Renovation & Design
Renovation & Design
Efflorescence on a basement floor due to moisture
Question: I am experiencing a white powder coming up through the basement tiles in my 40-year-old Charleswood home. Can you recommend a cure? Possibly, a sealer that I can purchase and apply myself.
Thanks, Gary D.
Answer: The cure to efflorescence on a basement floor is to find the source of moisture causing it and eliminate it. That may require evaluation of your exterior grading and water management, sump pumps, plumbing supply, fixtures, drains and any other mechanical systems that may potentially leak.
Yours is a very common question that I receive; what is the white powder I see in my basement and how do I get rid of it? As described several times in previous columns, the white powder is known as efflorescence and is simply minerals that leach out from concrete in the form of a salty powder. This typically occurs after the concrete becomes wet and then dries, or from water sitting on many types of masonry products. The water will draw the minerals to the surface of the cement-based materials and leave behind the white, powdery residue when it evaporates. It is essentially harmless, but does provide good evidence that excessive moisture is present, or has been, in the building material it is found on.
There is no way to seal, paint, or waterproof your basement floor to prevent this from occurring, unless the water is coming from a source inside the home and leaking onto the floor. In that instance, the efflorescence should not be your concern, but the item that is actively leaking. In your case, there may have been some mechanical or plumbing component that has been dripping onto the floor. That moisture may have seeped through the gaps between your floor tiles, wet the concrete floor slab below, and caused the salts to rise up beneath the tiles. Once the amount of efflorescence becomes large enough, it will push its way up through the same gaps the water leaking into. Then, the tiles will likely come loose and replacement or securing them is likely.
The first place to look for water leakage may be your plumbing system. Go through the basement and look for any slow dripping plumbing pipes. This could be your supply pipes, likely copper in a house your age, and may also be due to condensation on the pipes. That may occur on cold water supply piping that is too close to a heat source, during humid summer weather, or on hot water supply pipes that may be too close to a source of cold air.
If that is suspected, simply installing inexpensive foam insulation pipe wraps around the offending sections may stop the problem, completely.
That also commonly occurs on the refrigerant lines that enter the furnace plenum from the air conditioner condenser. If they are not well sealed at the junction, or have deteriorated insulation, they will sweat and drip. Either cause may be eliminated by proper insulation and sealing, using easy to install foam pipe wraps and aluminum tape, or other sealants.
While air conditioner pipes may sweat, other items in that system, and high-efficiency furnaces, frequently leak in basements due to their condensate systems. Both the heating and cooling systems will produce large amounts of water during their regular cycles. This water has to be properly drained to a floor drain, condensate pump, plumbing drain, or sump to prevent it from winding up on the basement floor.
This can be inspected by watching the condensate drains while those two systems are operating. If you see water draining properly through the clear, plastic tubing attached, that should be a positive sign. Once the water leaves that hose, it should be immediately directed into a condensate pump beside the furnace, or other proper drain. If there is water on the basement floor in that location, or wet concrete, then something is leaking. Replacing the plastic tubing if it is clogged, cleaning the pump, or securing the end of the hose inside the floor drain may be required to stop the leaking. If it is severe enough, the water may flow to the area under your floor tiles, leading to the issues already discussed.
In addition to the heating system, water heaters and washers are notorious basement components that frequently leak. Water heaters may slowly leak when their TPR valves are damaged or are physically contacted. Storage right beside the tank may cause an inadvertent compressing of the valve release lever. If excessive rust stains are seen near the bottom of the tank, or small drops of water on the floor, call a plumber for immediate replacement, before a larger breach occurs.
For washers, leakage may be caused by loose or damaged hoses at the supply valves, a poorly secured drain hose, one improperly draining into the floor drain, or an amateurishly installed plumbing drain. Older washers may also leak from the inside, which will require a swift replacement with a newer model.
The dryer should also not be neglected in your evaluation, as a poor quality or improperly connected dryer vent can also be a source of significant water vapour. If you have a flexible plastic or aluminum vent, it is easily damaged and may allow warm, humid air from the dryer to leak into the basement. If that air hits a cold window, water pipe, concrete wall, or basement floor, condensation is almost a certainty. Replacing the vent with a solid metal, duct-taped pipe will prevent blockage, damage, and also help your clothes dry quicker.
The final piece of the puzzle may be moisture leaking into your basement through the foundation walls, or from wet soil under the floor slab. Ensuring you have good grading around the house and ensuring rain and snow runoff are directed well away from the foundation walls will help prevent those two things from occurring.
Stopping white, powdery efflorescence from bleeding up from beneath your basement floor tiles will require investigation as to the moisture source behind it. Ensuring none of the plumbing or mechanical systems in your home are leaking, and that water is not seeping into the foundation from outside, are the two keys to stopping the nuisance salts from being present.
Ari Marantz is the owner of Trained Eye Home Inspection Ltd. and a Registered Home Inspector (RHI)(cahpi.ca). Questions can be emailed to the address below. Ari can be reached at 204-291-5358 or check out his website at trainedeye.ca.
trainedeye@iname.com
Renovation & Design
Plants around foundation can impact drainage
Question: With all the water issues in basements last spring, I had some seeping into my basement. In the fall, I piled up dirt around my foundation, to help the water run away from the house. I am wanting to plant something on this dirt so it doesn’t run off with the rain, nor just become weeds. I’m not sure what is best. I don’t want grass, as some areas are hard to get at. I was looking for something that would spread quickly, as there is a lot of piled up dirt along the foundation. Most of it is in the shade, or only gets a couple hours of sunlight in the afternoon. Gout weed would fit the bill, but as it is invasive, I don’t want that. Do you have any suggestions?
Thanks for any help you can give, Beth Wilton.
Answer: Vegetation that is adjacent to your foundation should be chosen for its ease of care and low growth height. Anything that meets those two criteria should be an ideal solution to prevent soil erosion and moisture intrusion.
The first exclusion I would like to note is that I have very little experience with plant nomenclature and science. While a large part of my formal education was in scientific disciplines, I’m afraid I never took anything resembling a botany course. While I will still endeavour to provide an answer to your excellent question, it will nor include suggestions for specific species of plants. For that, a local garden centre, or other plant specialist, should be sought out.
I commend you for taking the correct initial path toward prevention of moisture intrusion into your foundation. A large number of the homes that experience this perennial problem have poor grading around their foundations, which can either cause or exacerbate a seepage issue. This should always be done in conjunction with efforts to route eavestroughs downspouts away from the home, which is usually the largest source of the water that gets inside. Combining your soil buildup with better roof drainage may be enough to negate or minimize the basement leakage so that more serious and expensive repairs are not warranted.
You are exactly correct that the new topsoil you have installed may quickly disappear if you don’t take further measures to hold it in place. Many homeowners opt to install a landscape fabric and stone, mulch, or other granular materials on top, for both aesthetic and practical reasons. That type of covering may work, but it will still require periodic watering and general maintenance to prevent shrinkage of the new soil. The main benefit of that type of soil cover is that it can quickly be done anywhere, regardless of sun exposure, fencing, eave overhangs, or direction. Regardless, planting some form of vegetation is preferable, as it will provide the dual functions of holding the soil in place and maintaining proper moisture content.
As just stated, vegetation will help prevent erosion and disappearance of soil next to your foundation by holding it in place with its roots. Good root structure will also prevent the soil from drying out, as regular watering of the plants will be required to ensure their viability. So, having a complete layer of vegetation immediately adjacent to your foundation will require you to water regularly, which will maintain good soil conditions, unless there is a fair amount of natural precipitation. If there is too much rain, the plants will help absorb some of this excess and also prevent the newly placed earth from washing away.
To directly address your question, the simplest choice would be to plant grass seed, or sod, which is the most common thing to do in this area. You are correct that it may be more difficult to maintain and grow due to the limited sunlight and access. If that is the situation, as it is with many homes, most other types of low vegetation should be an acceptable alternative. Anything that only grows a few centimeters high is ideal, as it will allow access and inspection of the top of the foundation. This is important to monitor for cracks and deterioration, which may also be a cause of spring seepage. As well, the vegetation should be kept to a maximum height, to prevent blocking basement windows, furnace vents, gas meters, air conditioners, and other items in or near the foundation exterior.
Even though I don’t know what “gout weed” is, I agree that you should look for plants that are indigenous, or well established and suited to our Prairie climate. They are usually the easiest to grow and maintain, unlike many types of lawn grasses, which require lots of watering, sun, and often artificial fertilizers, for healthy growth. Whatever you choose it should still require regular watering, which will help remind you to replenish lost moisture in the soil outside the foundation, during hot summer weather. It is doubtful that any type of small plants will negatively affect the concrete foundation, but the inverse may be true. Plants that are resistant to minerals which may leach out of wet concrete or parging, often in the form of salty efflorescence, will be ideal candidates.
Choosing a specific type of plant or plants to grow outside your foundation should take into consideration the growing conditions in the area and composition of the concrete. Any type of vegetation that has a low growth height, is resistant to chemicals leeching from the foundation walls, and requires minimal to moderate watering, may ideally suit the bill for the area outside of your home.
Ari Marantz is the owner of Trained Eye Home Inspection Ltd. and a Registered Home Inspector (RHI)(cahpi.ca). Questions can be emailed to the address below. Ari can be reached at 204-291-5358 or check out his website at trainedeye.ca.
trainedeye@iname.com
