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Is the air in a semi-detached house shared between the two units?

BRENDA Koehlert | Posted in General Questions on

For three years I have been trying to keep the neighbor’s smoke and chemicals from leaking into my house. Some builders told me there was probably no way to do it. Others told me there was a cinder block wall from the basement through the attic between the two units, so no air should be coming through at all. These two answers conflicted with each other and made my problem seem even more of a mystery.

Finally I gave up and put my house on the market. I had to have an inspection done as part of the realtor process and the inspector left the door open to the attic crawlspace. I had never gone up there at all, ever. I went up to shut the door and then I saw that the cinder-block wall between the houses for the first time. It had lost the cement between the blocks and I could see through it into the attic next door. This is why so many smells and smoke come into my house–the wall is full of chinks.

Since the kitchen cabinets are up against this wall and the problem is most noticeable in the kitchen I was thinking I could take the cabinets down and reseal the wall. I got an estimate of $2000 to do this. But my question is this—would this be guaranteed to fix the problem?

Everywhere else in the house the only places that are open between the units are the baseboards which I could caulk. But I’m unfamiliar with this whole situation. If the cinder block wall leaks everywhere, could the neighbor’s air still travel around somehow and get into my house. I have already started the selling process on my house. I would have to turn it all around and put myself in more debt to do this. Is it a fool’s errand to save a place I love? I have already spent so much money trying to fix this.

Thank you for your insight,
Brenda Koehler

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  1. Jon R | | #1

    Air sealing between units helps but you need to make your air pressure higher than your neighbor's. You could use a fan to do this inexpensively on a makeshift basis and see if you like the results. Also check for anything else that exchanges air (like HVAC).

  2. GBA Editor
    Martin Holladay | | #2

    I agree with Jon. You need to pressurize your house with respect to the outdoors. Ideally, the result will be that your apartment will be pressurized with respect to your neighbor's apartment.

    This can be accomplished with a central-fan-integrated supply ventilation system (assuming that your house has a forced-air heating or cooling system -- that is, a furnace and ducts or a heat pump and ducts). Or you could simply have a supply fan installed in a wall to pressurize your apartment.

    This approach comes with an energy penalty, but eliminating the odors may be worth the small increase in energy costs. It's probably worth a try.

  3. Steve Knapp CZ 3A Georgia | | #3

    Brenda. You could pressurize and ventilate your home without introducing excessive levels of moisture by using a ventilator dehumidifier with a HEPA filter. (I think this is what Martin was suggesting.) Ultra Aire and Broan are a couple of manufacturers. A side benefit of this approach is that you will enjoy much better indoor air quality.

  4. GBA Editor
    Martin Holladay | | #4

    While Steve is worried that ventilation will introduce lots of exterior moisture, we have no idea if that would be a problem. If you lived in Florida, it might. If you live in Vermont, it wouldn't be.

  5. BRENDA Koehlert | | #5

    Thank you Jon, Steve, and Martin for your responses. I greatly appreciate your knowledge and your help.

    Brenda Koehler

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