Rigid Insulation Above Roof Deck R Value

High r value unvented roof assemblies will require a proportionally larger amount of insulation above the roof deck for condensation control.

Rigid insulation above roof deck r value. R value of various materials. The higher the r value the greater the insulation performance. R panel is manufactured with a closed cell polyisocyanurate foam core bonded to fiberglass reinforced facers and designed for use over metal nailable and non nailable roof decks with a variety of membrane systems. I would use polyiso with a top layer of eps as recommended in your blog post on the topic.

I m considering a roof design that would place all the insulation above the roof deck with no insulation below. Depending on the type of insulation you choose and the desired r value you want for your facility you may need to build up a few layers of insulation. R value measures how well certain building insulation materials can resist heat. Notes on the r value k values of different forms of asbestos.

For example two inches of extruded polystyrene with an r value of 11 has an rsi of 1. To convert rsi to r value multiply the rsi by 5 67826. Rosato asbestos insulation is the most authoritative source on asbestos properties and gives data for the thermal conductivity of asbestos in different forms and with varying temperatures for magnesia asbestos insulation at mean temperatures ranging from 100 f to 400 f the k value thermal. R value is used in the united states.

Johns manville r panel rigid roof insulation board offers r values of up to r 23 6 providing high thermal efficiency. Table r806 5 in the 2012 irc r806 4 in the 2009 irc indicates the amount of insulation above the roof deck required for condensation control assuming minimum required total insulation. Foamular xps roof insulation for commercial buildings page 5 foamular xps roof insulation for commercial buildings foamular xps insulation is a rigid foam insulation which meets the needs of today s design professionals for a truly sustainable insulation product. To convert the r value of a specific thickness of a material to rsi divide the r value by 5 67826.

The r value is a measurement of the heat loss and heat gain. After the roof deck is ready the rigid foam insulation is installed. The higher the r value means there is a higher ability to. With three layers of 11 2 in.

Here s a handy r value table that covers most types of roof coverings building insulation and a few other materials. Know exactly how much you need with our project calculators. For a very good introductory overview article on r value see r values over at the website of. Polyisocyanurate insulation above the sheathing and approximately 91 4 in.

Of cellulose insulation in the rafter cavities the roof shown here has an r value of approximately 63. Owens corning insulation products help improve thermal performance and control moisture in commercial institutional and. Deck for a thick roof rigid foam insulation installed above the roof assembly can create an energy smart roof. The project is in climate zone 4 seattle area and i want to have an open beam look in the ceiling.

You should of course see the manufacturer provided technical data sheet for the r value of specific products. Notes to the table above.