Damp proofing for deck pilasters
I have 9 20″x20″x96″ concrete pilasters on footings to be used as supports for my deck and the columns supporting the roof over that deck. Some of these are almost entirely below grade while others are primarily above grade. Do these pilasters need any sort of damp proofing to prevent freeze/thaw spalling? This is a new-build that will have appropriate drainage in Denver, CO in sandy/clay soil.
My opposing thoughts on this subject are:
Pilasters are damp proofed but rising damp will allow moisture into the columns from their footings and the damp proofing will not allow them to dry to the soil which will allow the moisture to freeze and crack the concrete.
Pilasters are not damp proofed and rising damp plus moisture in the soil will penetrate the concrete allowing the moisture to freeze and crack the concrete.
I am a newbie to construction but am eager to learn. Which of these scenarios is accurate?
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Replies
Tony,
Are you talking about cylinders of concrete formed with Sonotubes?
Assuming that the concrete was properly mixed and placed, the concrete won't be harmed by freezing temperatures or exposure to moisture. My concrete posts (formed in Sonotubes) look fine after 35 or 40 years.
No sonotubes used. They are actually square mini foundations made with traditional foundations forms and placed on footings. Thanks for the input. The engineer didn't spec any damp proofing for the pilasters (just the foundation walls adjoining living space) but I wanted to make sure before we backfill tomorrow.