Measure the attic floor or the surface where you'll install the barrier and cut the material to fit, leaving an overlap of 6–12 inches between pieces. Lay the vapor barrier flat over the surface. Staple it securely to the joists or framing, spacing staples about 12 inches apart.
In colder climates, where the home's heating system sees more use, the vapor barrier should typically be installed on the insulation's interior side. In warmer climates, where the home is often kept cooler, the vapor barrier should usually be installed on the exterior side.
Provided you're not claustrophobic, installing a vapor barrier is a project most homeowners can DIY. You will need to calculate the square footage of your crawl space, so you can buy the appropriate amount of liner.
In cold climates, vapor barriers go on the warm side of insulation. In hot, humid climates, they go on the exterior side. Even with faced insulation appropriately installed, it's wise to have a separate vapor barrier facing the heated space. This layer adds extra moisture protection.
Do I Have To Remove Old Insulation? Unless your insulation is wet, moldy or infested with pests, you don't need to remove it before adding insulation on top of it. ENERGY STAR® recommends that you inspect your insulation for signs of mold, mildew, moisture and pest infiltration before making this determination.
It is possible to over-insulate your house so much that it can't breathe. The whole point of home insulation is to tightly seal your home's interior. But if it becomes too tightly sealed with too many layers of insulation, moisture can get trapped inside those layers.
Also, when laying down additional insulation, work from the perimeter toward the attic opening. Never lay insulation over recessed light fixtures or soffit vents. Keep all insulation at least 3 inches away from recessed "can" lights, unless they are rated IC (Insulated Ceiling).
Extend vapor retarder at least 6 inches up walls, columns, and footings. Use physical attachments where practical and necessary for long-term adhesion of vapor barrier to vertical surfaces. Overlap all seams at least 12 inches using a reverse or upslope lapping technique.
You can use faced or unfaced batting when installing between the roof rafters of finished attic spaces. When using paper or plastic batting insulation, that moisture barrier should face outward toward the attic space. Even if the attic space is unheated, it's typically warmer than the outside air in winter.
Because a vapor barrier is a low permeable barrier, it keeps moisture from passing through. This is beneficial to keep moisture away from a dry surface but will trap moisture behind it if installed on a water-damaged concrete wall, causing the wall to fail further.
Materials such as rigid foam insulation, reinforced plastics, aluminum, and stainless steel are relatively resistant to water vapor diffusion. These types of vapor retarders are usually mechanically fastened and sealed at the joints.
Very often, particularly in a below-grade installation on a concrete basement floor, a vapor barrier is recommended in addition to the underlayment. That vapor barrier would go between the subfloor and the underlayment.
Can I put plywood over insulation in the attic? Yes you can install plywood subflooring directly over the floor joists and insulation on your floor. You need to install rigid insulation boards on top of the attic flooring joists and then install plywood over the top.
Yes, an air gap can significantly improve the effectiveness of insulation. This is because air is actually a good insulator in itself.
Yes, covering your insulation with a vapor barrier plastic before installing drywall is crucial. It prevents moisture buildup that can lead to mold, rot, and even structural damage. A polyethylene vapor barrier also adds a layer of fire protection, making your home safer.
Attics and Ceilings: In attics, vapor barriers can be placed on the floor to prevent moisture from rising into the attic space from the living areas below. In certain designs, especially in colder climates, a vapor barrier may also be used in ceilings to prevent moisture from passing into the attic.
DIY Vapor Barrier Installation
DIY installation can offer cost savings and the satisfaction of completing the job yourself. However, it requires a good understanding of your home's moisture control needs and the ability to properly seal the barrier to prevent leaks.
Is DuPont™ Tyvek® a vapor barrier? No, DuPont™ Tyvek® is not a vapor barrier. It is made with unique material science to keep air and bulk water out while allowing moisture vapor inside walls to escape.
Some studies show that radiant barriers can reduce cooling costs 5% to 10% when used in a warm, sunny climate. The reduced heat gain may even allow for a smaller air conditioning system. In cool climates, however, it's usually more cost-effective to install more thermal insulation than to add a radiant barrier.
Looking across your attic, if the insulation is level with or below the attic floor joists, you probably need to add more insulation. If you cannot see any of the floor joists because the insulation is well above them, you probably have enough, and adding more insulation may not be cost-effective.
The best way to insulate the inside of a ceiling depends on the type of ceiling and your specific needs. Spray foam insulation and batt insulation are two popular options. Spray Foam Insulation: This method involves spraying a liquid foam that expands and hardens.
The recommended level for most attics is to insulate to R-38 or about 10 to 14 inches, depending on insulation type.
If your attic has little or no existing insulation, you'll want to install an R-38 rated material. If your attic has 2-3″ of existing insulation, you'll want to install an R-30 to achieve a total of R-38. If your attic has 5-6″ of existing insulation, you'll want to install an R-19 to achieve a total of R-38.
When loft insulation is added, it can make the loft space cooler by preventing warm air from rising into it. This cooler environment can lead to condensation when warm, humid air from the house rises and comes into contact with the cooler surfaces in the loft.