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RE: Foundation drains

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The issue of blistering of floor surface finishes on slabs on grade is a serviceability issue.  And there are specific requirements contained in the building codes.  Moisture ingress can cause mold and air quality issues and should not be ignored.  A search on the WBDG on NIBS web site will provide very good guidance.  Many floor finishes are sensitive to moisture vapor ingress through slabs on grade.  I would opt for using a vapor barrier in most situations because it does not cost that much to install and there will probably be changes of use in the future.  I would rather have it and not need it than need it and not have it. 
....Back to your initial question.  The current IBC-09 requires foundation drains as cited in section 1805.  IBC-03, and 06 had it in section 1807.  IBC-00 had it in 1806.  BOCA 96 had it in section 1813.  UBC had some stuff stuck back in the appendix where no one looked.  Some measure of moisture control has been around a long, long time. 
2009 IBC Section:



1805.1 General. Walls or portions thereof that retain earth and enclose interior spaces and floors below grade shall be waterproofed and dampproofed in accordance with this section, with the exception of those spaces containing groups other than residential and institutional where such omission is not detrimental to the building or occupancy.

Section 1805.4 gets into "foundation drains".  So if your floor is below grade, there is no IBC wiggle room.  If the floor is at or above grade, you have a lot of wiggle room.  This section is a pretty heavy duty hammer contained in the IBC.  Since we structural engineers show the slabs-on-grade, we had better show what is written in the the IBC.   
By the way, in the legal world this e-mail is "discoverable".  Things I have posted on this forum have been presented in real cases.  If you have an issue and want to stay under the legal eagle radar, be careful about what goes out on open forums.    

Regards, Harold Sprague


Date: Tue, 9 Nov 2010 21:31:43 -0500
Subject: Re: Foundation drains
From: kbofoz(--nospam--at)
To: seaint(--nospam--at)

It appears that no-one knows about such a requirement, but I would really appreciate even negative replies if you can please.

On Mon, Nov 8, 2010 at 9:36 PM, Kevin Below <kbofoz(--nospam--at)> wrote:
Joe and Paul, are you aware of any US code requirement for a perimeter foundation drain ?  How about Vish in India ?

On Fri, Nov 5, 2010 at 3:10 PM, Joe Venuti <jovenengr(--nospam--at)> wrote:

Vapor barriers are required in habitable space only.


Joe Venuti,  P.E.

Joven Engineering

La Quinta,  CA


From: Kevin Below [mailto:kbofoz(--nospam--at)]
Sent: Friday, November 05, 2010 9:51 AM
To: seaint(--nospam--at)
Subject: Re: Foundation drains


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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