We have a concrete deck that sits about 6 ft. high from the ground. It has tar paper attached underneath on bottom. Would this not cause the concrete to break down from moisture?
With out knowing the year the concrete deck was built but tar paper was used to separate the concrete from forms. Often it was just left in place after the forms where removed. But in saying that, tar paper is Pouris and water vapour would evaporate away. Sometimes if the tar paper gets wet during a freeze and thaw cycle it can cause surface damage to the concrete where you will see the concrete surface starting to flake away.
At that point the tar paper should be completely removed.
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