[nhdanm]

This is an unusual situation. I live in an old mid-rise brick building with a flat black rubber roof which was replaced 4 years ago. Since it was replaced we've had a strong adhesive-like chemical odor in part of our unit (top floor) during the warmer months, especially on hot sunny days but not exclusively. Had the air tested and there are elevated VOC levels when the odor is present. We've gone through several rounds of trying to figure out the exact source of these fumes but without getting really invasive/destructive it'll be all but impossible to find it. So, we're going to try ventilating the roof just above our unit, in hopes of changing the air pressure so any nasty air goes out rather than in.

My question is: in order to be as sure as we can that this will be fixed, are we better off installing powered roof turbines, or passive ones? If powered, would the solar ones be effective? Do they still operate well enough passively on cloudy days?

I know there are other things to do - insulation, etc. - but for various reasons all other options have been decided against (too long to explain). Just want to find out whether we should spring for the powered vents, and how powerful if so?

Thanks!

 

[Nealtw]

This is an unusual situation. I live in an old mid-rise brick building with a flat black rubber roof which was replaced 4 years ago. Since it was replaced we've had a strong adhesive-like chemical odor in part of our unit (top floor) during the warmer months, especially on hot sunny days but not exclusively. Had the air tested and there are elevated VOC levels when the odor is present. We've gone through several rounds of trying to figure out the exact source of these fumes but without getting really invasive/destructive it'll be all but impossible to find it. So, we're going to try ventilating the roof just above our unit, in hopes of changing the air pressure so any nasty air goes out rather than in.

My question is: in order to be as sure as we can that this will be fixed, are we better off installing powered roof turbines, or passive ones? If powered, would the solar ones be effective? Do they still operate well enough passively on cloudy days?

I know there are other things to do - insulation, etc. - but for various reasons all other options have been decided against (too long to explain). Just want to find out whether we should spring for the powered vents, and how powerful if so?

Thanks!

You have no venting in the attic now. Passive is where I would start but you want more low intake than high exhaust, powered fans can cause other issues.

 

[nhdanm]

You have no venting in the attic now. Passive is where I would start but you want more low intake than high exhaust, powered fans can cause other issues.

Not sure I know what you mean by "more low intake than high exhaust" - could you explain a bit more, I'm pretty new to this -- to add a bit more detail, there's about a 16-inch cavity between our ceiling and the rooftop, with just fiberglass insulation. We suspect some material inside that cavity or the walls creates these vapors when it heats up, so the goal is to exhaust air from that cavity to the outside and make sure air from the cavity doesn't get into our unit.

 

[nhdanm]

Oh, also: for red-tape reasons, we REALLY want this to fix it. Trying something and then having to try again because we didn't do all we could have would be a giant pain.

 

[Nealtw]

Not sure I know what you mean by "more low intake than high exhaust" - could you explain a bit more, I'm pretty new to this -- to add a bit more detail, there's about a 16-inch cavity between our ceiling and the rooftop, with just fiberglass insulation. We suspect some material inside that cavity or the walls creates these vapors when it heats up, so the goal is to exhaust air from that cavity to the outside and make sure air from the cavity doesn't get into our unit.

It should have been built with low vents around the edges and well as the high vent thru the top.



You want the hot air to leave, it won't leave if it is not being replaced with cooler air.

 

[nhdanm]

It should have been built with low vents around the edges and well as the high vent thru the top.



You want the hot air to leave, it won't leave if it is not being replaced with cooler air.

Ok, that makes sense - but wouldn't a powered exhaust vent cause more air to be pulled through the space (especially on windless days) making it less likely that any would get into our unit from the cavity? I'm worried that unless there's a decent breeze, the passive vent won't be enough, and days without wind tend to be when the odor is strongest inside.

 

[Old Thomas]

You might be able to bake it out. Turn the heat up all the way, go away overnight, then open the windows and use fans to ventilate the place when you get home. Sometimes it works.

 

[Nealtw]

Ok, that makes sense - but wouldn't a powered exhaust vent cause more air to be pulled through the space (especially on windless days) making it less likely that any would get into our unit from the cavity? I'm worried that unless there's a decent breeze, the passive vent won't be enough, and days without wind tend to be when the odor is strongest inside.

It will also pull conditioned air out of your home.
You have radiating heat pushing air down now, all you need is to allow hot air to rise, no need for ore than that.

 

[nhdanm]

You might be able to bake it out. Turn the heat up all the way, go away overnight, then open the windows and use fans to ventilate the place when you get home. Sometimes it works.

Alas, it's been 4 years and several heat waves, and it's still there... also the building's heat system is steam radiators which are turned off for the season.

 

[carpdad]

You need intake vents and output vent is useless without the make up air. You probably need a carpenter to see if intake vents are possible somewhere. Roof can be cut and raised "duct" installed with a wind turbine or power vent to suck out the air. Or how about try laying down thin layer of gravel? May keep the rubber from baking. It could be tested with sheets of tyvek or such, held down with lots of bricks.

 

[Bud9051]

Natural air flow through a house is referred to as stack effect. In winter the warmer lighter air is pushed up and out upper leaks by heavier colder outside air pushing in lower leaks.

in summer this air flow can reverse if you are running air conditioning. Then the house is filled with heavier cooler air which pushes down and leaks out from the lower areas of the house creating a negative pressure near the ceiling which allows air from that smallish attic to be drawn in along with the chemical smell.

Creating natural ventilation in a small (short) attic is poor at best. Relying on temperature and wind also not reliable. A powered fan that operates on temperature OR can be controlled by you with a switch would be best, BUT it must have a supply of intake air and a lot of it.

Does your house have eaves where we usually find intake soffit vents? See Neal's picture.

Bud