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Vapor Barrier Requirement for Basement Concrete Walls

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Chuck_M

Registered User
Joined
Feb 11, 2022
Messages
26
Location
Charleston, South Carolina
Hello Everyone,

I live in Charlotte, NC and I'm trying to look up in the building codes if it is required to have a Vapor Barrier on concrete walls in the basement. I keep finding requirement for concrete slabs but nothing on the walls.

Can someone help me locate the requirement?

Thank you
 
I will suggest that even if not required by the building code that you will still wnt to install waterproofing on the basement wall.

The building code does not address everything that you should do.
 
The builder put vapor barrier on 2 out of the 3 walls.. I do not understand why, I check the moisture sensor on the drywall and opened the drywall to confirm this. Builder says they are following code and if code stated they needed vapor barrier they will put it. So I just need to find that part of the code.
 
Not so much a code answer but a decent treatise on the subject. You can compare what you've got to this.

BSI-125: Concrete Basement Foundations

One of the most common foundation approaches to residential construction are concrete basements. They can be insulated on the inside or the outside. The basis of all basement foundations . . .
www.buildingscience.com www.buildingscience.com

In my mind, you want the impermeable layer on the exterior of the foundation ("damp proofing") and do not want it on the interior side of any basement wall insulation. Basements can really only dry in.
 
Regardless of climate zone, concrete basement walls should be waterproofed (exterior, below grade side of the wall) and a vapor barrier should never be installed on the interior face (the exposed or furred framing wall).

Concrete will never completely dry out and will absorb and release vapor throughout its life. Placing a vapor barrier on the interior side of the wall will trap this moisture and can lead to mold or rot.

It is proper to waterproof the exterior buried face of the wall. Curtain drains, proprietary systems, clay fabrics, and bituminous emulsions are all common methods of waterproofing a basement wall. The intent being to prevent the concrete wall from absorbing the water from the soil and having it wick through the wall and into the home.
 
SECTION R406
FOUNDATION WATERPROOFING AND
DAMPPROOFING
R406.1 Concrete and masonry foundation dampproofing.
Except where required by Section R406.2 to be waterproofed,
foundation walls that retain earth and enclose interior spaces
and floors below grade shall be dampproofed from the higher
of (a) the top of the footing or (b) 6 inches (152 mm) below the
top of the basement floor, to the finished grade. Masonry walls
shall have not less than 3/8-inch (9.5 mm) Portland cement
parging applied to the exterior of the wall. The parging shall be
dampproofed in accordance with one of the following:
1. Bituminous coating.
2. Three pounds per square yard (1.63 kg/m2) of acrylic
modified cement.
3. One-eighth-inch (3.2 mm) coat of surface-bonding
cement complying with ASTM C887.
4. Any material permitted for waterproofing in Section
R406.2.
5. Other approved methods or materials.
Exception: Parging of unit masonry walls is not required
where a material is approved for direct application to the
masonry.
Concrete walls shall be dampproofed by applying any one
of the listed dampproofing materials or any one of the waterproofing
materials listed in Section R406.2 to the exterior of
the wall.
R406.2 Concrete and masonry foundation waterproofing.
In areas where a high water table or other severe soil-water
conditions are known to exist, exterior foundation walls that
retain earth and enclose interior spaces and floors below
grade shall be waterproofed from the higher of (a) the top of
the footing or (b) 6 inches (152 mm) below the top of the
basement floor, to the finished grade. Walls shall be waterproofed
in accordance with one of the following:
1. Two-ply hot-mopped felts.
2. Fifty-five-pound (25 kg) roll roofing.
3. Six-mil (0.15 mm) polyvinyl chloride.
4. Six-mil (0.15 mm) polyethylene.
5. Forty-mil (1 mm) polymer-modified asphalt.
6. Sixty-mil (1.5 mm) flexible polymer cement.
7. One-eighth-inch (3 mm) cement-based, fiber-reinforced,
waterproof coating.
8. Sixty-mil (1.5 mm) solvent-free liquid-applied synthetic
rubber.
All joints in membrane waterproofing shall be lapped and
sealed with an adhesive compatible with the membrane.
Exception: Organic-solvent-based products such as
hydrocarbons, chlorinated hydrocarbons, ketones and esters
shall not be used for ICF walls with expanded polystyrene
form material. Use of plastic roofing cements, acrylic
coatings, latex coatings, mortars and pargings to seal ICF
walls is permitted. Cold-setting asphalt or hot asphalt shall
conform to Type C of ASTM D449. Hot asphalt shall be
applied at a temperature of less than 200°F (93°C).
 
Damp proofing- a layer (liquid, sheet, etc) that protects the foundation walls from moisture ingress by interrupting capillary action.
Vapour barrier- a layer (typically sheet, sometimes rigid insulation) that protects the wall or roof assembly from water vapour in the air.

Chuck-M, which are you speaking of? Sounds to me you are looking at the interior vapour barrier
 
Agree with classicT. See IRC R702.7. Basement walls and below-grade portions of any wall are exempt from vapor retarder requirements, and I think that's, as classicT says, because there's no way to keep moisture out of concrete and you don't want to trap moisture within an assembly.
 
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