Originally Posted By: Caoimh?n P. Connell
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Hello AC Kelly ?
Last week construction guys finished the construction of a deck on my home. They installed floor joists that already contained mould. That is very common, and not normally a problem. I would suspect that if someone paid me for the study, we would find mould, to some degree
, on every floor joist installed in every house in the country (including floor joists that had just been ?bioremediated,? wiped clean and bleached).
Therefore, the question isn?t ?Is mould present?? but rather, the question becomes: ?Is moisture
present that could result in a proliferation of vegetative growth of mould.?
Every house has the capacity to ?soak up? and hold finite amounts of water before that water reaches a point where it is available for use by fungal entities; this is known as the ?hygric buffer? of the structure. By installing vapor barriers where one isn?t needed, and by covering concrete/block walls with sealant can decrease the hygric buffer, creating a moisture problem in a structure that was otherwise OK, and leading to a moisture problem leading to mould growth.
In your case, you stated that the crawlspace looked to be in pretty good shape prior to the installation of the VP and the spray foam ? and therefore, it probably was in good shape and didn?t need any adjustments. Why was the VP and foam installed, by whom and what was the rationale supporting their conclusion it was needed? Unless there were very specific reasons for installing the VP and the foam (other than myth), their installation may have sufficiently lowered the hygric buffer capacity and increased the moisture leading to the appearance of the new white material which may be mould (or the white material may have already been there... I haven?t got a clue.) However, in general, soils and concrete are great sinks for soaking up lots of extra water. Blocking those pathways means the water has nowhere to go (of course in some problem
houses, there is an unacceptable source of water flowing through the foundation walls, and soils which if landscaping does not correct needs to be addressed and sealing those surfaces sometimes is appropriate).
You say ?To throw in another twist, I found what I think is mold in one of my air ducts in the lower level of the house.? You have mould in ALL of the ducts in your house (just like all of the ducts in my house, your doctor's house, your kid's school and all other houses in the country). Indeed, you have mould on most surfaces in your home. Again the question isn?t ?It is there?? to which the answer will invariably be ?Yes,? but rather, what is it?s significance and is there a moisture intrusion problem that will permit the proliferation of the organisms. Take a look at my duct cleaning discussion at http://www.forensic-applications.com/moulds/ducts.html
for some additional information on ducts.
In general, without moisture a moisture problem (past or present), there is no mould problem. What is the foundation for your fears concerning moulds and did you get a chance to read my web discussions on health effects and indoor moulds?
Caoimh?n P. Connell
Forensic Industrial Hygienist
(The opinions expressed here are exclusively my personal opinions and do not necessarily reflect my professional opinion, opinion of my employer, agency, peers, or professional affiliates. The above post is for information only and does not reflect professional advice and is not intended to supercede the professional advice of others.)