Radiant barriers are installed in homes -- usually in attics -- primarily to reduce summer heat gain and reduce cooling costs. The barriers consist of a highly reflective material that reflects radiant heat rather than absorbing it.
If you decide to install a radiant barrier, the best place to install it would be on the underside of the rafters (with an air space between the radiant barrier and the roof sheathing).
Where Should a Radiant Barrier Be Installed? Radiant barriers are most commonly installed in the attic, where they can effectively reflect heat away from living spaces. The attic is the primary location because it is where the most significant temperature difference between the inside and outside of the home occurs.
Tip 3: Determine the most vulnerable side – When installing insulation with a vapor barrier, the vapor barrier should usually be applied on the side of the insulation that's closest to where it will be exposed to the most warmth and moisture.
Radiant barrier sheathing panels have two sides: a foil surface and a skid-resistant surface. LP TechShield panels should always be installed with the foil side down and the skid-resistant side facing up.
Simply put, the biggest possible problem with any kind of radiant barrier is dust. To understand why dust creates issues for all kinds of radiant barriers, it's important to understand how they work: Radiation transfers heat directly outward from an energy source.
Vapor Barriers
The facing of the insulation serves as a vapor barrier. Vapor barriers resist moisture penetration, keeping humid interior air from reaching cold surfaces where it could condense. In cold climates, vapor barriers go on the warm side of insulation. In hot, humid climates, they go on the exterior side.
Vapor barriers are installed along, in, or around walls, ceilings, and floors. Of course this is done to prevent moisture from spreading and potentially causing water damage.
One important thing to remember is that insulation should never be pushed right into the eaves because it will interfere with airflow. If you're going for a warm loft then you'll need much more insulation to be able to cover the underside of the roof along with the gable and party walls.
This is because an air gap provides an additional layer of insulation that helps to prevent heat from passing through the barrier and into the living space. If you are installing a radiant barrier, it's recommended to leave an air gap of at least 25mm (1 inch) between the barrier and the surface it's installed on.
The tests to date have shown that in attics with R-19 insulation, radiant barriers can reduce summer ceiling heat gains by about 16 to 42 percent compared to an attic with the same insulation level and no radiant barrier.
Radiant barriers may be installed in attics in several configurations. The simplest is to lay the radiant barrier directly on top of existing attic insulation, with the reflective side up.
Alternatively, you can place one radiant barrier above your attic ceiling insulation and a second one below to maximize the beneficial effects in both summer and winter. Whichever approach you choose, don't allow any dust to accumulate on top of the reflective surface during the installation.
The air barrier may be installed on the interior side of the insulation, the exterior side of the insulation, or both, depending on the building component and the climate.
Installing a radiant barrier costs $1,700 on average, but often ranges between $710 and $2,840 depending on whether your pro uses a foil or spray on type.
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).
Should I remove old loft insulation before laying new? Older insulation material will typically need to be removed before adding new insulation. However, in some cases the material may be in good condition, meaning you can simply top up the existing insulation material for a fraction of the cost of a full replacement.
One way that excessive loft insulation can cause dampness is by blocking ventilation. Proper ventilation is necessary to allow moisture to escape from the building. If insulation is installed too thickly or packed too tightly into the loft, it can block air flow and prevent moisture from escaping.
A vapour barrier is placed on the inner side of the insulation and is designed to stop moist air from passing through it. A breathable membrane, by contrast, is installed on the outer side of the insulation. Breathable membranes must repel water from the outside while still allowing moisture from the inside to escape.
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.
They perform best when installed closest to the warm side of a structural assembly -- toward the interior of the building in cold climates and toward the exterior in hot/wet climates. Vapor retarder installation should be continuous and as close to perfect as possible.
In cold climates, the barrier goes on the warm (interior) side of the insulation. In hot, humid climates, it's placed on the cool (exterior) side. Under flooring: When installing wood flooring over concrete, a moisture barrier protects the wood from moisture damage.
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.
Install a New Vapor Barrier
If your vapor barrier was damaged or not installed correctly, it's important to replace it with a new one. This will help prevent moisture from seeping into your crawl space and creating the perfect environment for mold growth.