I live in a two bed/2 bath with office condo in a high-rise building with glass curtain wall construction.   My neigbor smokes pot and it comes through my heat pump in the second bedroom.  This is because his heat pump and my heat pump are in the same wall as this is where the building riser is located so both heat pumps tie into the same riser.  

The builder tore out my drywall and fire caulked and insulated all the crack and crevices he could see and then reinstalled the drywall and repainted.   However, there is still some odor getting into the heat pump when I run it.  

My question:  rather than tearing out the walls again and trying to caulk and seal, would it be effective/reasonable to inject the space surrounding my heat pump with spray foam?  My heat pump is inserted into a "U"- shaped metal sleeve that goes from the floor to about a foot to a foot and a half short of the ceiling slab.  The sleeve is framed out by drwall on three sides (back, side, side).   There is about a 4" gap between the backside of the sleeve and the drywall and about 1" to 2" gap on each side of the sleeve between the drywall.  

I was thinking to fill the area around the sleeve would be less instrusive than tearing out the drywall again and would have a better chance of filling all the cracks, gaps and openings from the drywall seams (between floor and ceiling and at the studs).  

1) What are your thoughts
2) Should I be concerned with off-gassing?
3) Open or closed cell...sounds like closed cell is a better air barrier, but some of the gaps are large so I was thinking open cell. 

your help is greatly appreciated...thank you in advance.

Somebody must have some thoughts/experience on this topic, no? 

I think that plastic film and good weather sealing tape produce a more airtight seal than the foams that are stiff when cured.

You may also want to run a small ducted fan to the outdoors and use it to make sure that your area is always at a higher air pressure than his. This should prevent air/odor flow from him to you under normal conditions (ie, when your heat pump isn't pulling air in).

Posted By jonr on 23 Sep 2013 02:51 PM
I think that plastic film and good weather sealing tape produce a more airtight seal than the foams that are stiff when cured.

You may also want to run a small ducted fan to the outdoors and use it to make sure that your area is always at a higher air pressure than his. This should prevent air/odor flow from him to you under normal conditions (ie, when your heat pump isn't pulling air in).

I want to avoid opening the wall to get in there to seal with plastic and weather sealing tape.  So I thought about injecting the dry wall box that frames out the heat pump with foam as the least invasive way to stop the air passage.  

I don't have an odor when the heatpump off.  Only when it is turned on.  My neighbor and I share a common wall so that is where his air is getting into my air.  Anyway, I read that closed cell foam is an excellent air barrier and that foam generally doesn't shrink so I thought it would be a great solution.   I tried this forum to get an opinion from people experienced with spray foam and how it performs.

Posted By bbb77 on 23 Sep 2013 04:53 PM

Posted By jonr on 23 Sep 2013 02:51 PM
I think that plastic film and good weather sealing tape produce a more airtight seal than the foams that are stiff when cured.

You may also want to run a small ducted fan to the outdoors and use it to make sure that your area is always at a higher air pressure than his. This should prevent air/odor flow from him to you under normal conditions (ie, when your heat pump isn't pulling air in).

I want to avoid opening the wall to get in there to seal with plastic and weather sealing tape.  So I thought about injecting the dry wall box that frames out the heat pump with foam as the least invasive way to stop the air passage.  

I don't have an odor when the heatpump off.  Only when it is turned on.  My neighbor and I share a common wall so that is where his air is getting into my air.  Anyway, I read that closed cell foam is an excellent air barrier and that foam generally doesn't shrink so I thought it would be a great solution.   I tried this forum to get an opinion from people experienced with spray foam and how it performs.

I would like to see evidence of this. My experience with 2# foam has been just the opposite ,which is why I have 8" in my "hot roof" and 3.5" in the walls of my 1921 balloon frame. Further, we specify high density 2#foam nearly daily in our design/build HVAC business, as it is very often the only way to practically meet the new energy code in a 100-year-old house, while still meeting historical preservation mandates.

Posted By bbb77 on 18 Sep 2013 06:02 PM
I live in a two bed/2 bath with office condo in a high-rise building with glass curtain wall construction.   My neigbor smokes pot and it comes through my heat pump in the second bedroom.  This is because his heat pump and my heat pump are in the same wall as this is where the building riser is located so both heat pumps tie into the same riser.  

The builder tore out my drywall and fire caulked and insulated all the crack and crevices he could see and then reinstalled the drywall and repainted.   However, there is still some odor getting into the heat pump when I run it.  

My question:  rather than tearing out the walls again and trying to caulk and seal, would it be effective/reasonable to inject the space surrounding my heat pump with spray foam?  My heat pump is inserted into a "U"- shaped metal sleeve that goes from the floor to about a foot to a foot and a half short of the ceiling slab.  The sleeve is framed out by drwall on three sides (back, side, side).   There is about a 4" gap between the backside of the sleeve and the drywall and about 1" to 2" gap on each side of the sleeve between the drywall.  

I was thinking to fill the area around the sleeve would be less instrusive than tearing out the drywall again and would have a better chance of filling all the cracks, gaps and openings from the drywall seams (between floor and ceiling and at the studs).  

1) What are your thoughts
2) Should I be concerned with off-gassing?
3) Open or closed cell...sounds like closed cell is a better air barrier, but some of the gaps are large so I was thinking open cell. 

your help is greatly appreciated...thank you in advance.

The easy and cheap solution to end the problem is to call the cops

The easy and cheap solution to end the problem is to call the cops

Times are a-changing. That won't work in Seattle and Denver anymore.

Maybe I should ask this question differently and please forgive me I was thinking that the participants in this forum are familiar with spray foam performance and installation.  I apologize if I am in the wrong forum.   Question:

Is closed-cell spray foam an effective air barrier in your experience?

My experience has been usually, but not in the case of thin layers and gaps where the underlying materials expand or shift. For example, when the gap between two pieces of wood expands from 1/64 of an inch to 1/16th, the spray foam (or caulk) seal is broken. But tape continues to work.

Perhaps your situation doesn't have such gaps.