Putting Plastic Sheeting Over Insulation

Plastic on the outside.

Putting plastic sheeting over insulation.

If you want to put something on the bottom of the joists to hold the insulation in place use chicken wire landscape fabric or housewrap so any water vapor from inside the house can escape. If you re referring to insulation in an attic you shouldn t put plastic sheeting over the top of it either for the same reason. Picture an ice cold can of soda on a sweltering hot day. Plastic on the outer surface of a wall in cold weather could cause problems.

How to install poly over insulation. Install the plastic sheeting only after the insulation wiring and plumbing have been completed. Homeowners use plastic to cover their crawl spaces to control moisture and create a barrier against vapor. Item 491792 model hslw12 400.

After the insulation is installed it is necessary to cover it up with a vapor barrier so the glass fibers are not inhaled. 12 ft x 400 ft clear 0 31 mil plastic sheeting. The humid air is indoors. Soon water pours off the can.

Overlapping paper tabs on faced insulation and stapling is why its on there. Without such a barrier condensation can infiltrate your home s walls and insulation creating a substantial risk of mold and mildew. The plastic and the insulation will eliminate any moisture problems you have in the crawlspace such as water droplets collecting on the concrete walls. Plastic sheeting can also help turn a crawl space into a usable storage area.

More use the plastic these days without paper faced insulation. Most insulation is made of fiberglass and fits into the walls between the studs before drywall is installed. The best vapor barrier to use is roll of plastic sheeting. To each is own some believe the plastic works better.

If water vapor diffuses or infiltrates into the wall cavity and finds the cool surface moisture problems can occur. The cool surface is the sheathing assuming no exterior insulation. Stretch the plastic sheet tightly across the top of the wall and staple it to the studs and plates. Paper faced insulation is the same as using plastic vapor.