Was asked to trouble shoot a mold issue in a Kneewall assembly.  When I arrived there was a damp and hot (+120) kneewall assembly that had no ventilation.  We corrected the mold issue by installing the proper ventilation to the assembly BUT now the client has a distinct smell that comes into the home.  Is there any way that anyone knows of to eliminate the smell?


As I have stated, mold has dried up, but is still there.  Ideas PLEASE

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Any mold remediation company would be happy to charge you big bucks to encapsulate the mold. If you are lucky, the smell is coming from the old mold. Before anything else, I'd spray everything with a 10% solution of clorox in water.

Sometimes the after odor cannot be stopped and is impossible to trace.

I would think again about applying any bleach solution to a mold issue. It can make the IAQ issue worse instead of better. I also beleive there may be a moisture issue in the kneewall space that is more than can be remediated by ventilation. Mold requires three items to survive; oxygen, water, and a cellulose based food source such as wood, drywall paper, etc. Remove one of these factors and it cannot survive. I would check for a moisture source to the attic space, bath exhaust, leak, etc. Just hot and under ventilated will not produce moisture. If the homeowner is noticing a smell, that indicates to me that you have communication between the living space and the attic, possibly allowing for condensation in the attic. Venting will increase the flow if there is communication to the living area. Zone testing will prove but will also draw the contaminated air into the house. Suggest a visual to find communication, air seal from living space, use of a microbial or non-chlorine mold or sporicide to kill existing mold (removal of the contaminated components is best but sometimes not within budget) and, if possible, use of low odor Kilz or similair product to seal any surviving spores to the surface.

A) look at waste plumbing stack if not vented to roof will make a lot of smells. B) let all bath exhaust out the roof or soffit C) water leaks roof or waste or water or steam heat system D)  do you see mold? If so take it out

Hi Tim.

Adding ventilation addresses the cause of the mold, maybe, but where the mold developed may be well beyond the kneewalls.

Where is this house located (approximately), and how many years has this mold issue been going on?  It is now a summer stack condition, so you may possible have air infiltration entering high, passing through the house, and exiting low.  That could be carrying the unwanted smell with it.

Is the house air conditioned?  Are there any air passages from basement to those kneewalls?  There are often 2 kneewalls, did both have moisture issues?  Plumbing vents often utilize kneewalls to pass up to the roof.  Check for air sealing.


I think to have mold, then there is moisture and is good if you can look at and make a thermographic survey of housing. It will serve as a preventive maintenance of the home and if there is a problem it will locate. At least with us in Bulgaria so doing. Look there's a lot of information on these issues energyaudit.bg.

I agree with Bud and Emilian, how do you know the mold problem has been corrected? Mold smells generally dissipate significantly when moisture is removed, and you should have noticed the difference scent-wise. You may be able to use a moisture meter if you can access the entire wall surface.

Try ground coffee when making an effort to get rid of a musty smell in a room. Although the smell of coffee will linger it will not remain, and it will eliminate the musty smell quickly and easily. mold south Florida

You may wish to try limeprime by earthpaint.net.



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