Which material is an example of acceptable waterproofing material for foundation walls?

Which material is an example of acceptable waterproofing material for foundation walls?

• A. Plywood
• B. 6-mil polyethylene
• C. Painted drywall
• D. Aluminum foil

Answer: (B)

The key idea is that foundation wall waterproofing must create a continuous, non-porous barrier to keep moisture from penetrating the wall assembly. A sheet of 6-mil polyethylene fits that role because it’s a plastic film that resists water and can be laid as a continuous sheet with overlapped seams sealed to block water paths. When installed correctly, it provides a straightforward moisture barrier behind or on the exterior of basement walls. Plywood isn’t suitable because it’s a wood product that will rot, warp, or deteriorate when exposed to soil moisture and water, so it can’t serve as a reliable waterproofing layer. Painted drywall is an interior finishing material used inside the building and is not designed to stop water from entering through foundation walls; moisture would damage it and allow infiltration. Aluminum foil isn’t used as a primary waterproofing membrane for foundation walls because it’s thin, prone to tearing, and does not provide a durable, continuous seal needed to prevent seepage. So, among the options, the 6-mil polyethylene sheet best serves as a waterproofing barrier for foundation walls when installed with proper seam overlaps and sealing.

The key idea is that foundation wall waterproofing must create a continuous, non-porous barrier to keep moisture from penetrating the wall assembly. A sheet of 6-mil polyethylene fits that role because it’s a plastic film that resists water and can be laid as a continuous sheet with overlapped seams sealed to block water paths. When installed correctly, it provides a straightforward moisture barrier behind or on the exterior of basement walls.

Plywood isn’t suitable because it’s a wood product that will rot, warp, or deteriorate when exposed to soil moisture and water, so it can’t serve as a reliable waterproofing layer. Painted drywall is an interior finishing material used inside the building and is not designed to stop water from entering through foundation walls; moisture would damage it and allow infiltration. Aluminum foil isn’t used as a primary waterproofing membrane for foundation walls because it’s thin, prone to tearing, and does not provide a durable, continuous seal needed to prevent seepage.

So, among the options, the 6-mil polyethylene sheet best serves as a waterproofing barrier for foundation walls when installed with proper seam overlaps and sealing.