Flat-Top Radiant Barrier Installation Instructions
The FlatTop Method answers the question “How Am I Going To Get Foil Way Up There To The Top Of My Attic"?
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The good news is you don’t have to get the foil to the top of the attic to be effective. We developed the FlatTop method to make installations in tall attics easier, faster and safer.
The "FlatTop" method is the ideal radiant barrier installation method for both high pitch-hard to reach attics and standard type attics. The basic system creates a "false ceiling" that will act as flat surface to hold radiant barrier foil across the top part of the attic. This makes access within easy reach for even the tallest attics. You do not have to create any ventilation and can essentially create a "room within the attic" made of radiant barrier reflective foil. Combined with proper attic ventilation, radiant heat will be reflected back towards the roof. Ventilation from the soffits to the ridge (top area) will allow the heat to be channeled out. Even on the hottest day, the space within the foil cavity should be just a few degrees above outside temperature.
The thing to remember is how radiant barrier foil works. Normally, The sun heats up your roof. Then, your roof radiates heat in all directions. The radiant energy that enters your attic will be absorbed by your insulation and then eventually the heat will be transferred to the living space. Since air conditioning is simply the removal of heat, the less heat coming in, the less money needed to remove it.
Just like the Open-Ridge Method, radiant barrier foil breaks this path of radiant energy and “bounces” or reflects it back towards the roof. It does NOT really matter if the foil is 6 inches or 10 feet away from the roof, the foil will reflect the heat. The FlatTop method has all the benefits of the Open-Ridge Method but eliminates the need for ladders, or scaffolding in the attic.
How To Install:
Most of the install process is like the Open-Ridge Radiant Barrier Method with a few changes. With the FlatTop Method, it is best to start at the TOP and work Down.
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FlatTop Method uses a grid or straps to support foil |
Notice Metal Strapping To Support Foil and Create Flat Part |
The first step is to create some form of grid or false ceiling to support the foil in the flat area. Remember the foil is not that heavy. It is about 5 ounces per 100 square ft. This is about the weight of a heavyweight blue painters tarp. You can use just about anything to support the weight of the foil: wood, wire, warehouse strapping, duct strapping, bungee cords, etc. foil.
How High? – The best height is usually about 7 feet off the attic floor. For most attics this will be above the ductwork and allow you to reach the foil without using any ladders. Many customers who have very tall attics will use a step ladder and take it up to about 8-10 feet to provide extra storage space.
Also, take a look and measure the distance down the slope to the soffits. Depending on the steepness of the roof, 3 rows of foil might fit perfectly (12 ft). You can adjust the height of the FlatTop to meet the top of the foil on the slope. This can save materials and having to cut the foil.
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Metal and Nylon Duct Strapping |
Area Above Grid Forms Triangle Pocket in Top Of Attic |
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This shows how good attic ventilation is maintained. Air will flow from the soffits, behind the foil and out the exhust vents. |
Notice the Triangular Pocket formed above the Flat-Top part. Heated air will "Pool" in this pocket and find it's way out of your top exhust vents. |
How to make the grid. The easiest way is to purchase some metal duct strapping (with or without holes are OK) from your home improvement store or you can get it from and air conditioning supply company. It is thin metal and cuts easily and can easily be screwed into the roof rafters. Other grid materials can be: Nylon Duct Strapping, Wire, Wood, or Rope. Just about anything that can be pulled across the attic and fastened to the rafters will work. UPDATE: Lately many contractors have been using heavy-duty strapping material used to wrap boxes and crates. You can get it at www.uline.com
How Far Apart Should The Straps Be? – It really does not matter. The closer the grid you have, the less “Drooping” of the foil between them. Probably the “Ideal” distance would be about 7-10 feet between straps.
Odd Shaped Attics – Think Spider Web. It does not have to be perfect or pretty. You can even crisscross straps if needed. You just want SOMETHING to hold up the foil. Just try to get all the strapping fairly level so your foil will end up level.
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Illustration Of Metal Straps Screwed Into Rafter Bottoms |
A Cordless Screwdriver With a Hex Nut Driver Works Well |
Start Running Straps – Just Do It. Attach one end of the strap to the rafter bottom and pull across the attic and attach to the other side. Try to keep it level. As I mentioned, the metal straps work best, but other materials will do.
TIP: Use 1⁄4” hex head screws about 1 1⁄2 inch long and a magnetic nut driver with a cordless screw gun. This way you can use one hand to hold the strap and one hand to hold the screwgun without the screw falling out.
Use one screw to hold the strap and a couple more to “tighten” it in. One metal strap can easily span up to 20-40 ft. Figure out a pattern to run the foil on top of the grid and start running pieces across the TOP of the strapping.
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Foil Is Pulled On TOP Of The Support Straps |
Foil Tape Holds Foil To Metal Duct Straps |
TIP: Use FOIL AIR CONDITIONING TAPE to secure the foil to the FIRST strap. Run the foil all the way across the grid and let it hang loosely. Then have your helper pull the far end of the foil tight. Go back to the SECOND strap and tape foil to strap. Keep tension on the foil and tape to all straps until you reach your helper. This method will keep the foil straight, tight and neat.
Patch It Together – Install other pieces on the flat top and overlap a couple of inches until the flat part is done. You DO NOT need to tape the seams unless you want to make it look cleaner.
Should I Cut Holes In Top Flat Part? - It is probably a good idea especially If you have a whole house fan. Or, if you have an upper and lower attic and air flows into the upper part. You should cut a few holes about 12” x 12” to allow air for good ventilation. If your bathrooms fans vent into the attic (bad idea) you should also cut some holes to allow moisture to travel out of the attic. If you live in a cold climate, you should definitely cut several holes in the top AND cut a slit in the foil around the lower part of the roof. You want GOOD attic ventilation to keep moisture from the home condensating on the cold foil.