The term house wrap vapor barrier Energy Star actually covers three topics: house wraps, vapor barriers and Energy Star ratings.
Clearing up the House Wrap Vapor Barrier Energy Star Confusion
- Used on the outside of a home to prevent air leakage, house wraps are installed before the final outside structural materials, like aluminum siding or brick, are installed. House wraps are designed to prevent the air caused by wind from seeping into your home.
- They are permeable, meaning house wraps prevent air from getting into your home but also allow air to escape. If air is not allowed to escape, moisture will occur. This moisture will cause exterior insulation and wood to rot and metal materials to rust.
- Vapor barrier is used on the inside of the home to prevent moisture caused by water vapor. As warm air moves from the inside of your home to the outside of your home, condensation occurs due to the differing temperatures. A vapor barrier prevents the cold air from meeting the warm air (and vice-versa) thereby preventing condensation.
- Vapor barriers are impermeable. The impermeability of vapor barriers prevents condensation from forming by keeping the masses of different temperatures from coming together.
- Vapor barriers are installed before the final inside structural material, like drywall, paneling or bead board, is installed.
To qualify as an Energy Star product, home vapor barriers and house wraps must meet the following standards:
- House wrap must be continuous. The house wrap must cover the entire structure, from top to bottom and be sealed properly.
- Vapor barriers must also be continuous and installed under concrete slabs and on the inside or "warm side" of exterior walls, ceilings and floors.
The Great House Wrap Vapor Barrier Energy Star Debate
Believe it or not, the use of house wraps and vapor barriers are contentious subjects among professional homebuilders and remodeling contractors. Arguments are based on whether and where either one should be used. Everyone agrees that a vapor barrier should be installed on what is called the "warm side" of the wall in an area where the climate varies widely. The "warm side" is just another way of saying the inside. So, put up a vapor barrier on the inside of an exterior wall, before you install the final wall material (drywall, paneling or bead board).
If the climate varies little through the year, there is more debate as to whether a vapor barrier is needed. Some experts will say that in climates where the winters are mild and the summers are hot, vapor barriers are not necessary. Others will say that vapor barriers are necessary due to the humidity in the summer. To further the debate, those that believe that vapor barriers should be used in these areas argue whether it should go up before the insulation or after the insulation but before the final wall material.
Everyone agrees that house wrap should always go on the outside of a home. The debate here is whether house wrap should be used at all. Some experts say that if the house is constructed properly, then house wrap is unnecessary and provides no added value. Experts with this train of thought believe that house wrap materials are very fragile and will begin to deteriorate before the building structure materials.
Others believe that house wrap protects the structural integrity of your house by protecting the building materials from the elements.
Energy Star experts believe that both house wraps and vapor barriers are necessary for the promotion of energy efficiency.
Which Decision is Right?
Some areas like basements should always have a vapor barrier because it is below ground. Other areas, like an interior living room wall, may need a vapor barrier because the temperature between the walls remains constant.In the end, the decision is really up to you. Talk with your contractor about house wraps and vapor barriers, ask other people you may know that have had some experience with both materials and do a little research on your own. Armed with enough information, you will make an informed and educated decision regarding the use of house wraps and vapor barriers.