How to Deal with Smelly Houses

Ahhh. The Smell of Money. To real estate investors, that smell is usually pet urine, decay, mold, smoke or some other strong odor that makes most retail buyers run for the hills. Now that you own the aromatic abode, how do you sink the stink? We are going to cover the 2 most common sources of bad smells and what to do about them, but first a word from our sponsor. Just kidding – I wish. But seriously, go buy one of these:

Ozone Generator


Every serious real estate investor needs at least one ozone generator machine. These things work great at drastically reducing the amount of even the strongest odors like smoke and herds of animals in the house. I buy the exact one shown above off of Amazon for about $90 (it is closer to $60 during non-pandemic times). If you get one, make sure to get one with a “Hold” setting so that you can keep it running overnight at vacant properties. They come in all different sizes and price points, but they pack a punch, so you may not need as large as you think. And don’t run it while you are in the house, genius.

Also, unless you are into buying ozone machines about every other month like me, include “Pick up ozone machine” on your honey-do list before you sell the house. I am probably on machine #10 because I always forget to grab them when the rehab is done and the house is pending sale.

*Disclaimer: I am not a healthcare professional, so please do your own research on what is safe for you to use based on your health situation and desire to live dangerously.

Cat Pee

Demon Spawn

The Mother of All Odors. Cat urine is one of the worst, strongest smells on this earth. There is a reason that smelling salts are made of similar molecular compounds as cat pee. Is there a cat currently sitting there peeing on your floor? No? Then, your first step is to locate the source(s) of the smell. It could be in the carpet, the pad and even the subfloor if it got really saturated. Don’t forget about kitchen cabinets!

Cats also like to spray walls, so check out the drywall about 2 feet up from the floor. Turn the lights off, take a black light and shine it on the floors and walls to see what you are dealing with.

Warning: You cannot unsee this once you have done it. You have been warned.

For areas that have a small amount, douse it liberally with urine enzyme remover and wipe down/soak up as much as you possibly can. Let it dry out, and do it a few times to be thorough. There are several popular brands of enzyme removers, so choose one with good reviews and follow the directions on the product.

If you have ever bought a house like The Cat House, you will want to grab a dumpster or five, because you are going to be chucking some carpet, drywall and subfloor. In cases of serious mental illness, disability or pet neglect, owners just let their pets go in the house repeatedly and never clean it up. Cats in particular like to go in the same place, which means that it can soak all the way through the carpet and pad and into the subfloor. Yay.

When in doubt, throw it out. Home buyers and tenants can be REALLY sensitive to smells. And let’s face it, as investors who look at a lot of stinky places, we tend to get desensitized in the olfactory zone compared to normal people. You don’t have to replace the entire subfloor or drywall all the way up, just the saturated sections. You can seal the rest with a heavy coat of primer.

Have I mentioned ozone? You should be running that bad boy pretty much the whole time you are not physically in the house. I would buy stock in ozone companies if I had any money left over from buying cat pee houses.

Once you have tossed out the worst of the stank, sealed in the rest and put the pretty new carpet in, you should now have a house smelling like a field of daisies that an FHA buyer will write an offer over asking price on.


Eu de Marlboro

Let’s start with the obvious – air that sucker out. Open a lot of windows and get some good airflow running through the place.

For professional smoker homes, you have to get the nicotine residue off of the walls, trim and ceiling before you even think about painting. One tried and true way to scour walls and woodwork is using TSP (Trisodium Phoshate). This stuff is powerful, make sure you read up on how to best use it.

Your next investment is a high quality oil-based primer. DO NOT skimp on this part. Paint is porous, so you can’t just paint over smoke saturated walls and call it good. It will smell fine for a couple of days, then come back with a vengeance once the smell bleeds through. Kilz, B-I-N and Zinsser all make good odor blocking primers that can seal in strong smells. Oil based = strong fumes. Plan accordingly with proper ventilation and PPE.

For surfaces that cannot be painted (carpets, curtains, etc.), it is normally best to ditch the affected materials and start over if enzyme and ozone is not working.

You will also want to vacuum out your air ducts, and don’t forget to give your furnace’s A-Coil (evaporator coil) a really good cleaning as well, as it can be a hidden pocket of odor (and hair).

While you are going through all of these steps, you will want to run your ozone generator after you finish up work for the day on the house.

Now that you have cleared the air, move on to your HGTV design and try to forget that all of this smelly business even happened.

P.S. – See below for a noteworthy unpaid product placement


BioSafe makes a pretty cool technology which uses a cold fogging technique that releases a mist which kills airborne contamination and microorganisms. It is non-toxic and environmentally safe. I have not yet used the product myself, but I know several investors who have used it and swear by it. At the time of this blog post, I have heard that prices are around $.10 per sft in the Omaha area. I plan on trying it out soon – it sounds like witchcraft to me.