After deciding to install radiant barrier you need to decide which installation method is best for your home. There are two main criteria that should influence your decision: 1) Your climate area and 2) Whether you have ductwork in the attic.
The two most common methods of installing radiant barrier are to either staple the radiant barrier attic foil to the bottom of your roof rafters or lay out the radiant barrier foil insulation over your existing batt or blown in attic insulation.
If you live in a cold or mixed climate, laying the radiant barrier across the attic floor insulation is the easiest and most effective. In the Summer it will reduce radiant heat gain into the home and in the Winter it will reduce heat loss by radiation and minimize convective looping. That is, it reduces the cold heavy air falling through the attic insulation and combining with the warn air rising to the ceiling forming the loop. This will reduces the R Value of the attic insulation. Remember, foil insulation is NOT a substitute for regular attic insulation. They work together to reduce both radiant and conductive heat flow.
If you live in a warm or hot climate and have NO ductwork in the attic, then go ahead and lay the radiant barrier attic foil on top of your existing insulation. This is the best option for reducing both Summer heat gain and Winter Heat Loss. Make sure you have adequate insulation BEFORE adding radiant barrier. Once the radiant barrier is put over the blown in insulation you cannot put more insulation on top. This will eliminate the benefit of a radiant barrier, which requires an air space on one side of the foil to be effective.
If you DO have ductwork in the attic, then consider the staple up method. When you think about it, putting ductwork in the attic is like making ice cream in the oven. Not really smart. By stapling the foil to the bottom of the rafters you will get the benefit of reducing radiant heat gain into the attic insulation AND reducing the attic temperature. By reducing the attic temperature, less heat will be transferred INTO the ductwork by conductive heat flow. Plus, it’s very cool to walk into your attic on hot Summer day and it feel tolerable compared to being inside of an oven.
Either radiant barrier install method works well. In colder climates, laying across the attic insulation is the way to go. In warm/hot climates it’s a decision of what’s easiest verses what is best. Putting the radiant barrier foil over existing insulation is usually the easiest and works great. Stapling to the bottom of the roof rafters will create a cooler attic, put the ductwork in a less hostile environment AND reduce radiant heat gain into the home. The staple up method results in the least overall heat gain into the home. Both radiant barrier install methods will make your home more comfortable and save you money on your utility bills.
Author Resource:
Ed Fritz is the owner of http://www.AtticFoil.com . His passion is to help homeowners make their homes more comfortable and energy efficient. He has helped literally thousands of customers by sharing his first hand experiences using radiant barrier foil. For more http://www.radiantbarrierguru.com