The majority of my mold inspections take place in San Francisco, where most of the neighborhoods were built many decades ago. Starting around the 1920’s, the tiled stall shower became very common in homes and apartments throughout San Francisco, and surprisingly, many of those showers still have their original tiled walls!
Bathrooms are often the first room that I visit on my inspections, both because this is where homeowners often see visible mold, and because this is where my meters often detect moisture problems. The shower depicted in the above photo is actually fairly common in terms of the problems it presents.
The tile is cracked and broken, the grout is missing in places, and mold is visible on both the cracks and the grout. These showers were all built with “custom shower pans,” meaning that the pans built on site, where mosaic tile was installed on a mortar substrate. Under the mortar it was common to “hot-mop” the area (essentially install a hot tar roof). After these shower pans were hot-mopped, both the walls and the pan then received a layer of mortar substrate. This mortar was typically floated over chicken-wire, which was stapled or nailed to some type of building paper.
These tiled showers have lasted for decades, but in almost all cases, the grout joints have failed and water has made its way past the tile and into the mortar substrate. At Bay Area Mold Pros, we use a variety of meters to detect this moisture, including thermal imagers. One of the problems within the mold inspection industry is interpreting just what this moisture means, in other words, we know we have moisture, but has this resulted in mold growth?
The best way to answer this question is through the use of air samples. Although some amount of surface mold is often visible on the grout joints of these old showers, it is oftentimes just that…surface mold. In other words, the moisture that has made its way past the tile may not (yet) be resulting in mold growth that is making its way into the air. That’s where air samples become so important.
Air samples provide a snapshot of the air that’s present in a particular place at a particular time. The cassettes used to collect these samples contain a lab slide. The mold spores attach to the slide, and the lab techs then place these slides under high powered microspores and analyze them. These techs will break out the mold spores present both by number (mold spores per cubic meter is the industry standard), and by mold type. Even though people within the industry often refer to the “species” of mold collected in air samples, the lab actually breaks the mold spores down to the “genus” level, which is more than adequate for the purposes of identifying the severity of a mold growth problem.
The bottom line…these showers need to go! After 50, 60, 70, or even 100 years, the shower has outlived its usefulness, and it’s time to replace it. Many homeowners opt to have seamless panels installed to replace the old tiles walls, thus avoiding the problems associated with grout.
For those who choose to have new tile installed, it’s crucial to have the grout “sealed” after installation, in order to address the issue of water making its way past the grout. Properly installed tile and grout will provide years of service for homeowners, thus avoiding the need to have Bay Area Mold Pros visit your home again.
In modern construction, concrete perimeter foundations are generally poured in such a way that the top of the foundation wall (where the “mudsill” is placed), is at least 8 to 10 inches above “grade.” This allows for an adequate amount of space from both any surrounding soil, and from any ground water. But in older construction, it was common to pour foundation walls that were level with the surrounding soil (on grade), and sometimes even lower than the surrounding soil.
This condition leads to both potential termite problems and water damage. When the mudsill (which is the horizontal framing atop the foundation that the ground floor studs are fastened to) comes into contact with the surrounding soil, it provides a clear path for termites to move from the soil into the framing. And any surrounding ground water can also be easily “wicked” into the mudsill, where it can then be transferred to the other framing.
Both of these conditions are potentially very problematic. The “quick fix” for this problem is to simply pull the soil away from the structure, crating as much distance from grade to the mudsill as possible. When this can’t be done, it is sometimes necessary to extend the foundation up to provide the necessary space between the framing and grade.
In the attached photo, the foundation vent is seen almost directly “on grade.” Foundation vents are commonly placed directly above the mud-sill, so it is fairly easy to determine the spacing between grade and framing by simply looking at how close these vents are to the surrounding soil. When these vents are placed as depicted in the photo, they are generally indicative of potential termite and water-intrusion problems.
Many older homes have a white powder visible on foundation walls and concrete slabs. This powder is actually salt, which makes its way to the surface of the concrete when it becomes saturated with water. This process, known as “efflorescence,” (which means to “flower out” in French) is strong evidence for the homeowners that they have water problems that they probably need to address.
In the below photo, the efflorescence appears along the lower 12″ of the perimeter foundation. This part of the foundation is completely “below grade,” meaning that the level of the soil on the outside of the foundation is higher than section of the foundation wall where the efflorescence is prominent.
In older homes, there was rarely any waterproofing applied to these foundation walls prior to the “back-filling” of the soil against the foundation wall. Additionally, there were rarely any drain lines (French drains) or gravel placed against the foundation prior to the back-filling. This lack of drainage, combined with a lack of waterproofing, often leads to the water intrusion issues that result in efflorescence.
This efflorescence itself is rarely a problem, but it signals to the homeowner that moisture is likely getting into the crawl space of the home. And this moisture often creates mold problems both within the crawl space, and in the living space directly above.
To deal with this moisture, homeowners are encouraged to speak with both drainage specialists in order to try to prevent the naturally occurring ground water from making its way into the crawl space, and also, vapor barrier specialists, who can install their barriers directly over the exposed soil (or concrete rat-proofing) of a crawl space. These barriers are very effective at reducing both the humidity and water vapor that are common in crawl spaces. And these measures go a long toward dealing with mold growth issues within the home.