Install a Radiant Barrier in the Attic:
Foil and Paint Provide a Thermal Shield
© 2008-2009 by Kelly Smith all rights reserved
There are many ways to increase energy efficiency and
lower power bills.
Those two concepts go hand in hand and they are more important than ever; radiant barrier foil and
attic insulation address them both.
The Importance of Conserving Energy Now
We stand on the threshold of great change. The promise of alternative energy has yet to materialize
although it shows promise. Conventional solar panels are not workable on a large scale, but the
recent introduction of the new
thin film photovoltaic
technology is changing that.
The are two problems with fossil fuels. First, on the domestic front, politicians stand in the way
of production. Secondly, the petroleum that is produced abroad puts us at the mercy of petro-tyrants.
All homeowners can do at this point to protect themselves is be proactive with
green home building
on new construction, or some sustainable retrofitting on existing homes. The attic is a great place to
start.
Radiant Barrier Foil or Paint?
This is the question. I’ve done both on my home (see the photo above). Foil proponents say that paint
is not a “real” thermal shield, which sounds a bit like whining. The problem with paint is two-fold: the
effectiveness varies wildly by manufacturer and some installers (sprayers) thin it out too much to
boost profit.
With foil, on the other hand, you know what you’re getting. The effectiveness is rated by a property
called the emissivity (also called the emittance). The lower the number, the better.
There are many manufacturers. I used the Energy Q brand. It’s the one NASA wraps their
space-bound gadgets with.
Part of the economic stimulus package increases the tax credit for insulating material. Foil
falls in this category. Note, however, that the credit only applies to the material, not labor
installation costs. This makes it a sensible DIY project.
Methods for Installing Radiant Barrier Foil
There are three common methods of installation:
- Stapling it directly to the rafters.
- Stapling it in the space between the rafters.
- Laying it on the attic floor. Yhe foil has to be the right type for this method. Energy Q is
one brand that works well. This is the most effective way to keep the heat in the home
in the winter months. It’s also the best way to keep cool in summer. Jim Dutton of the Texas
Home Improvement show (AM 740 in Houston) explains it best. The attic is going to get hot anyway.
The important thing is the keeping it out of the living area.
In my case, I followed the third choice. My attic has little headroom to begin with, and the
wood framing
for the vaulted ceiling makes maneuvering even more difficult. If the attic is being used as a living space,
choice number one or two should be followed.
Tool List for Installation
These are the basic tools:
- Utility knife.
- Two tape measures, one to leave stretched out on the driveway for measuring, the
other to take measurements in the attic. You can use one, but two is more convenient.
It’s a real head-slapper for the installer to get ready to take more measurements
in the attic just to discover he’s left it downstairs on the driveway. Believe it.
- One or more rolls of metallic duct tape, not the cheap kind.
- A roll of masking tape.
- A can of bright-colored spray paint to mark places where it is safe to walk.
- 1” X 6” board, 5’ or 6’ long.
- Knee pads.
 A long stick with a nail on the end for pushing the foil into tight corners. Due to
the way my attic space is, I used a litter-gathering stick and taped it to the end of a
telescoping paint roller handle.
Cutting and Rolling Out the Foil
The trick here is planning and procedure. The game plan should be to work from the small corners
and end up at the attic entrance point.
- Measure and cut only as many pieces as is reasonable. Make it easy, the pieces don’t all have
to be aligned in the same direction. The edges just need to be overlapped by 3” or 4”.
- Cut the radiant barrier foil on the driveway.
- Stretch out and lock the tape measure blade along the length of the driveway.
- Set the 1” X 6” board perpendicular to the tape measure at the number appropriate for
the length of the sheet.
- Place the roll at the end of the tape measure blade.
- Unroll the foil up to and over the board. If the sun is bright, wearing a pair of polarized
sunglasses wouldn’t be a bad idea; the reflection off the foil can be intense.
- Cut the foil on the board using the utility knife.
- Starting at the end away from the roll, carefully roll up the sheet and secure it with
a bit of masking tape. Don't roll it too tight or too loose. The center of the roll should be
about 2 1/2” wide.
- Unroll the sheets in the attic and put them in place. Use the nail-stick for both unrolling
and fine-tuning the placement.
- Don't cover up soffit vents; this will impede air flow through the ridge vents.
- It may be necessary to cut the foil for framing. Cut a slit in the sheet and a double
“T” where the framing passes through it. Seal the slit with metallic duct tape.
Spraying the Radiant Barrier Paint
The paint can be purchased pre-mixed or as a powder to be mixed with white latex paint. If the
powder is used, it’s important to wear a respirator when mixing!
A compressor-driven or an airless spray rig may be used. Just be sure to use the proper tip. The
active ingredient is generally microscopic porcelain beads and aluminum flakes and they need room
to get out.
Wear a respirator and goggles when spraying the underside of the roof sheathing.
Other Energy-Conserving Tasks
There are a few other things to do as the installation progresses. Check the ductwork from the plenum to
the registers. Replace or repair as needed.
It only makes sense to add insulation while installing the foil. Insulation is also eligible
for the energy tax credit. But once again, just for the price of the material. Save all receipts for when
the time comes to file federal tax returns.
Recently Recommended Related Articles:
|
