DIY Home Inspections for Air Quality and Mold

This is a method for doing quick home inspections, with a focus on indoor air quality, mold, and health. But this method isn't just about health. It's about how well-built and well-maintained a house has been from its roof to its plumbing.

It can be used when looking for homes to rent or buy, or even to assess the home you currently live in. It’s especially relevant to those with mold sensitivity or illness, multiple chemical sensitivity (MCS), etc. Honestly though, mold is bad for everyone, and can cause symptoms most of us don’t even associate with mold. See my video about mold illness for more information.

The first part of the inspection process involves screening listings online. Here are some tips for looking on websites for rentals or to buy.

1.) For rentals, be wary of homes that stay listed on the rental site for more than a couple weeks without being rented, especially in densely populated areas. Price history on Zillow will show this.

2.) Whether you’re looking to buy or rent, be wary of homes that were bought and sold frequently, more than a few times per decade. Check sale history on Redfin for this.

3.) The older a home is, the more of a chance it has historical water damage and mold. But newer homes can definitely have mold too.

Now I’ll tell you the features I look for in homes themselves when doing healthy home assessments.

You can see some of these features in the pictures on the listing, but many can only be discovered in person.

I start by looking at the exterior of the house. I’m mainly looking for signs that water could be leaking into the structure and causing mold to grow behind the walls, floors, and ceilings, which can affect the health of the occupants even if it’s not visible from inside of the home.

I start at the ground and then move upward.

1.) I make sure the ground isn’t sloping down towards the foundation, which can hold rainwater against and under the foundation.

Through capillary action, that water can wick up into the foundation, floor, and walls, and grow massive amounts of mold. This is called rising damp. Look at how it appears that moisture is diffusing up. This is a big red flag in a house. One way to prevent this is having the ground slope down from the foundation, 6 inches down measured from 10 feet away, ideally. Rising damp can also be caused by gutter and downspout problems, which I’ll discuss in a bit.

2.) For now, let’s move upwards and look at the foundation itself. There should be at least 6 inches of foundation exposed before the siding begins. Many, many homes don’t meet this criteria. It’s not a dealbreaker by itself, but a red flag to note. The foundation also shouldn’t have cracks.

3.) Moving upwards, let’s look at the siding. Are there any discolored areas? Look around windows and where roofs meet walls especially. This can be a sign that water is leaking into the home.

4.) Moving upwards, we can start to understand the potential causes of the stained siding. The first thing I ask: how deep are the overhangs? A study of 46 homes found that almost 90% of the exterior walls with no overhang had water damage. In contrast, only 25% of the walls with a 2 foot overhang had problems. The deeper the overhang, the less of a chance of water damage. Below is a house with no overhangs with the siding stripped off. Look at all that water damage!

5.) Moving upwards, let’s look at the gutters and downspouts, a crucial system that gets water down and away from a building. There should be gutters, first and foremost. They also shouldn’t have plants growing from them. The downspout extensions should extend at least 10 feet from the foundation. In most places I’ve seen, almost no homes have extensions that long, unfortunately.

6.) Moving upwards still, we look at the roof. Is it simple, or elaborate? Though elaborate roofs look nice, simple roofs perform much better. We often forget that the primary function of a house is to live in, not to look at. This goes for the rest of the house, too. Any unique architectural features like bay windows and skylights tend not to perform well. Are there funky building materials used? If a material isn’t widely used, there’s probably a reason why. When it comes to homes, simpler is better. We also just want to make sure the roof is in decent condition. It’s okay if there’s a little staining on it, but it shouldn’t be growing tons of moss and looking super old. That’s it for the basic exterior features.

Let’s now inspect the interior of the home for water damage.

7.) After walking inside, I try to notice my first reaction to being in the space. What do I smell? Is it musty? Filled with fragrance? Do I feel off? Your first reaction is arguably the most important thing to pay attention to.

Then, I primarily inspect places water flows to. Before I tell you which places I’m referring to, I need to tell you what to look for. The classic signs of water damage:

Staining:

Bubbling:

Cracking:

Peeling:

Rust:

And efflorescence, which usually presents as a whitish residue from water carrying salts to a material’s surface:

Where there are these signs, there is almost always mold, even if you can’t see it. Contrary to popular belief, a mold problem usually doesn’t appear as the classic black splotches you’d expect. It’s almost always hidden below a material’s surface that has those signs I mentioned. A leak is rarely just a leak, as mold can start growing within 24 hours. Think of how much can grow in a slow leak that has gone unnoticed for years. Another point: not all toxic mold is black. It can be many different colors.

Moving on, so where exactly do I look?

8.) The kitchen under the sink and around the bottom of the dishwasher.

9.) Then I check whether or not there is a kitchen exhaust system. These are incredibly important for removing the huge amount of pollutants generated by cooking. In some areas, they’re common, in others, they’re rare. Sometimes there’ll be an actual range hood, which works best, but sometimes there’ll just be a microwave that may or may not exhaust to the outside. If it’s not clear, check for a duct in the cabinets above the microwave.

10.) Then, I move to the bathroom. First, I look under the sink:

Around the base of the toilet:

The baseboard below the toilet supply valve:

And around the shower, especially the area of the threshold closest to the showerhead:

And where the wall meets the ceiling:

11.) Then I check to see that there is an exhaust fan, and that it turns on. If I have time, I also check that it sucks by putting a square of toilet paper up to it, and I check that it vents to the outside by turning it on and seeing if any vents on the siding flap open. There are a surprising amount of homes that vent to the attic instead of outside. Attic venting can be a huge problem in a house because moisture from showers can cause serious mold problems.

12.) Then I move to the washing machine check the ground under it and wall behind it for signs of water damage. I also smell the washer and dryer for a musty odor or excessive fragrances because they can be difficult to remove and can make your clothes smelly for a long time.

13.) Then I check the windows and external door frames for signs of water damage:

14.) Then ceilings:

15.) Then I check to see if the carpets are gross and high pile, which you don’t want, ideally. If you’re buying, you can remove them. If you’re renting, you obviously can’t.

16.) Then I check the HVAC system and hot water heater to see if they’re old, corroded, or leaking.

How do you know when to walk away from a home based on this inspection method?

I wish I could give you a concrete answer, but that can vary significantly based on the overall quality of homes in your location, your budget, timeline, how environmentally sensitive you are, etc. You’ll get a feel as you search for homes yourself. Though I tried to make this list of features as comprehensive as is feasible for quick inspections, it’s not exhaustive. There are other important health-relevant features, but I’ll leave those for another article.

Keep in mind that this inspection method cannot catch everything. One reason why is because landlords or inexperienced house flippers can mask water damage by repainting and remodeling, so it’s hidden instead of properly remediated. I’ve heard that called lipstick on a pig. Seeing the phrases “newly remodeled” “updated” or “freshly painted” in a listing isn’t necessarily a good thing. Another limitation of this method is that water damage can occur in spaces that aren’t visible, or in places we can’t feasibly go during a quick inspection like attics or crawlspaces.

If you want to see some actual walkthroughs of home inspections, you can watch my youtube video below, which contains all the information in this article and much more. The walkthroughs start at 11:24.

This video is about far more than just home health assessment. In it, we drive across the United States, and lots of interesting scenarios arise that allow me to answer some important questions like, “Is outdoor air really cleaner than indoor air?”, “Is opening windows a reliable way to bring outdoor air into a home?”, “How do different parts of the US compare in terms of buildings, types of air quality issues,” “How healthy are airbnb guest favorites to stay in?” and way more.

Anyway, I hope this method was helpful, and I hope you find your healthy home.