Odor Coming Through Plywood Subfloor
A question about a different sort of ‘green’ building component, or rather ‘preventing’ the results of such.
Our condo is on the third floor of an old school, and all rooms have a concrete floor, except for one bedroom, which has a 1985 era plywood subfloor. The people who live below engage in fully legal substance use, and the odor continues to be awful in that room, and less so throughout our unit. Although we do not like, and consider the smell a health hazard (not passing any judgements of any sort), we are now used to it infiltrating the air in and around vehicle hvac systems, public sidewalks and other previously smoke-free atmospheres.
Years ago, I pulled up the carpet, removed nails, and replaced with screws to hold the plywood.
A solution might be to use some non-permeable tape along the seams of the plywood, but I need a tape recommendation.
Any and all suggestions welcome (moving is not an option)
Thanks
GBA Detail Library
A collection of one thousand construction details organized by climate and house part
Replies
I know there are some spot ERVs - one person posted recently about his positive experience with a window mounted unit. I imagine a slight positive pressure might be helpful if any units allow that.
Depending on your situation it might be a loosing battle to only approach the problem from the perspective of sealing the floor. As long as there are leaks in your (let alone their) ceiling, walls, vents etc. then the stack effect will bring air from the lower unit into yours and ultimately out of the building. It might be helpful to approach the problem from the top down.
Air filtering (read: carbon) might be a direction to go for reducing odors that do make it into your condo.
Lastly, you might have to talk to the people in question and see if there is anything that can be done. Failing that- any landlord etc. Ultimately it is something that would make it harder to sell your condo and - importantly- it effects your quality of life.
Thanks for the suggestions
I left out a few things:
All units are forced air electric heat pumps, so their duct runs below our subfloor and above their ceiling.
ERV not an option, and I don't want high end air filter running all the time, or ever.
If duct tape applied in 1986 is still sealing a duct, I'll have to get the brand, as the tape on our ducts deteriorated/lost adhesive years ago.
An easy solution would be to notify the landlord because we amended our bylaws in 2012 to make it smoke free, common areas and in units (grandfathered a few owners who are no longer here). I thought the tape could work, and it would avoid the uncomfortable face to face interaction.
It sounds like you may have somewhat answered your own question. If there are ducts running below the floor then likely that cavity has positive pressure. Between caulk and something like zip tape you might improve the situation by pulling up the floor, though there could be gaps/penetrations in places impossible to reach. If you are unable to vent and unwilling to filter then your options are limited and - at best- aiming to reduce rather than eliminate. The smell sounds pervasive and it seems like you have backing of bylaws so unfortunately the uncomfortable route probably needs to be taken if you want a resolution outside of moving.
I’m wondering if a floor leveling product would seal the smell out.
I had AeroBarrier done on my house, and when I was talking to the guy doing it he said that most of their business is either new construction, or multi-family dwellings where someone smokes cannabis. It's worth looking into. But I'd look into rolling up the carpet and sealing the subfloor first.
RE AeroBarrier - @ DC_Contrarian, was yours a finished house? What sort of prep/clean-up did you have to do to protect surfaces? I'm not sure if you've mentioned this on another thread somewhere.
We're moving again, and I'm interested in air-sealing well past the point of needing to also install mechanical ventilation.
Thanks for any thoughts,
The costs go up a lot on a finished house pretty much correlated to the labour involved in protecting / moving contents and installed fixtures.
100 year old remodel (go to 13:07 for their comments on a fully furnished house)
https://www.youtube.com/watch?v=CV5elSvasic
New construction:
https://www.youtube.com/watch?v=JYugiSwWoPk
Thanks for the links, and the pointer in the remodel video to their comments on furnished homes. That's a key consideration.
It was done during construction, after drywall and before painting, trim or finished floors.
I didn't think about AeroBarrier, which would be a good -if invasive and expensive- option to seal other sources of infiltration and reduce the stack effect. As far as tapes go- I've used zip tape on zip system plywood, but I cant vouch for it on regular old OSB. 475 dot com has some tape options, and I know Siga has some good stuff if you want a direction to research.
It's going to be quite hard to seal up all possible penetrations, particularly if there are wiring chases etc. making their way through the units. Based on the intensity of the odour, I also suspect a very, very low concentration in PPM would still be detectable on your side.
I'd throw out two solutions. One is an ERV setup for positive pressure which will only work with your windows closed..and you say this won't work for you. Two is carbon scrubbing.
I've been experimenting with carbon filters (as used in pot grow tents) to integrate to my HRV setup specifically to deal with wildfire and quite frequently, back yard fire pit smoke. I've got a few on hand, including a 4" AC infinity, and an 8" Terrabloom carbon filter. Coincidentally my daughter took an interest in keeping a chameleon which requires a pretty controlled habitat..and live crickets. Turns out the cricket habitat (to keep them live) truly stinks at times and was detectable in about half our house at the worst. An AC infinity 4" carbon filter and 4" AC EC fan completely resolved the situation, placed near the habitat. I was honestly taken aback by how effective that was.
In your position, I'd look at doing the same, perhaps trying a setup in that room...or consider approaching your neighbour to do this. If you do this on your side, VOC concentrations of many kinds will also be reduced in your space. It will also do some filtering at the PM10, PM2.5 levels in your space.
My recommendations if you go this way:
1. 8" Terrabloom carbon filter (129 US) which can stand on the floor and sits 2" high. It contains 15lb of activated charcoal.
https://www.amazon.com/TerraBloom-Activated-Filtration-Commercial-Applications/dp/B06X3VFK2T
2. AC Infinity 4" EC fan (99 US) https://www.amazon.com/AC-Infinity-CLOUDLINE-S4-Controller/dp/B07JB292JC/
The 4" AC infinity fan is much quieter than the 6" EC fan at low speeds, and will flow up to 205 CFM. On the 8" Terrabloom carbon filter, you're at around 100 CFM using the mid speed range.
That setup will flow plenty of air, will be very quiet on low to medium speeds, and can be placed behind a chair in a corner etc. to hide it. The fan can sit right on top pointing up, via 8" to 4" duct adaptors. It only uses about 20 watts at medium speed. You could refill the carbon canister or replace it, with a life of about 18 months.
Cheers,
Dennis.
Stuart,
The standard way to prevent odors from entering is to pressurize the room. You don't need a fancy filter or an ERV--just a simple fan that introduces a small amount of outdoor air into the room. If the room is slightly pressurized, the odors won't enter.
I like the KISS rule, so for sure try this. You may pressurise this room though and just make the smell issue worse elsewhere in your living space as you mention a sub floor with ducting under your condo, and above the concrete unit floor, correct? Either way, if there is air space and ducting in a void between you and the 2nd floor neighbour, then fully pressurising your condo may be the only way to do it.
A cheap easy way to test this is just place a cheap box fan in an open window blowing in sealed up with cardboard/duct tape. Try it in that room, and elsewhere in your space. If it works, then you have a direction to go. The minute that you open an window in your condo, then positive pressure will have zero effect. Carbon filtering will work regardless of pressure or windows etc. :-) It will also drop VOC and PM10/2.5 in your space.
I lived in an apartment above a heavy cannabis smoker back in university days so between that and noise transmission, it changed my attitude about living space separation, with respect to both acoustics and HVAC for the rest of my life. Living in that space was memorably unpleasant.
Stuart, what climate zone are you in? Stack effect will not be your friend on the 3rd floor with a cannabis smoker beneath as you get to the colder climate regions...
+1 for pressurizing the area you're trying to keep clear of smoke and odor. You need only a very slightly positive pressure, so nothing extreme. The only tricky part is that it is vital that you make sure that your air intake is bringing in fresh air. An activated carbon filter on that intake will also help. The downside is that it will have to be running ALL the time in order to maintain that slight positive pressure.
Regarding sealing up the subfloor, I would probably put down a layer of poly as a barrier, then a thin (as in 1/4 or 3/8" layer of plywood or OSB over it to prevent the finished floor from "slipping" on the poly. Secure the thin subfloor through the poly to the structural subfloor with screws. I don't think the wood subfloor alone, even if caulked, is going to stop the smell, although it will probably cut down on how much gets through.
I'd try the postitive pressure first though, since it's probably easiest to implement. What positive pressure does is to make sure all the leaks in your home leak OUT, not IN, so none of those leaks bring in any smells. As long as the fresh air you're bringing in to maintain the positive pressure is clean and smell free, you're fine.
Bill
I used tescon vana tape on the seams of an osb subfloor before installing carpet. The floor is over piers and leaked cold air pretty bad. It seems to be holding up one year on. At some point I'm planning to insulate and air seal from below but it going to be a big project
Thanks again for the suggestions, good information, and useful to solve future non-offensive odor intrusion issues. I'll go back to the huddle to determine what to do, but probably our bylaw amendment is the strongest and least expensive tool in the box.
stuartd,
I agree. I wouldn't spent too much time and effort trying to mitigate an activity that was not allowed in your building. Cannabis can be consumed in eaten form or in a vaporizer that emits no odor.
This is a good example of why spray-foaming the middle of a wall doesn't do much for airtightness--most leaks happen at penetrations, and gaps and cracks around the perimeter of an assembly. (Not that spray foam has anything to do with this situation, it just seemed illustrative.)