Vapor Barrier Installation in Montgomery, AL

A vapor barrier is a sheet of plastic installed over the soil in a crawl space to prevent ground

moisture from rising into the home. In Montgomery, Alabama, where humidity is high

year‑round, vapor barrier installation is essential for protecting floor joists, reducing mold, and

improving indoor air quality.

Why Montgomery Homes Need Vapor Barriers

Bare soil in a crawl space continuously releases moisture vapor. In Montgomery’s humid

climate, this can raise the relative humidity in the crawl space to 80‑90%. That moisture

condenses on cool floor joists, leading to rot, mold, and musty odors. It also increases

humidity in your living space, making your air conditioner work harder. A vapor barrier blocks

upward vapor flow, keeping the crawl space drier. Montgomery Foundation Repair Co

recommends a vapor barrier for every crawl space that does not have one.

Types of Vapor Barriers

Vapor barriers are rated by thickness in mils (thousandths of an inch). The minimum

recommended by building codes is 6 mil, but this is thin and easily torn. A better choice is

10‑12 mil, which is more durable. For high‑traffic crawl spaces (used for storage or with

mechanical equipment), 20‑mil reinforced polyethylene is best. Montgomery Foundation Repair

Co uses 12‑mil or 20‑mil barriers, with seams taped or heat‑welded for an air‑tight seal. We do

not use 6‑mil film except for temporary applications.

Professional Installation Steps

Installing a vapor barrier correctly is more than just rolling out plastic. Montgomery Foundation

Repair Co starts by removing debris and sharp objects from the crawl space floor. We then lay

the barrier in overlapping sheets, with at least 12 inches of overlap at seams. We tape or weld

the seams. The barrier extends up the foundation walls at least 6 inches and is mechanically

fastened. We also seal around pipes, posts, and other penetrations. The result is a continuous

barrier that covers the entire crawl space floor. Installation typically takes one to two days.

Vapor Barrier as Part of Encapsulation

A vapor barrier alone is not full encapsulation. Encapsulation includes sealing the barrier to the

walls, closing vents, and adding a dehumidifier. If your crawl space is already dry and you just

want to reduce humidity, a floor‑only vapor barrier may suffice. But for maximum protection

and energy savings, Montgomery Foundation Repair Co recommends full encapsulation. We

can upgrade any existing vapor barrier to a full system.

Frequently Asked Questions