Most of our home inspections completed by Bay Area Mold Pros include an attempt to determine if moisture is present behind bathroom wall tile. Moisture often makes its way past wall tile, often through the space between the tile when grout is missing, or when the grout was improperly applied, or was never properly sealed. Homeowners are often surprised to learn that conventional grouts aren’t really waterproof, unless they have had a proper grout sealer applied, and re-applied when necessary.
Once water has made its way past the tile, it contacts whatever tile “substrate” was used. For decades, this substrate was made of mortar, and was “floated” onto the wall, generally onto chicken wire that had been nailed with spacers over some type of building paper. In the San Francisco Bay Area, this building paper was often the same “tar paper” used for roofing, and was also “asphalt-impregnated building paper” that was often used under exterior siding and stucco. These mortar substrates often lasted for decades, and indeed, many still survive throughout the area. Our family home in San Francisco, built in 1936, still has its original Art Deco bathroom wall tile in both the shower and above the bathtub. All of this tile was installed over a mortar substrate.
But mortar substrates require a certain skill level to apply them properly, and many modern tilers prefer to install tile over other simpler (and less costly) substrates, such as cement board and Hardi-board. When properly installed and waterproofed, these newer substrates will last for years, and although not as stable as mortar, they are very stable. But starting in the 1950’s, many builders started using standard drywall as a tile substrate, and over the ensuing years, these tile jobs have mostly failed. My wife and I purchased a home in the San Francisco Bay Area in 1980, and the shower tile was so “mushy” near the shower pan that you could move it by simply pushing on it with your finger. I gutted the bathroom and determined that the tile had been applied directly over 1/2″ drywall, which was completely saturated with water was falling apart.
I replaced the original 1/2″ drywall with a product that was fairly new in 1980, “green-rock.” This 1/2″ drywall was faced with green (rather than white) paper, and did not have the standard gypsum contents present in standard drywall. At the time, lumber yards and the newly introduced “big box” stores were selling this green rock as “waterproof drywall.” You can see where this story is headed, within a few years, this green rock had failed, and the shower needed to be gutted again. Several years went by and green rock was replaced by “purple rock,” which was again touted as waterproof drywall. But neither purple rock nor its predecessor, green rock, were ever meant as tile substrates, and should only be used as backing behind a properly installed tile substrate.
The wall tile depicted in the photo above was present in a home that I inspected last week in the San Francisco Bay Area. The lowest courses of the wall tile were loose, and when I pushed on one of the tiles, it simply fell off the wall, revealing what I suspected was behind it, standard drywall. Once water has made its way past the wall tile and comes into contact with the drywall, the drywall will suck up the water like a sponge, and will then fail. Mold loves paper, and because drywall has a paper face on both its front and back side, it makes a perfect host for mold growth. So when drywall tile substrates fail, it is very common for mold growth to occur.
So the lesson here is straightforward, never allow wall tile to be applied to any type of drywall in a water-setting, which includes shower enclosures and the walls above bathtubs. These installations require proper tile substrates and proper waterproofing. They also require appropriate sealing of the grout, and proper maintenance, which may include re-application of the grout sealer. And if the tile surface is properly maintained, it can last for many years. The tile in our family home is now 84 years old…and is still going strong!
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.
Even though winter now appears to be over in the San Francisco Bay Area, we received so much rain over the past six months that many homeowners experienced water-intrusion problems for the first time. Most of the homes in the greater Bay Area are built on perimeter concrete foundations and have “crawl spaces” under the first-floor framing. Until recently, no measures were taken by builders to prevent naturally occurring groundwater from making its way under any nearby homes (and into the crawl spaces of these homes).
Once groundwater has entered the crawl space, it is very difficult to dry it out. When water is present in building material (or soil), it will start to move from the wet area to the dry area. So the moisture under the home will attempt to move into the living space above, and the more water that is present, the more likely that this transfer of moisture will be successful. In homes with hardwood flooring, it is common to see the “cupping” of the hardwood slats, this is a clear indication of moisture that has made its way from the crawl space, past the hardwood flooring, and into the living space above. And once this happens, this moisture will almost certainly result in the growth of mold spores, and a call to Bay Area Mold Pros!
There are several things that homeowners can do when they have groundwater in the crawl space of their home:
Consult a drainage expert. There are many contractors in the San Francisco area who specialize in drainage issues and the installation of French drains. These systems divert water around and away from a home, and they are very effective at addressing this problem. Sump pumps installed in crawl spaces can also be very effective at controlling this excess moisture.
Vapor barriers. Once the “standing water” issues have been addressed in the crawl space (through either a French drain or sump pump), a vapor barrier can be placed over the soil or concrete in the crawl space, and this will essentially prevent the moisture within the soil from making its way into the home above. There are numerous companies in both San Francisco and San Mateo Counties who specialize in this work.
Run a dehumidifier. Homes that are experiencing the transmission of moisture from a wet crawl space into the living space above will have elevated humidity. One of the best ways to control this humidity is by running dehumidifier machines in the most problematic rooms of the home.
So the bottom line is this…if you have groundwater that has made its way into your crawl space, you need to address it, and if you don’t, you’ll be calling Bay Area Mold Pros to inspect your home for mold…because you will have mold!
I received an emergency phone call today from a client living in Los Altos. The client’s home is almost brand new, so I was a bit surprised when I arrived to find some workers ripping out drywall and insulation from the entryway ceiling.
The homeowners had discovered that a third story aluminum window had been improperly installed by the general contractor who built the home, so the contractor agreed to open up the exterior wall last week and to then re-install the window “flashing,” which is the material placed around the window flange to ensure a waterproof seal.
Unfortunately, once the exterior wall had been opened up, we received an unusual drenching of May rain that soaked the exterior of the home and made its way into the now open exterior wall. The homeowner phoned the contractor, who opted to not come out, because it was raining!
Within the next few hours, what started as a rather small problem, in one location, spread to the entire first floor of the house thanks to gravity.
Anyone who has ever suffered through a water leak within their home can tell you that where the water actually becomes visible is often quite far from where the leak originated. You can blame it on gravity. As soon as a water leak occurs, the water will start traveling downhill, and will always choose the easiest path on its downward journey. That’s why homeowners often say that water is leaking out of their recessed ceiling lights, these openings in the ceiling drywall are simply the easiest way for the water to escape.
The water is this Los Altos home travelled from the open exterior wall into the wall framing itself, and then travelled down the wall to the second story, and then travelled down the wall to the first story where it came into contact with a concrete slab. From there it travelled under the floating hardwood floors and then along the concrete slab, until it had travelled into every room on the ground floor of the home.
I measured the moisture content of all of the hardwood flooring, and it was all saturated with water. All of these floors will now need to be removed and discarded. Once hardwood floors have been saturated with water, they become cupped and unusable.
So the lesson here…if you have a leak…deal with it right now! Don’t wait until the rain stops (or any other excuse), because gravity is relentless. And the water that you think is contained to a small area will continue traveling until it reaches the end of its path. And the end of the path might just be your entire home.
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.
I’m still surprised when conducting my home inspections at how often I find examples of incorrectly installed flashing. “Flashing” is normally installed around window and door openings, and is made of a variety of material, but flashing is also required on many roof applications. Whenever a pitched section of roofing abuts a wall (or other vertical surface), flashing must be provided.
When installing roof shingles, the flashing is normally referred to as “step flashing,”and each course of roofing material has a piece of step flashing installed over the current course of roofing material and then against the adjacent wall. Step flashing is normally comprised of pieces of “L” sheet metal, but the key to a proper installation is to have the upper portion of the “L” flashing placed against the framing or sheathing of the abutting wall, and this is the important part…under the siding or stucco cover.
To save time and effort, some installers fail to remove the wall cover, and instead, place the L flashing against the wall cover. This defeats the purpose of the flashing, which is to prevent any rain water from getting behind the flashing and into the framing. The attached photos, taken at a 1930’s era home in the East Bay, depict how the flashing is actually placed on top of the stucco. This has resulted in gaps between the flashing and the stucco, and this is a direct pathway for rain water to enter the framing.
Directly below this roof section is a badly cracked and damaged section of stucco that is clearly water-damaged. And this damage is a direct result of the improper flashing. This home has mold growth problems related to a variety of issues, but one of the most obvious (and serious) issues concerns this roof flashing. And until this flashing is removed and re-installed correctly, this section of roof will continue to leak every time it rains!
The tenants living in this home in Oakland came home to a flooded basement. They notified their landlord, who sent a plumbing crew out within a day to shut off the water and to repair the broken supply line.
The landlord then had the water pumped out of the basement and brought in fans to dry out the space, assuring the tenants that this would, “…prevent a mold problem.” Well, the standing water dried out, but the tenants believed that they could smell mold and they decided to call out Bay Area Mold Pros for an inspection.
I immediately detected a very strong smell of mold growth, and I took several moisture readings with a variety of meters. I found that both the framing atop the foundation, and the drywall covering this framing, were saturated with water. I could see mold growing on both surfaces, and took air samples throughout the basement.
The lab found high levels of mold spores in every major category, including a fairly high level of marker spores, identified by the lab as Stachybotrys.
This case illustrates what can happen when an inadequate remediation occurs. Many homeowners believe that they can perform their own mold remediation by simply drying out an area that had been subjected to a water-intrusion event. But it’s not that simple. Effective remediations include not just a drying-out process, they involve an appropriate cleaning of all affected surfaces, as well as a proper cleaning of the air through the use of both air scrubbers and machines which utilize negative-air pressure to transfer the mold spores to a location outside of the home.
Property owners who try to save the costs of professional remediations are engaging in a “penny-wise and pound-foolish” approach to what can often be a serious problem. It’s much better to handle any potential mold growth problem as quickly and as effectively as possible as soon as the problem is discovered. Half-measures and money-saving schemes will likely results in what happened in this home…a science project!
I was called out to a 1930’s era home in San Francisco this week to perform a mold inspection of a large flat. I could see obvious signs of water damage around almost all of the windows, and when I started using my meters to determine if the plaster next to the windows was wet, the tenant told me, “Don’t worry, those are all new windows.”
As I moved from room to room in the flat, I could see that none of the original solid wood double-hung windows were still present, they had all been replaced by a combination of vinyl retrofit windows and solid wood retrofit windows. These retrofit windows were all installed in the original sold wood window frames, and although all of the new windows appeared to have been properly installed, the plaster adjacent to each of the windows was wet.
What many homeowners (and some contractors) don’t understand is this…when a new window is installed in an original wood window frame, the condition of the window frame itself will largely determine if rain water will eventually make its way into the home. And not just the window frame, but the surrounding wood trim as well. If the wood trim (typically a piece of 1 by 6 redwood on old San Francisco homes), fails, then rain water has a clear path to enter the wall framing. And if water makes its way into wall framing, you’ve got serious problems!
I took several air samples within this flat, and as expected, the mold spore counts were found to be elevated by my lab. There were additional issues within this unit, including water detected behind the tile above the bathtub, and elevated humidity in the basement below the unit. The real challenge for the client in this process is the fact that she is a tenant, and not a homeowner, so she must now rely on the property owner to “do the right thing” by starting to address the myriad construction issues discovered during the inspection.
I received a call from the long-term tenants in this old apartment on the peninsula about possible mold growth, and I saw numerous issues which are very likely producing mold growth. My meters detected moisture behind the original wall tile above the bathtub on all three walls, and also under the counter tile to the right of the kitchen sink (depicted in photo below).
The quarter-round tiles across the front of the sink are actually all missing, and the rusted edge of the original cast iron sink is visible. The substrate under this kitchen counter tile is most likely dimensional 1 by 8 lumber, which was commonly used in this era of construction. This substrate has probably been wet for numerous years, and mold spores are likely growing on this substrate.
The tenants told me that their landlord is not very responsive to their requests for repairs, and this is a common lament from my clients who rent their homes and apartments. One of the reasons to have a mold inspection completed in a rental unit is to establish a “paper trail” that can be shared with a landlord who is reluctant to make necessary repairs. If, upon receiving the mold inspection report the landlord is still not willing to have the mold-causing problems addressed, the tenants can utilize the report in any civil action they might pursue. Reports from independent third-party inspection companies can be very useful evidence in civil actions, and serve to bolster the tenant’s case.
Likewise, when scrupulous landlords are maintaining their rental properties, but have tenants who are complaining about issues (such as mold), a report from a certified mold inspection company that the mold spore counts within a rental unit are not “elevated,” this too can be a valuable piece of evidence in a civil case.
This past winter was the second wettest in two decades, and all of this rain resulted in myriad mold problems for Bay Area homeowners. Even though the calls for rain-related problems started “drying up” a couple of months ago, the problems created by all of this rain have persisted.
The owners of this home in San Mateo County noticed that their crawl space was flooded with water following a particularly heavy period of rain, and they contacted their contractor who then installed a sump pump system to deal with the standing water. Once this standing water was addressed, the homeowners thought that they were good to go, but the soil in the crawl space stayed damp for weeks, even though the sump pump was removing the standing water. This dampness can spike the humidity, and this elevated humidity can lead directly to mold spore growth.
The mold depicted in this photo is growing on the back side of a standard sheet of 1/2″ drywall. The stud bay had been filled with R13 batt insulation, but this didn’t prevent the growth of mold on the drywall itself. Once mold has grown into the paper on drywall (on either side), the drywall needs to be removed and discarded.
So this case is another reminder that moisture issues need to be addressed immediately following any water intrusion event, and this includes drying out the area with commercial dehumidifiers and fans. Mold spores will start to germinate within 24 to 48 hours of being exposed to water, so homeowners need to call in the professionals immediately upon discovery of any water issues. Any delays can (very likely will) lead to mold growth, so don’t wait, make that call!