How does TechShield® compare to AtticFoil®? I get this question just about everyday.  First, what is Techshield®?  Techshield® is a roof decking material – usually OSB that has a sheet of aluminum foil laminated on one side. Techshield® is made by LP Building Products or Louisianna-Pacific Corporation and is probably the most popular brand of radiant barrier decking.  Other brands are Solarboard by Norbord and Thermostat by Georgia-Pacific.

Products like TechShield must have the foil side facing toward an open air gap, like an attic space.

The main difference between Techshield® and AtticFoil® is that Techshield® is used almost exclusively for new construction or whenever a roof deck is being replaced.  AtticFoil® is most commonly used inside the attic of existing homes.

For most new construction projects, I recommend using TechShield® (or another brand).  The products work well, the cost of upgrading from regular OSB decking to radiant barrier decking is pretty minimal and there is NO additional labor cost since the Techshield® is installed just like a regular OSB roof deck.  The foil side MUST face the attic air space (foil facing DOWN).  If you install the foil facing up and then put roofing felt and shingles on top, you will get NO benefit.

Do they work the same?  Yes and No.  Techshield® works off a quality called EMISSIVITY.  Basically, this is the ability to NOT convert energy to radiant heat. The roof deck will get hot and would normally want to emit radiant heat both upward and downward.  By putting the foil on the bottom of the roof deck, it greatly reduces the ability of the deck to radiant heat downward.  This is similar to taking two HOT baked potatoes and wrapping ONE with foil.  The potato with foil will stay hot longer since the foil will reduce or slow down the amount of energy (heat) emitted.

If you were to wrap only half the hot potato with foil, then you have something similar to TechShield®.  In this case, the potato would emit more heat upward through the area without foil compared to the side with foil.  By reducing the heat emitted into the attic, this causes the attic contents (wood, insulation, framing) to be cooler.  Combined with adequate attic ventilation the attic air temperature will also be significantly cooler.

AtticFoil Radiant Barrier draped under a new roof deck.

AtticFoil® works off the quality of REFLECTIVITY since there is an airspace between the source of heat (the roof deck) and the foil.  The radiant heat is STILL emitted by the roof deck, but hits the foil and is reflected back keeping everything below the foil cooler since the items never get a chance to absorb the radiant heat coming off the roof.

Don’t worry about overheating the roof deck – it will only increase between 2º-10º degrees.

By stapling to the bottom of the rafters, you will usually achieve a greater reduction in overall BTU’s coming into the attic compared to radaint barrier decking.

Can I make my own radiant barrier decking like TechShield using AtticFoil®? You can and it is VERY easy!  Simply roll AtticFoil® Radiant Barrier foil out on standard 4’x8’ sheets of OSB or plywood. Then use a hammer staple and ¼” staples to tack it down.  When installed over the rafters it will jut like a piece of radiant barrier decking.  Or, if you want to install a radiant barrier for new construction, you can run the foil across the rafters and let it “droop” down about 4-5” between the rafters.  By doing this method, the AtticFoil® will work off the reflectivity quality compared to the emissivity quality of foil.  Be sure to leave a gap at the top and bottom of each rafter run for air to find its way up and out of the attic.

8 Comments to “Techshield Compared To AtticFoil® Radiant Barrier”

  1. Mike Dillard says:

    Very informative and exactly the verification that Iwas looking for. Our area in Dallas was recently hit by a hail storm and we have to install a new roof. I was looking to incorporate some form of radiant barrier since i have this opportunity. After reading your information it appears i have no opportunity to improve the situtation unless i have missed something or you have another suggestion.

    Thanks
    Mike

    • Ed Fritz says:

      Mike,

      You are correct in that you are pretty limited if you want to just scrap off the old shingles, and put new shingles down. You MUST create some type of an air space to force the heat to convert to it’s radiant form. Then, when the heat tries to cross the airspace, it can easily be reflected.

      Here are some options for doing this. You can Install Radiant Barrier Under a Metal or Tile Roof. Or, take a look at what I did with my home. I built a double-deck roof system and used traditional shingles, but the air space is between the two decks.

      All The Best!
      Ed

  2. Pilar says:

    Can I run the foil across the rafters and let it “droop” down about 4-5” between the rafters, then lay techfield roof deck on top.. would that work as well as the double deck system??

    • Ed Fritz says:

      Pilar,

      Combining a radiant barrier decking with the “drooped” method will definitely yield better results than the radiant barrier decking alone. I would not say it will perform the same as the double deck system since that system is installed over a foam-sealed non-vented attic. I used to not really recommend adding AtticFoil Radiant Barrier below Techshield since I did not think it would produce a substantially result. However, from personal experience with the double deck system and hearing from many customers who have installed in an attic under Techshield, I now think that if you can keep the cost down (A DIY installation) then it is worth it.

  3. jim says:

    Hi Ed
    I have a question about a metal roof. I was reading about air flow. I’m redoing a sun room that has a flat metal (tin) roof on it. I am planning on running 2 x 8’s and then installation inbetween the rafters and then OSB techshield on top. I will not have any air flow because it’s a flat roof. So I see you need air flow for it to work. My question is would it help for me to install the techshield with no air flow or would it make it hotter ? Also should you use techshield on outside walls ? I live in so. CA so it gets very very hot here in the summer. Thank You, Jim

    • Ed says:

      Jim,
      Just to clarify: it’s not air FLOW that is needed for the foil to work, it is an air GAP that is required (meaning the air can be a dead air space, and not flowing/moving). With no air gap, the heat will not be in radiant form so the Techshield will be useless as a radiant barrier. Take a look at this page for more info on why the air gap is needed for any radiant barrier to work: Why An Airspace is Required for Radiant Barrier.
      You can use radiant barrier in walls – again, you just have to create an air gap. This page details exactly how to do this: Installing Radiant Barrier in Exterior Walls.

  4. Kurt Shafer says:

    Ed,
    Great to see your pages and good to know the owner of AtticFoil. I bought 1000 SF of your 26 inch wide foil and put up about 500 SF in the attic of my 2800 SF 2 story. I posted a video of it when I measured the bottom of the east facing roof at 11 AM last July. It was 102 degrees. After your atticfoil went up the underside was 85 degrees, the temp of the air we were in.

    I am convinced that the roof heats the air and the air heats my ceiling and the ceiling heats my rooms. Do you know of any scientific study that corroborates my theory? I am sure that it almost does not matter how much insulation I have, the ceiling will heat up.

    • Ed says:

      Kurt,
      You are on the right track as far as the direction of the heat flow, but it’s not so much the hot AIR that is causing uncomfortable living spaces, it’s the heat traveling THROUGH the air (the radiant heat flow) that is getting absorbed into the insulation and, ultimately, the home. So it does in fact matter how much insulation you have because a small amount of radiant heat will pass the foil and it will travel until it is absorbed into the insulation. Having that insulation between the heat source and the living space slows down the conductive heat so the home doesn’t heat up as quickly. Otherwise, if it were all about air temps, then ventilation should be able to cool a home, but we know that ventilation alone does not in fact do that. A more in depth look at this can be found here: Radiant Heat vs. Conductive Heat

Leave a Reply

You can use these tags: <a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <strike> <strong>