A friend of ours is asking for advice about waterproofing their block wall foundation after their water supply line leaked in their front yard and caused seepage into their basement. The line had been leaking for an extended period and saturated the ground and then with some moderate rain they experienced some slow leakage which resulted in some mold growth in their basement.
They have been asking a few people about the problem and have been quoted some expensive solutions to cure their problem. There is no doubt that any mold that is in the home will have to be killed and that they should find a solution so this problem won’t happen again.
They were lucky enough that they purchased insurance from their water company that covered the cost of repairing the line in their yard. Most home owners do not have insurance that will cover this cost and it can be expensive depending on where the leak is and how bad it became before it was notice. Water supply line leaks normally go undetected for long periods and in some instances can result in sink holes.
Basement Mold Removal
There are a variety of molds that can grow in and around your home. Some of them are very dangerous and other if untreated can result in moderate health problems. If you or someone in your family suffers from lung problems such as asthma you need to take serious precautions and have the mold evaluated and abated as soon as possible. If you are in general health and the problem is small such as only a few square feet then you can normally treat the area with a 50% bleach and water solution by keeping the area wet for 15 to 30 minutes at least with bleach which will kill the mold before you remove it. You should take all proper precautions by wearing respirators and appropriate clothing while doing the work. If you are in any doubt always consult a professional. Additionally any organic materials in the area might need to be discarded such as rugs, furniture, beds or other things that may retain the mold. Again it is always best to get an evaluation before you begin the work whether you hire it out or do it yourself.
Waterproofing Block Wall Foundations
Block wall foundations are treated very much like any other type of foundation when you are trying to waterproof and remove water from around the area.
The first thing in our friend’s situation was that the condition was caused both by highly saturated ground due to the water line break and by rain. Either of these conditions on their own might have caused a problem or may not but both were the cause of his problem. Since the water supply line was repaired the dirt around his home is now not saturated. Additionally the rain that contributed to the problem did not cause leakage along any other wall in his basement. This means that more than likely the problem he had is now gone and the ground around his home will be able to shed water well enough that there is no future problem.
He is however getting contractors recommending two services for his property. One is to install a french drain or perforated pipe around his foundation which will either be piped to a sump pump or directed away from the home. Second is using a vapor barrier in his basement.
Starting with the vapor barrier in the basement. This is probably not a good idea as placing plastic vapor barrier against the perimeter wall of the basement would trap any moisture that passed through the foundation and cause a mold problem. The only way to really prevent water entering a foundation is to waterproof from the outside by digging down and preparing the wall and then applying an Asphalt Emulsion coating and possibly a thick asphalt membrane against the outside of the home. This service can be extremely expensive after a home is built so inspections of homes normally require waterproofing the foundation as it is built.
In this home owner’s case this work is probably not necessary however it would be a good time to inspect the flow of water around the home and if necessary install perforated pipe in the ground under the downspouts of the gutters to remove water from the area of the foundation. Other things can be done like grading the soil around the home so it has a good angle of deflection and will shed water quickly away from the home. Normally an angle that extends at least 4 to 6 feet from the home is a good idea.
Additionally any cracks in the foundation should be repaired and that could mean digging down in a few areas around the home to patch and seal some areas.
Then a water proofing paint should be applied to the interior of the basement foundation wall. This will reduce the amount of moisture that passes through the foundation which will raise humidity levels in the basement causing mold to grow. This is something that the home owner can do after any cracks have been filled with concrete sealer or mortar and any mold present has been treated and removed.
Finally humidity levels should be monitored using a house thermometer that has a humidity readout. You should always expect higher humidity in your basement under normal conditions but if it is too high you can use a dehumidifier to remove the water in the air. This is especially important if the basement is a living area or used as a bedroom.
Final Note
In this How To we covered how to evaluate and repair your basement foundation if water is a problem. In this case the home owner knows that the repaired water supply line in their yard was the primary problem and it has been repaired.
Additional steps to reduce water infiltration may be required but they might not be.
However removal of the mold and control of the humidity levels is a very important immediate step. Proper evaluation of the mold in addition to treatment and then long term prevention by fixing foundation cracks and waterproofing should be done and if necessary a room dehumidifier used.