On 3/6/2012 9:05 PM, Duesenberg wrote:
Hee are some ideas:

Shared dryer vents?

No

Shared Stove top cooking vents?

No

Shared plumbing stack venting? unlikely but if there is one missing
missing trap on one sink somewhere and the plumbing venting is shared
then air may be able to travel...

Hmmm--not sure about this. I'm thinking I would have seen this when the
walls were open. Might have to ask the plumber about this

Chimney sharing?

No.

Light fixtures on the ceiling? check for air leaks, it's a stretch but
worth a try.

I rather doubt it, but--other than seeing smoke coming out, it sounds
like major demolition to determine it.

Somebody mentioned electrical outlets

Interestingly, we have some metering for several of the houses on our
block with our utilities, in a locked box that Con Ed has access to.
However, I generally don't smell cigarette smoke in there, so it seems
unlikely.


how about attic access doors??? silicone seal the cracks in the attic
door access to stop airflow and if you ever need access back into the
attic, it's easy to cut and reapply new sealant

There is no attic. However, there is a dead space between the top floor
ceiling and roof. I suppose it's possible, but also sounds like a major
job to determine--and in any case the problem is primarily downstairs on
the living floor.

Something between the garages?

No, the garages are not adjoining.

Central vaccuum venting? or collection tank?

No central vaccuum

Air moving between the floor joists?

This sounds possible, for sure. Again, it sounds like a big job--hope
I'm not driven to this level of desperation. But while we only dug up
the concrete floor on the basement level (for plumbing), it still would
have been easier to check during the demolition. The renovations were
pretty extensive, but it was by no means a gut renovation.
Thanks for all the suggestions--I'll certainly keep them in mind. Will
pursue them if I feel we have to, but we're rather tapped out
financially by now.

Steve



--
Mark & Steven Bornfeld DDS
http://www.dentaltwins.com
Brooklyn, NY
718-258-5001