Installing Radiant Barrier Over Flat Roofs

Using Radiant Barrier Outside on Flat Roofs & Concrete Buildings

Would laying AtticFoil™ directly on the roof of these buildings be effective in reducing the heat absorbed by the roof and radiating into the structure below?


Roof systems on commercial buildings (or flat roofed residences) are usually quite different from most residential roofs. They are usually flat, with metal or concrete components, versus standard wood. Because of this, commercial buildings and homes with flat roofs often have poor insulation and uncomfortable living/working spaces.


Although this is not a typical use for AtticFoil™, it would work great! It would be best to create a system that will keep the foil a couple of inches above the concrete (on the outside/exterior of the structure).


One way to do this would be to lay out some bricks or boards to create a raised platform, and then attach the foil to that platform.


We recommend taking the whole roll of foil and drilling a few 1/2″ holes all the way through into the core. This will create a “Swiss cheese” effect which will give more drainage holes and prevent pooling and sagging of the foil. This keeps the foil from coming into direct contact with the concrete, so it is up and away from the roof where water could collect. This is important to do because of two reasons. First, if you allow water to pool and collect on the foil’s surface, then over time this will cause the foil to get dirty and loose some of it’s effectiveness. Secondly, because of the pH of concrete, you do not want to have direct with the foil and the concrete since it can cause oxidation of the aluminum over time.


Overall it will work great and we have had customers do things like this on commercial buildings and residences/mobile homes with flat roofs. It’s not exactly the intended use of AtticFoil™, but from experience of testing and other customers, we would estimate you could get at 2-3 years (or more) of service from the radiant barrier.