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Re: Foundation drains

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Thanks Paul,
Actually one of the renowned experts in the field, Peter Craig, agrees with that.  He says that it doesn't matter if the water table is 10 feet or 510 feet deep, once the slab is covered with a low-permeance flooring material, moisture beneath the slab will increase over time and most often reach close to 100% relative humidity.

Do you know if there is any requirement in the US codes?

On Fri, Nov 5, 2010 at 12:30 AM, ad026 rpransom <ad026(--nospam--at)> wrote:
over my career I have waffled back and forth on the need for foundation
drains at the footing for any particular circumstance (e.g. basement or not,
foundation below frost line or not). If there is a below grade story
(basement) it is essential. I think that it is always a good practice if for
no other reason than to mitigate deterioration of the foundation materials
(e.g. concrete and rebar, wood, ICF). However, there has to be someplace to
dispose the drain water (e.g. municipal storm drain, cistern, sump).

Vapour pressure will always exist above the water table, regardless of
whether that is 1' or 5' feet below the slab ... make sure the vapour
retarder is there.

Paul Ransom, P.Eng.

> Are there any building officials on the list now, someone like Scott Hahn,
> who knows very well the US codes ?
> I am trying to find out if there are any provisions in US codes, or Indian,
> English or other codes also, that make a foundation drain obligatory.
> There is such a provision in the Canadian National Building Code, Part 3,
> Moisture and Thermal Protection, and I am trying to determine if it is a
> logical requirement or just something that developed in a country that
> almost always uses basements.
> Some "experts" have determined that the lack of a foundation drain may be a
> contributing factor in a vapor transmission problem through a SOG that is
> causing floor finishes to blister.  The real experts who have published
> research on the subject all point to the missing vapor barrier, but you know
> what lawyers can do with the truth.
> Any help and information on any country's codes would be appreciated.

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