Will they inspect the ADU as its own unit, research the permit history, and check the sewer lateral or septic? A confident yes to those is exactly what you want to hear. 

## Key Takeaways 

Three ideas are worth carrying with you into any deal. 

First, permits matter more than anything else, so confirm the "Final" status, not just the paperwork sitting in a folder. 
Second, treat the backyard unit as a second inspection with its own systems and its own risks. 
Third, it is cheap to check and expensive to fix, so a few hundred dollars today can catch a five-figure problem tomorrow. 

Ready to move forward with confidence? Book an inspection with someone who truly knows ADUs, and grab a free ADU inspection and permit-verification checklist so nothing slips past you. 

## Frequently Asked Questions 

### Ques 1: Do I need a separate inspection for an ADU? 
Ans 1: Yes. It runs on its own systems, so it should be checked as its own home, not as a tiny footnote to the main house. 

### Ques 2: How do I check if an ADU was permitted?
Ans 2: Search your city or county permit portal for the building permit and the final inspection or Certificate of Occupancy. Remember that an open permit counts as no permit. 

### Ques 3: Will my homeowner's insurance cover a detached ADU?
Ans 3: Usually only about 10% of your dwelling coverage, which is often way below the rebuild cost. You will likely need extra coverage, and a rental needs its own landlord policy. 

### Ques 4: Can I convert my garage to an ADU without a permit?
Ans 4: No. It risks fines, denied insurance, and big problems when you try to sell or refinance later on. 

### Ques 5: Can ADU rental income help me qualify for a mortgage? 
Ans 5: As of 2025 and 2026, often yes. Lenders may count about 75% of the rent, capped near 30% of your income. Confirm the current rules with your lender. 

### Ques 6: I am buying a home with an unpermitted ADU, so what to do now?
Ans 6: Get it inspected, confirm you can insure it, price out legalization or removal, talk to the building department and a contractor, then renegotiate, legalize, or walk. 

### Ques 7: How long does an inspection take and what does it cost? 
Ans 7: Around 2 to 4 hours, and roughly $343, plus about $200 per unit and any add-ons like a sewer scope.

ADU Home Inspection: What Homeowners Should Know About Backyard Units 

At first glance, the condo vs coop decision can feel like a matter of preference. One building has a doorman. Another has a rooftop. Maybe both units have similar layouts, similar square footage, and even similar asking prices. Yet what you are actually buying can be completely different.

That difference starts to matter long before move-in day. It can affect how you finance the purchase, what you pay each month, whether you can renovate the kitchen, how easily you can rent the unit later, and even what happens when you eventually decide to sell. So before comparing countertops and floor plans, it helps to understand what separates a condo from a co-op in the first place.

## How Is a Condo Different From a Co-op?

A condo and a co-op can look almost identical during a showing, but what you are buying is not the same. With a [condo](https://wini.com/services/condo-inspection/), or condominium, the unit belongs to you as real estate and the ownership is recorded through a deed.. The lobby, hallways and other shared parts of the property are handled collectively through the building’s association.

A co-op, short for housing cooperative, takes a less direct route. The building is owned by a corporation, and your purchase is for shares connected to the apartment you will live in. That difference tends to show up later, especially when it comes to financing, board approval, making changes to the unit, renting it out or selling your interest.

## Key Differences Between Condos and Co-ops

![Condo vs. co-op comparison showing ownership, financing, buyer review, renting, and monthly costs](https://d2nnm6ppct4rc3.cloudfront.net/condo_vs_co_op_comparison_f4caf46f13.jpg)

The difference goes well beyond who holds the deed. Financing, monthly payments, building rules and the approval process can all work differently depending on what you buy. Condo buyers usually deal with a mortgage on the unit and pay association dues for shared expenses. In a co-op, financing is tied to the shares being purchased, while monthly maintenance may cover a broader mix of building costs.

The day-to-day experience can differ too. A condo association may set rules around pets, rentals or renovations, but co-op boards often have a bigger role in those decisions. Some may review buyers before a sale goes through or require approval before an apartment is rented or significantly changed. Those details vary from one building to another, which is why the documents for the property matter more than assumptions about how condos or co-ops usually work.

## How Does Financing Differ for a Condo and a Co-op?

Financing a condo usually feels closer to buying a traditional home. The loan is tied to the unit itself, although the lender may also review the building before moving forward. That review can include things such as the association’s finances, insurance, or other requirements connected with the property, so approval may depend on more than the buyer’s personal finances.

A co-op takes a different route because there is no individually deeded apartment securing the loan. Buyers commonly finance the shares they are purchasing instead, which means working with a lender that handles co-op loans. The building may also have its own financial requirements for buyers. If a co-op is on your shortlist, it can help to talk with a lender familiar with this type of purchase early rather than waiting until you are ready to make an offer.

## Pros and Cons of Buying a Condo

A condo can feel more familiar to buyers because the unit is owned directly, but that does not mean every building works the same way. The benefits usually come down to ownership, financing, and flexibility, while the drawbacks tend to sit with association rules and shared building costs.

### Pros:

- Condo ownership: A condo gives you ownership of the individual property, with that ownership recorded through a deed.
- Condo financing: Financing is usually easier to find for condos than for co-ops, though lenders can still look at the building before approving the loan.
- Rental flexibility: Depending on the association, owners may have more freedom when it comes to renting the unit, making changes, or selling later.
- Shared maintenance: Things outside the unit, such as shared hallways, exterior spaces, and other building features, are generally looked after through the association.

### Cons:

- HOA fees: Condo owners usually pay regular association dues, and those costs can rise when the building’s expenses increase.
- Association rules: Pets, rentals, renovations, parking, and even how certain parts of the unit are used may come with restrictions set by the association.
- Special assessments: If the building needs a major repair or improvement and reserves are not enough, owners may be asked to contribute an additional amount.
- Shared decisions: Some choices about the property are made at the association level, which means owners do not always have the final say on building-wide changes.

## Pros and Cons of Buying a Co-op

A co-op can work well for buyers who are comfortable with a more structured building setup. The trade-off is that you are not just buying into a home, you are also buying into the way that particular corporation is run.

### Pros:

- Purchase price: In some markets, co-ops may be priced below comparable condos, which can make certain buildings or neighborhoods more accessible.
- Resident involvement: Shareholders can have a stronger voice in decisions about how the property is managed.
- Shared expenses: Monthly maintenance may bundle together several building-related costs that condo owners could otherwise see separately.
- Building oversight: Some buyers prefer a property where purchases, rentals, and major changes are reviewed more closely.

### Cons:

- Board approval: Expect a closer look at the purchase. Financial documents, references, and other information may be part of the process.
- Co-op financing: Fewer lenders may handle share loans, so financing can take a little more planning than a standard condo purchase.
- Rental restrictions: Subletting may be limited, subject to approval, or restricted by the building altogether.
- Resale process: When you decide to sell, the next buyer may also need to meet the co-op’s requirements before the transfer can move forward.

## Who Handles Maintenance and Repairs in a Condo or Co-op?

This is where the lines can get a little less obvious. In a condo, owners usually take care of what is inside their unit, while the association handles shared spaces and certain building systems. But something as simple as a leaking pipe or damaged window can become a question of responsibility depending on where the issue starts and how the building documents define it.

A co-op can be just as specific. The corporation owns the building, but shareholders may still be responsible for parts of the apartment they occupy. Before buying, it is worth checking who handles repairs, replacements and ongoing upkeep, especially for items that sit somewhere between the unit and the larger building.

## How to Decide Between a Condo and a Co-op

Start with what you may actually want to do with the place. You might love the unit today, but what if you want to rent it out in a few years, redo the kitchen, or sell sooner than planned? A condo can leave more room for some of those choices, depending on the association. With a co-op, you will want to be comfortable with the board having a bigger role and with the rules that come with that particular building.

Price can push the decision one way or the other, but don't stop at the number on the listing. Put the monthly charges, financing, possible assessments, and rules around renting or renovations next to each other. A lower-priced co-op can still be the better buy for one home buyer, while someone else may be willing to pay more for the flexibility a condo offers. The better fit is the one that still makes sense after you look beyond the apartment itself.

### Does a Condo or Co-op Need a Home Inspection?

It can be easy to assume that buying in a shared building means most property concerns fall to the association or co-op. That is not always the case. There can still be plenty happening inside the unit itself, from plumbing and electrical components to heating and cooling equipment, appliances, windows, doors, walls, and other accessible areas.

For a home buyer, an inspection offers a closer look at the space before closing. Homeowners may use one later to keep track of how systems and components are holding up, while home sellers may want a better idea of the unit’s condition before putting it on the market. At [WIN Home Inspection](https://wini.com/), a condo inspection focuses on accessible areas within the unit and major systems that may not be covered by the association.

The building paperwork still matters. A roof, exterior wall, shared plumbing line, central system, or common area may be handled by the association or co-op rather than the person living in the unit. Looking at the inspection findings alongside the governing documents can make it much clearer where the unit ends and the building’s responsibility begins.

## Frequently Asked Questions 

### Which is better, a co-op or a condo?

Neither one is automatically better. A condo may appeal more to someone who wants deeded ownership and more flexibility around renting, renovating, or selling. A co-op can work well for a buyer who is comfortable with board involvement and finds a building whose price, monthly costs, and rules fit their plans.

### Why can co-ops be cheaper than condos?

Co-ops may have lower asking prices than similar condos in some markets. Tighter approval requirements, fewer financing options, restrictions on subletting, and differences in buyer demand can all play a part. The lower purchase price does not always mean lower overall costs, though, since maintenance charges and other building expenses also need to be considered.

### What is the downside of buying a co-op?

For some buyers, the biggest drawback is having less flexibility. The purchase may involve a detailed board review, and the building can have rules around renovations, subletting, pets, or other changes. Co-op financing can also require a lender familiar with this type of ownership.

### Can you rent out a condo or co-op?

It depends on the building. Condo associations may allow rentals but still set limits on lease terms or the number of units that can be rented. Co-ops often have tighter subletting rules and may require board approval before someone else can occupy the unit.

### What is the role of the board in a co-op versus a condo?

A co-op board can have a larger role in the purchase process and may review prospective shareholders before approving a sale. Condo associations also manage common areas and enforce building rules, but they generally have less involvement in approving who purchases an individual unit.

### Can you renovate a condo or co-op?

Renovations may be possible in both, but the rules can be different. Condo owners still need to follow association requirements, especially when work affects shared systems or parts of the building. In a co-op, certain changes may need approval from the board before the work begins.

Condo vs. Co-op: Key Differences, Pros and Cons

Do you know when your air filter was last changed? Most people don't, and that's normal, it's easy to overlook. But it's worth checking, because a fresh filter makes a real difference: rooms feel more comfortable, dust stays away longer after you clean, and your HVAC doesn't have to work as hard to keep up. If you just bought the house, learning how to change your air filter is a good place to start. 

According to the [U.S. Department of Energy](https://www.energy.gov/sites/default/files/2016/11/f34/HomeCooling101.pdf?), replacing a clogged filter can reduce an air conditioner’s energy use by 5% to 15%. For a homebuyer, a heavily coated filter may raise questions about how consistently the HVAC system was maintained. 

Changing the filter is usually simple. Finding it, choosing the right size, and pointing the airflow arrow correctly can be less obvious. This guide and the short video below walk you through each step. 
 

## Why Regular Air Filter Replacement Matters 

Your heating and cooling system keeps pulling household air back through its equipment. The filter sits in that return path and catches the everyday mess moving with it: dust, lint, pet hair, and other small particles. 

A dryer lint screen offers a useful comparison. A light coating is normal. Leave it too long and the open surface disappears under a gray mat. The same thing happens here. Once dirt fills the filter, the fan has less open material to pull air through. You may notice weaker vents first. Or one room that never quite catches up. 

There is a limit to what a new filter can do. It won't seal a loose duct, fix a weak fan, or solve every air-quality concern. What it can do is support airflow, [reduce indoor air pollutants](https://wini.com/articles/reducing-indoor-air-pollutants-with-air-filters/) and keep some debris away from the equipment. 

## What You Need to Do to Change an Air Filter 

This is a short-tool-list job. Set the new filter nearby, open a bag for the old one, and have a cloth or vacuum ready for the edge of the slot. 

Compare the labels before opening the new filter. A 16 x 20 x 1 filter is not interchangeable with the closest-looking box. If the print is faint, take a photo and zoom in. 

- A replacement with the same printed size and approved type 

- A marker or phone reminder for the date 

- A bag for the dusty filter 

- A dry cloth or vacuum 

- A screwdriver or stable step stool, if needed 

- The equipment manual, if anything is unclear 

## How to Change Air Filter in House: Six Steps 

Here are a few steps to change your air filter at home:  

### Step 1: Turn Off the HVAC System  

Set the thermostat to Off, then wait until the fan stops. Don't rush this part. With the fan running, loose dust can be pulled through the empty slot. Your unit may also have a service switch, or its manual may call for the breaker to be turned off before opening a cover. Follow the directions on that equipment. 

If access exposes wiring, sharp metal, or moving parts, close the panel and call a professional. That is no longer a routine filter change.  

### Step 2: Locate the HVAC Air Filter  

Start beside the furnace or indoor air handler - the indoor cabinet that contains the fan and cooling parts. Look for a narrow slot where the return duct meets the cabinet. It may have a small cover. A thick filter usually sits inside a wider, obvious cabinet of its own. 

No filter beside the unit? Look behind the large grilles on the walls or ceiling. Those are often return grilles, which pull room air back toward the equipment. The filter may be sitting right behind one. And take a slow walk through the house. Two systems usually mean two filters; some homes have several filtered returns. 

### Step 3: Check the Filter Size and Type  

Read the numbers on the frame. They usually appear as length x width x thickness, such as 16 x 20 x 1. Buy that printed size. The actual filter may measure a little smaller because box sizes are often rounded. Copy the label rather than rounding your own measurement. 

Check the type too. Most thin fiberglass and pleated filters are disposable; reusable filters say so on the frame. Note the MERV number if one is printed. We will explain that rating later. For now, the safest choice is to match what the system already uses. In any how to change air filter guide, matching the printed size matters more than rounding a measurement. 

### Step 4: How to Replace an Air Filter Safely 

Before you pull anything out, take a photo. Get the old arrow and the edge of the slot in the frame. Yes, it can feel unnecessary. Then the old filter is on the floor, the new one is in your hand, and both directions somehow look correct. These are also the basic steps for how to replace the air filter safely without spreading dust through the house. 

Pull the filter out slowly and bag it if it is heavily coated. Wipe or vacuum the accessible rim of the slot, but do not reach into the cabinet. 

### Step 5: Install the New AC Air Filter in the Correct Direction 

Find the airflow arrow on the new filter and point it toward the equipment. Behind a return grille, that usually means away from the room and into the duct. If the layout makes you pause, use the photo you took. That was the point of taking it. 

Ease the filter into the track. It should slide in and sit flat. If the frame bends, pull it out, check the size and wrapper, then line it up again. Don't force it. 

### Step 6: Complete the Air Filter Replacement  

Put the grille or cover back before restoring the power. Then return the thermostat to its normal setting and listen. A new whistle may mean the filter is sitting crooked, the cover is loose, or the filter is too restrictive. A rattle deserves another look as well. 

Before you walk away, write the date on the frame. Save the size of your phone, too. It takes ten seconds now and avoids standing in a store later, staring at a row of nearly identical boxes. You have now completed the core how to change air filter process. 

  
![Infographic showing how to change an HVAC filter in six steps, from turning off the system to installing the filter and restarting it](https://d2nnm6ppct4rc3.cloudfront.net/how_to_change_hvac_filter_6_steps_exact_logo_c7c1f04b41.png)

At a glance: Switch the system off. Find the filter and note its size, type, and arrow direction. Ease the old filter out, clean the edge of the opening, and slide the matching replacement in with its arrow pointing toward the equipment. Close the cover before turning the system back on. If you are asking, “how do you change the air filter?” use this how to change air filter checklist as your quick reference.  

 

## Which Direction Should an HVAC Air Filter Face? 

The one rule: Point the airflow arrow toward the furnace, air handler, or blower. For a filter behind a return grille, the arrow usually points away from the room and into the duct. 

 

Many filters have a support grid on the side facing the equipment. It helps the material hold its shape while the fan pulls air through. Install it backward and the filter may bow. If the old arrow has faded, look for one on the cabinet or check the manual. A guess saves a few seconds and can create a second trip back to the filter. 

## How Often Should You Change an Air Conditioner Filter? 

A one-inch disposable filter may need replacing every one to three months, but that range is only a starting point. Check it monthly during periods of heavy heating or cooling. [ENERGY STAR](https://www.energystar.gov/saveathome/heating-cooling?) also recommends regular filter checks when the HVAC system is working harder. 

Your household conditions determine the actual schedule. Pets, smoke, renovation dust, nearby construction, and long fan run times can clog a filter sooner. Thicker filters may last longer, but they still need to be checked. 

If you recently moved into a home, inspect the filter monthly for the first season. This will help you learn how quickly it collects debris under normal use. Knowing when to check the filter matters just as much as knowing how to replace it. For additional seasonal care, follow these steps to [maintain your air conditioner](https://wini.com/articles/3-easy-steps-to-maintain-your-air-conditioner-this-summer/). 

![Table showing how often to check HVAC filters based on filter type and household conditions](https://d2nnm6ppct4rc3.cloudfront.net/filter_check_schedule_exact_logo_6f18af6bfc.png)

## How Can You Tell If an HVAC Filter Needs Replacing? 

Take the filter somewhere with good light. A little gray is normal, but dust and hair packed across the surface may mean it is time for a replacement. If you are unsure, compare it with a clean filter. The difference is usually easy to see. During a [4-point inspection](https://wini.com/services/four-point-inspection/), the inspector also reviews the HVAC system’s visible condition and may note concerns that need further evaluation. 

The house may offer other clues. None proves that the filter is clogged, but several together make it worth checking: 

- Several vents feel weaker than usual.  

- Rooms remain uneven during long HVAC cycles.  

- Dust returns soon after cleaning.  

- The filter has bowed, torn, or pulled away from its frame.  

- A musty odor appears near the return or equipment.  

- The recommended replacement period has passed. 

Do not ignore moisture: A damp filter is not simply a dirty filter. Replace it, then look for the source of water or condensation. Repeated dampness, staining, or visible growth around the equipment should be assessed by a qualified professional. 

 

## How to Choose the Right Air Filter Replacement 

A dependable on how to change air filter routine starts with a replacement that fits the slot and suits the equipment. 

### Match the Filter Dimensions 

Copy all three numbers from the old frame. Don't round them. A small filter leaves room for air to slip around the edges; a large one can bend or jam. If the old filter is missing, the equipment label or manual is a better guide than a tape measure and a guess. 

### Choose the Correct Filter Type 

Fiberglass filters are thin and inexpensive. Pleated filters usually catch more debris, while deep media filters need a matching cabinet. Washable filters must dry fully before reuse. Never wash a disposable filter or stack two filters together. 

### Check the MERV Rating 

MERV stands for Minimum Efficiency Reporting Value. Put simply, it measures how well a filter catches particles of different sizes. A higher rating can catch smaller particles but may restrict airflow in a system not designed for it. 

[The EPA suggests considering MERV 13](https://www.epa.gov/indoor-air-quality-iaq/what-merv-rating) or the highest rating your system can accommodate. The second half of that sentence matters as much as the first. Check the equipment manual before moving to a denser filter. If airflow falls or a return begins to whistle after the change, switch to an approved option and ask an [HVAC professional](https://wini.com/articles/hvac-inspection-what-to-know-win-home-inspection/) to review the setup. 

## Common Air Filter Replacement Mistakes 

Most mistakes happen because the job looks almost too simply. A quick pause before closing the cover catches nearly all of them. 

- Pointing the arrow away from the equipment 

- Forcing the wrong size into the track 

- Raising the MERV rating without checking the manual 

- Leaving the plastic wrapper on 

- Washing a disposable filter 

- Reinstalling a washable filter while damp 

- Missing a second system or filtered return 

- Ignoring water, rust, ice, or repeated odors 

## When to change air conditioner filter: Require an HVAC Professional? 

An accessible air filter is usually safe for a homeowner to replace. Diagnosing the HVAC equipment is different. If airflow remains weak after installing the correct filter, the system may have a dirty coil, blocked duct, fan problem, or electrical issue. Another filter change will not solve the underlying cause. 

Contact a qualified HVAC professional when: 

- Reaching the filter requires opening a sealed panel or working near wiring or moving parts.  

- The system short-cycles, freezes, makes unfamiliar sounds, or still has weak airflow.  

- You notice water, rust, scorching, repeated odors, or a new filter that becomes dirty unusually fast.  

A qualified HVAC professional can test the equipment and identify the cause. If you want a broader visual assessment of the home’s accessible systems, visit WIN Home Inspection to find a local inspector. 

## Conclusion: Change Your Air Filter with Less Guesswork 

Your first filter change may take fifteen minutes. Most of that time goes into finding the slot and reading the tiny print on the frame. The next change should be much quicker. Save the size, set up a reminder, and keep a spare if you have room for one. 

When the reminder comes up, look before replacing the filter automatically. Then remember the three things that matter: exact size, correct type, arrow toward the equipment. Close the cover. Turn the system back on. Listen for anything new. That's the whole job. 

## Frequently Asked Questions About Changing Air Filters 

### What happens if you never change your HVAC filter? 

The filter keeps collecting dust until air has trouble passing through it. Your system may run longer, rooms may feel uneven, and dirt can reach the blower or indoor coil. Energy use may rise as the equipment works harder. In severe cases, restricted airflow can contribute to icing, overheating, or an early system failure. The timing varies, but ignoring the filter eventually becomes more than a housekeeping issue. 

### Can I run my HVAC without a filter for one day? 

It is better to leave the system off until the correct filter is installed. Even during a short run, hair, dust, and other debris can move toward the blower and indoor coil. One day may not cause an immediate breakdown, but it adds avoidable dirt inside equipment that is harder to clean than a filter slot. Fit the replacement and close the cover before restarting the system. 

### Can I change the HVAC filter myself? 

In most homes, yes. If the filter sits in an open slot or behind an accessible return grille, you can usually replace it yourself. Match the printed size and follow the airflow arrow. Stop if access requires opening a sealed panel or brings you near wiring or moving parts. Once you know how to change air filter safely, future replacements usually take only a few minutes. 

### What are signs of a clogged AC filter? 

Start with the filter itself. A clogged one often looks dark, matted, or packed with dust and hair. Around the house, you may notice weaker airflow, longer cooling cycles, uneven room temperatures, or dust returning soon after cleaning. A whistling return can be another clue. These signs can have other causes, so check the filter first. If the problem remains after replacement, have the system inspected. 

How to Change an Air Filter in Your House: A Step-by-Step Guide

A guide to changing an HVAC air filter safely, choosing the correct replacement, following the airflow arrow, and knowing when to call a professional.

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