Most new construction codes in Canada require a drainage material under the slab of the house for water control, the most common being ¾” clean gravel, and a moisture barrier below the slab. Upgrading the moisture barrier to a gas barrier is not a major task and having the drainage material and gas barrier in place allows a passive stack or a fan to create a far reaching field of depressurisation under the slab. The rough-in sub-slab piping is inexpensive as well. Hence requiring every house to be built as what is called “Readily Remediated New Construction” is a very practical and inexpensive requirement allowing for some reduction of radon in all houses and total control of radon where it is deemed necessary after the house is occupied. But what is done below the slab must be planned and installed as part of a larger system. This is the first of four technical radon videos.
Resources for work under the slab.
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