Foil Insulation R Value

What is the r value or r rating of radiant barrier foil insulation.

Foil insulation r value.

Just as the absorbency of a raincoat is unrelated to its ability to repel water the r value of rfoil does not fully measure its ability to insulate and redirect heat energy. Basically r values range from 1 5 to 7 and the higher the number is the more effective the insulation sheet is at increasing thermal efficiency and thereby insulating your home. This testing to designate an r value only applies to conductive heat flow not radiant heat flow. For example if you have a type of insulation that has an r value of r 5 per inch of thickness you will need a depth of 6 inches of this insulation installed in your attic to reach r 30 if you live in zones 2 or 3.

Heat flow down r 10 6 heat flow horizontal r 6 8 heat flow up r 5 3. An r value is a measure of an insulation product s resistance to thermal heat transfer. It s a measure of how long it takes a heat absorbing product to absorb 100 of its potential and begin to transfer that heat out the other side of the product. Working with home insulation boards insulation panels typically come in 4x8 foot sheets.

Worth mentioning to get the equivalent r value to what the manufactures claim on the packaging the installer has to use spacers under the insulation to keep the prescribed air gap between the ducts and the foil. The astm c236 1224 tests that determine a products r value yield the following results for rfoil reflective insulation. Most metallic bubble wraps are about an r 1. These r values are a sum meaning this should be the total r value once you add up the entire depth of insulation.

It provides about r 5 per inch. R value is a term to describe how quickly heat will pass through or be absorbed by a product. Smaller sizes are also available. Products with foil facing help the panels resist moisture vapor.

The foil facing also makes it very easy to seal with good quality foil faced tapes. The r value is in essence the measurement of an insulation sheet s ability to resist heat flow. Triple pane windows with low e surfaces perform better than a triple pane window without low e surfaces because of the reduction of radiation low emittance across the air spaces. Air inherently has an r per inch value of 5 6 and is an excellent insulator when radiation and convection are controlled.

Other materials may only have a fifty percent increase in r value when their thickness is doubled. As a foil faced polyisocyanurate foam insulation enerfoil tm s r value actually more than doubles when it is twice as thick as you can see from the chart above. The sheets themselves are not created equally. Polyiso is typically used with a foil facing and it has an r value of 7 0 to 8 0 per inch of thickness.