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.
Many of my clients arrange an inspection with Bay Area Mold Pros, and then tell me that there was a leak, “…several weeks ago.” Mold spores are a part of our environment, and they are present in almost all of our homes. But these mold spores can’t grow until they are exposed to either water or excess humidity. Once exposed to water, mold spores can begin to germinate within 24 to 48 hours.
And there’s the problem for people who may be prone to procrastination. If there is a water intrusion event in your home (plumbing leak, roof leak, ground water leak), you must deal with it immediately! That’s why remediation companies usually have phone lines that are answered 24 / 7. Their crews will not only try to respond within hours, they will generally have their machines (fans, dehumidifiers, negative air pressure machines) set up and working within hours of arriving.
The photo below depicts the condition of the wall drywall in the basement of an old San Francisco apartment building. A plumbing leak occurred in one of the commercial street-level office spaces and the water made its way into the below-grade basement that became flooded. The water was allowed to evaporate, which took several days. But by the time the water had evaporated from the concrete slab, the wall drywall had been saturated for several days.
Mold spores are looking for organic matter to grow on, and they absolutely love the paper face of drywall. The air samples taken next to the drywall in the photo were found by the lab to contain not only the standard species, but a fair amount of the dreaded Stachybotrys, which is referred to in many internet articles as “toxic black mold.”
The lesson here…if you have a water intrusion…don’t wait! You need to dry out the area immediately, and you may need professional assistance. Don’t procrastinate, unless you don’t mind sharing your home with some moldy roommates!
If you own a home that was built in the 30’s or 40’s in San Francisco, or on the peninsula in San Mateo County, you may still have one of these tiled stall showers. They were generally placed adjacent to a separate cast iron bathtub in these old bathrooms. It is pretty amazing the number of these showers that are still in service, given the eras in which they were constructed.
My grandmother purchased a “brand new” home in the Mission Terrace neighborhood of San Francisco in 1936 for $5,000! That was a considerable amount of money in the depths of the depression, but she managed to pay it off early, and the home remains in our family to this day. The bathroom was finished in “art-deco” tile, and believe it or not, the shower is still being used every day, is still in pretty good shape, and it doesn’t leak!
But our shower is the exception to the rule. The shower depicted in the photo is in a 1940’s era home in San Mateo County, and it is no longer serviceable. During an inspection of this home by my company, Bay Area Mold Pros, my meters detected moisture behind the tile on all three walls, and under the tile in the shower pan. I took air samples both within the shower and in the hallway adjacent to the shower, and both samples came back with elevated mold spore counts.
If your home still has one of these original stall showers, it would probably be wise to have a mold inspector determine what you’re breathing when you’re using the shower. There is really no way to “repair” these old showers, they’re simply too far gone. Most of the pans have failed (they used either a “hot-mop” waterproofing, or a sheet metal pan in this era of construction).
If you determine that your shower is still serviceable, remember to keep it clean, and you may wish to apply some grout sealer. The grout on these old showers is often missing in places, but you can prolong its life with frequent applications of a modern grout sealer.
In modern construction, you’ll always see a space from grade level to framing. This space varies, but it will minimally be about 8″ at the low point. This space helps to address two problems: pests such as termites, and ground water; both of which are trying to enter your home. In older construction, it is common to find the mud-sill at the same (or sometimes even lower) elevation as grade. This is a potentially serious problem, as both termites and water have direct contact with the framing.
When I first looked at the exterior wall depicted in the above photo, I thought it looked pretty sound. The stucco ended at a weep screed, and there was about 8″ spacing between the weep screed (which represent the bottom of the framing / sheathing) and grade. But then I realized that the foundation vents were within the foundation wall, which is unusual. Foundation vents are normally placed atop the mudsill (or higher), but they are almost always placed in the framed portion of the flooring or cripple wall above the foundation.
As I looked more closely, I saw that what I thought was the concrete foundation was actually several long pieces of galvanized sheet metal. So the builder who had performed the last remodel of this home had stripped the old stucco off, sheathed the framing with 1/2″ CDX plywood, and ran the plywood down to the original mudsill, which was at grade.
This resulted in plywood (and the floor framing behind the plywood) extending to grade. So the builder decided to cover the lowest section of the framing with sheet metal, hoping this would provide a “break” between grade level and the stucco and weep screed. Only time will tell if this decision will accomplish what it’s intended to accomplish. In any case, it’s probably preferable what existed previously, which was likely direct contact between the framing and the adjacent soil.
In 1977 I purchased my first home in San Francisco, a Queen Anne Victorian built one year after the 1906 earthquake and fire had devastated San Francisco. The front stairs for the home were original, and extended from a raised concrete landing to a small enclosed front porch just outside the original front door. Everything on the stairs above the concrete landing was solid wood…the stair stringers, the treads and the risers. And even though they were seventy years old the year I bought the home, they were actually in pretty good shape!
But as the Victorian era was ending in San Francisco, so was the era of building homes with exposed wooden front stairs. Terrazzo stairs became quite common, with both the treads and risers for these stairs being fabricated off-site, and then placed over wood framing or a concrete support. And although the Terrazzo material was solid and not prone to water intrusion, the joints where the treads and risers abutted the vertical framing often leaked after decades of service, with the water generally making its way into the basements of these old homes.
Although less common than Terrazzo, many old homes in San Francisco were built with brick front stair systems. These systems almost always involved a brick cover over a wood-framed or concrete substructure, and just like the Terrazzo stairs, once the bricks start leaking, the sub-structure becomes saturated with water.
The good news was that these systems which were wood-framed were almost always left as open framing, so the framing was allowed to dry out between rain storms. And if the supporting structure was solid concrete, there was no wood framing present to rot, even if the water intrusion was significant. But over the years, as real estate values continued to rise at extraordinary rates, the owners of these old homes in San Francisco started to add living space to these old basements and garages, and the space under these old entry stairs often became closets.
Once the framing under these stair systems was covered with plaster or drywall…the problems began. Because now the water intrusion events resulted in not only the soaking of the supportive framing, but the soaking of the plaster or drywall covers as well. And this of course eventually led to…mold growth.
I had an inspection this week at a 1950’s era home in San Francisco’s Noe Valley, and the front stairs were finished with a brick cover. Once the wood framing under brick stairs gets saturated with water, it’s going to support mold growth, and that’s exactly what happened in this home.
If your front stairs have developed leaks, several things will need to be done to address the problem. First, the leak(s) must be stopped! Until the stairs are properly waterproofed and the leaks have been stopped, there is no point in doing any repair or remediation work, but once the leaks have been halted, it’s time for the next steps.
If the leaks have been occurring for a long time, it’s very possible that any wood framing present has suffered rot, and any rotted framing will need to be removed and replaced. The demolition work should be done by a certified mold remediation company, and once the demo work has been completed, then a thorough cleaning of the surrounding area also needs to be completed. Once the demolition and remediation work has taken place, it’s time to have a licensed general contractor take over and complete the framing (and other) repairs.
As you can see, these stair problems can be a headache and can be very costly. But you ignore these stair leaks at your peril! Because the problem that exists today will only get worse if it’s subjected to additional rain and water intrusions.
In 1936, during the depths of the Great Depression, my grandmother received a small inheritance after a relative had passed away, and she bought a brand new home in the Mission Terrace neighborhood of San Francisco. The purchase price was $5,000, and the home has remained in our family for the ensuing 84 years. Like almost all homes built in San Francisco during the first half of the twentieth century, the entire ground floor of the home was an unfinished basement / garage. We recently decided to do some work in this large unfinished space, and I had to add a small “footing” in order to move one of the original structural posts.
I removed a section of the original concrete slab, about 10 square feet of surface area, and then excavated the soil beneath the slab in order to place some structural steel there for the new footing. While performing the excavation, I was a bit surprised at how wet the soil was beneath the concrete slab. This home, like most San Francisco homes, is a “zero property clearance home,” meaning that it abuts the homes on either side of it. This might lead some to believe that there was no way for groundwater to make its way under this home, but there it was, just a few inches below the slab. It is likely that this ground has been damp for the entire time that this home has been here…all 84 years since its construction!
Now that I spend much more time looking for mold than I do building homes, I find that most of the homes that I inspect around the San Francisco Bay Area have groundwater issues, and this groundwater can lead to both elevated humidity, and the direct transfer of water into the living space above concrete slabs and crawl spaces. And this water and humidity often result in mold growth.
During my mold inspections of homes that are located throughout the San Francisco Bay Area, I use a variety of moisture meters and humidity sensors in an effort to locate water. In crawl spaces and garages, the most obvious indication of ground water issues is the white powder that appears on concrete that has been saturated with water, which is called efflorescence. This white powder is the residue of the salt and minerals that are left on the surface of the concrete after it has dried out. It isn’t often that I get to see an actual excavation in one of these old city homes, as I recently did in our old family home, but if I did, it’s very likely that I would find water-saturated soil, a problem for homes found all across the San Francisco Bay Area!