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Before Finishing a Basement

Check your TARION Warranty

Currently, in Ontario, the TARION New Home Warranty protects against water penetration through the basement or foundation walls for 2 years from the date the first owner takes possession. If you have a new home but haven’t yet finished the basement, you should determine whether there is any moisture incursion, either through the foundation walls or the concrete floor slab. You should do this before your warranty expires and certainly before you start finishing your basement. Repairing faulty foundation waterproofing or weeping tile installations can be very expensive.


Is That Mold or Mould?

Spelled either way, if it refers to a moisture loving fungus, you don’t want it growing in your home. Whether you have newer or older construction, installing insulation and a vapour barrier over damp foundation walls can lead to a build-up of toxic fungi. The same goes for finishing damp basement floors.


Check for Moisture.

Before finishing your basement, perform this simple test to see how well your foundation waterproofing and weeping tile systems are performing. In a few locations, securely tape 12” x 12” squares of clear plastic film to the inside surface of the exposed masonry walls, a few inches above the basement floor. Ensure that each square is completely sealed around its perimeter. Do the same in a couple locations on the concrete floor.


This test allows you to determine whether any moisture is the result of water coming through the masonry and not simply warm air condensing on cold concrete surfaces. After 24 hours, check to see whether any moisture has accumulated between the plastic and the masonry.


You may need to perform this test at different times of the year, as ground water levels in places such as Kingston, Amherstview and Bath, fluctuate with rainfall and snow melt. Also, indoor humidity levels vary, depending on whether you are heating or cooling your home.


Partially Finished Basements.

If the exterior basement walls of the house you just bought have bat insulation and a vapour barrier installed without any drywall, this would be a good time to check for moisture before closing up the walls. You don't want to close in a potential mould problem. Simply cut a 12" horizontal slit in the vapour barrier about 12" above the floor. Then push the insulation up inside the joist cavity and ensure that it, the wood studs and the masonry wall are all dry. If there is no moisture present, reposition the insulation and reseal the vapour barrier with sheathing tape.


However, if you discover that the insulation is damp or that there is moisture on the exposed masonry wall or studs, you'll need to remove the vapour barrier and the insulation to check for the presence of mould. If your TARION warranty is still in effect, this would be a good time to contact the builder. If the warranty has expired and there is mould present, you should consider hiring a remediation service to test and safely remove the affected materials.


Once you have gotten rid of the mould, you will need to determine whether moisture in your basement is being caused by condensation, a leak or both. Dry the masonry wall with a fan, secure some clear plastic film directly over it, then check for any moisture incursion the next day. If there is only a small amount of moisture entering through the masonry, occasionally running a dehumidifier may be enough to get rid of it and avoid musty smells. However, if there is significant moisture present, this will likely require the services of a basement waterproofing specialist.


Wet or Damp Basements - Contributing Factors

Half the solution to a problem lies in understanding the problem. The age of your home, quality of construction, the condition of the foundation waterproofing system along with the weeping tile and the level of the water table in your area are all factors which contribute to how dry your basement will be.


Do you have a sump pit and pump? Is the pit always full? How often does the pump run? Is it and your weeping tile connected to a municipal sewer service? If you are pumping a lot of sump water into a septic tank, you may run the risk of overwhelming the system. Is your sump being pumped far enough away from your house to a lower lying area, or are you simply recirculating the ground water?

Armed with the answers to these questions, you'll be in a good position to determine what remedial action you may need to take.