July 13



Mold behind bed headboard
Mold on wall, floor, and back of headboard.

Most of San Francisco’s neighborhoods were built in  the decades after the great earthquake and fire of 1906. The designs of these homes were surprisingly similar. Ground floors generally had a large unfinished basement space behind a garage, and all of the living space in the homes was generally located on the second story. San Francisco was essentially built out several decades ago, so homeowners started to look at these unfinished spaces as potential additional square footage for family rooms, additional bedrooms, and in-law units.

Many of these spaces were finished without permits, and the building methods employed were questionable at best. But even the spaces built out with permits still had to contend with a problem that is ubiquitous in San Francisco…ground water. The concrete slabs poured in these garage / basement areas were poured using the methods that were employed for decades, which was essentially to smooth out the soil and then pour the concrete. This resulted in a condition that allowed for a constant transfer of ground water from the soil into the slab itself. And this was exacerbated by the same transfer taking place from the soil into the perimeter foundation. This transfer of water results in (minimally) excessive humidity and condensation, and in worst case scenarios, a direct transfer or moisture into the flooring and walls of the finished space.

Bay Area Mold Pros was called out to inspect a small in-law unit in the basement of a 1940’s era home in the Excelsior District. The client had been living in this in-law unit and had developed some chronic health issues that he feared were related to mold growth. The photo at left depicts what I found when I pulled the bed away from an exterior bedroom wall. I found mold on the floating Pergo-like floors, mold on the wall drywall, mold on the drywall-wrap around the window, and mold on the drywall shelf used to conceal the perimeter foundation. In addition, the back of the bed’s headboard had what appeared to be mold growth as well.

The lab analysis of the air sample that I collected in this bedroom revealed high levels of not only Penicillium / Aspergillus mold spores, but high levels of the dreaded Stachybotrys genus of mold, commonly referred to in internet articles as “toxic black mold.” This entire apartment will require a professional mold remediation, as the problems present in this bedroom were also present in the adjoining closet and in the nearby bathroom.

Once the mold growth in this apartment is remediated, the building owners will surely want to ensure that it is rented out to either the original tenant, or a new tenant. In order to do this, it’s possible that by using dehumidifiers and air purifiers the excessive humidity and condensation can be controlled. The more expensive solutions, which involve actually trying to control the ground water through the use of French drains and sump pumps, would be the most effective, but they can also be cost-prohibitive. I always point out to clients that the use of French drains and sump pumps are an attempt to deal with the actual problem, which is ground water. On the other hand, the use of dehumidifiers and air purifiers are an attempt to deal with the symptoms of the problem, which are humidity and condensation.

We generally inspect several of these San Francisco basement units each week, and the earlier that we can identify potential mold issues, the better. If you suspect that you might have a mold growth issue in one of these apartments, give us a call at Bay Area Mold Pros. We only have two inspectors at Bay Area Mold Pros, Rick and and his son Tyson. Both Rick and Tyson are not just Certified Mold Inspectors, they are also Licensed General Contractors. Rick has been building and remodeling homes in the San Francisco area for 45 years, and Tyson has almost 20 years in the construction industry. This extensive experience allows us to quickly and accurately diagnose issues within your home which are conducive to mold growth. So if you suspect mold growth in your home, give us a call at Bay Area Mold Pros, we can generally be at your home within a day of receiving a call.


inspection, mold

You may also like

Mold Pros Standing Water

Mold Pros Standing Water
{"email":"Email address invalid","url":"Website address invalid","required":"Required field missing"}

Get in touch

0 of 350