How to Install a Ground Vapor Barrier Under a Manufactured Home

Although little aluminum-clad trailers still ply the highways on summer vacations, truly mobile homes have blossomed in size and manufactured homes in planned communities are mobile only when a semi truck backs them into position or pulls them away. When a house becomes semipermanent, it requires vapor barriers similar to those installed in homes with crawl spaces. The U.S. Department of Housing and Urban Development sets standards for these barriers.

6 mil polyethylene sheeting
Duct or other waterproof tape
Utility knife
Scissors

Instructions

- 1
  Purchase enough 6 mil-thick polyethylene sheeting to cover the area under your home. Seams must overlap 12 inches and extend around footings, so add extra sheeting to your estimate. Vapor barriers need not be installed under decks but should be laid under enclosed or indented porches.
- 2
  Roll the sheet out evenly over the home's gravel base with a 4- to 6-inch overhang beyond the edges where the skirting will land. Overlap any seams by a minimum of 12 inches and tape them with duct tape.
- 3
  Cut to fit and tape the sheeting around the piers. If piers have not yet been installed, lay the sheeting without cutting; barrier sheeting can be installed under piers also. Wait to trim the sheeting that hangs out beyond the edges until skirting is installed as skirting installations vary.

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