After the heavy snows of 2013/14, Southern Ontario experienced one of the highest water tables in recent memory. In some townships, half load limits for the aggregate haulers was extended for 15 days. Then it rained more than a builder would expect. Easy to tell when looking out over the shoreline of Georgian Bay.

Our first project of the spring was to build a beautiful custom cottage in an area just north east of Collingwood, in an area that is known for having a high water table. On this particular piece of property, we were unaware of just how high the water was from the surface until the excavator dug out the test pit for the septic bed. Our estimate was that the base for the footings were one foot above the water table.

This news was a bit unsettling for our client but they were determined to move forward with their dreams. The lot was in an area of childhood memories for them and they wanted to give their son the same opportunities to have similar experiences.

Proceeding Custom Home Build on High Water Table

After a lengthy consultation with the local building department, we engaged an Architectural Engineer to test the base of the Native Soil (undisturbed). They then determined the changes that would need to be made to the footing sizes, drainage plans, and waterproofing. These requirements were then identified on stamped drawings that were provided to the Town office for approval.

The Engineers also monitored the construction to verify that the listed requirements were met by Alair, and their findings were sent to the Building Department to prove that we are in compliance with the requirements.

In point form, here is the list of items that were required:

• Oversize the footings in the areas of increased loads. Ie: beam transfer points
• Use of Rebar in these same areas
• Rebar was used to tie the heaviest point loads to the concrete floor as well
• Additional 4” drainage pipe was placed in the interior of the footing as well
  as the exterior
• 6 mil poly was placed over the entire gravel base of the floor, all joints taped
• Waterproofing material was applied to the foundation (as opposed to damp proofing)
• Specialized dimpled membrane with an interior filter cloth was applied to the entire foundation, allowing for drainage inside the membrane
• Additional gravel placed on exterior drainage pipe
• Special care was used when backfilling and finished grades were achieved with a specific 2% fall away from the foundationOne major concern was the amount of work that the sump pump was going to get, so we had the excavator dig a trench from the footing drains out to a low point at the side of the lot. We were fortunate that this property had a gradual slope towards the side lot.I guess the real test will come in the spring when the water table will rise again, but today (and its raining again) the floor is dry and the sump pump is quiet. Good signs of success from the extra effort that our team at Alair has put into this foundation.