Sunday, January 18, 2009

waterproofing the basement

The first concern was that the almost one hundred year old home had the usual porous concrete foundation walls. The original builders had used unclean river rock as the aggregate and no reinforcing as was customary at the time. Over the years, this type of wall weakens, as evidenced by the hairline and large cracks in our foundation walls. There were also a few areas where the wall was soft and crumbly due to poor drainage from the gutters and downspouts. Although the amount of water coming in was never substantial, it was enough to raise concern for the basement build-out.

We interviewed several water mitigation contractors. Each proposed a different method of addressing the infiltration. Our preferred choice was to install an exterior french drain and drywell, but we could not locate the drywell without the undue cost of tearing out trees and digging up an oil tank or ripping up a deck and paving stones.

In the end, Western Construction Systems sealed the larger cracks with expanding foam, patched all cracks, skim-coated the walls, replaced the exterior drain lines that were clogged with debris, installed a sump pump with interior drain along the perimeter walls and applied a two-part epoxy paint on the foundation walls and floor. We then waited for the heavy winter rains to test the system. Mother Nature complied with record snow- and rainfall over the holidays, and the basement remained dry. We were finally ready to start! Whoohoo!

Tune in next time for the benefits of design prior to construction!

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