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!
I often receive calls from tenants regarding their concerns about mold within their homes or apartments, even though their landlord has assured them that “…there’s nothing to worry about.” The photo below depicts the siding that was removed from a a San Francisco town home after it was discovered that a plumbing supply line was leaking inside this wall.
The landlord sent out his “mold expert,” who took an air sample in the room affected by this plumbing leak (kitchen), and the expert assured the tenants that there was nothing to be concerned about (even though he hadn’t yet had the air sample analyzed by a lab!)
I started using my moisture meters in an effort to determine the extent of the water intrusion, and I found that the drywall on the inside of the wall depicted in the photo was saturated with water. When I tested the base cabinet, which was a “Lazy Susan” base, the back of the cabinet was also saturated, and I could smell mold within the cabinet. I then tested the wall cabinet, and it too was saturated. I took an air sample within the base cabinet, and the lab determined that the mold spore count was elevated (about four times the number of mold spores as the control sample).
The landlord had already told the tenants that his solution to this issue was going to be to run a dehumidifier within the kitchen, but I explained to the tenants that this mold problem had already moved beyond the stage where the problem could be addressed with a dehumidifier, and that both the cabinets and the drywall would need to be removed, and that a full mold remediation (by a certified professional) was needed for their home.
Many of the landlords and property management companies that I deal with are professional and responsible, and want to take whatever steps are necessary to deal with mold problems correctly. But many of the landlords that I deal with decide on a “…penny-wise and pound-foolish…” approach to these problems, and this is when tenants are wise to bring in their own independent mold inspection company.
I always explain to my clients that as an independent mold inspection and testing company, I have “…no dog in this race.” I do not perform any remediation work, so there is no reason for my reports to exaggerate the extent of any mold problem. When the tenants in this case presented their landlord with the report from Bay Area Mold Pros, he agreed to do the right thing and to proceed with a professional remediation.
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.