Mold in crawlspace

I found this mold in the crawlspace of a recent inspection. It is very common to find some type of growth in crawlspace in this area and usually recommend better ventilation, gutters, and grading improvement. But I noticed this mold was begining to damage the floor joist. Would you recommend remediation in this case. There was no signs of mold on the interior and no testing or sampling was done.







I would certainly refer that to a specialist. Depending on the moisture content in the wood I say something like this:

“There is a (high/moderate) moisture content in the wood structures inside the crawl space (xx% moisture was measured in some areas). Wood will decay at moisture levels > 28% and will support fungi growth at levels in the low-20s. Moderate to heavy fungi was observed in many areas of the floor joists. Because of the issues with high moisture content in the wood structures that result in fungi growth, it is recommended that a qualified individual: 1) remediate (kill) the fungi growing in the crawl space, 2) take appropriate measures to eliminate the environment conducive to future fungi growth, 3) eliminate the environment that will cause the wood to decay. The services of a mold remediation specialist and/or a crawl space specialist should be considered to achieve the desired results. Options to reduce the moisture levels include, but are not limited to, elimination of water intrusion into the crawl space, increasing ventilation, installation of a vapor barrier, increasing the size of the vapor barrier, or installation of a humidistat controlled fan. Here’s useful information from the EPA about fungi:

Most definitely remediation is required. Control the moisture & RH% first then dry ice blast followed with an application of fungal paint. Doug

Hello Mr. Blair –

It’s difficult to determine from just a few photos, but the white discoloration appears to be similar to the organism responsible for “dry-rot” known as Serpula lacrymans. This organism can seriously degrade the structural integrity of the wooden structures.

The relative humidity, etc, is not an issue with Serpula lacrymans since this organism literally brings its own water with it (it transports water to a food source via long tendrils) thereby rotting even dry wood; thus the name. So you will need to find the “root” and sever the lowest point of the “tree.” The organism will then die. However, I would also recommend a structural engineer to test the structural integrity of the wood, since I have seen floors fail (collapse) with this organism.

So to the extent that is it with Serpula lacrymans, I agree with Mssrs. Funderburk and Plummer in that is should be remediated, and quickly at that. To help you with further mould and fungi related issues, I have put up a new web site with tons and tons of photos (some of which include the rots). The new page is located at:

Caoimhín 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.)



As always, a great post and great information.

Yes, thank you!