Green Roof Assembly R Value

Every construction design architect engineer a e knows a material s r value is an important factor when specifying insulation products with many regulations requiring minimum values for wall ceiling and roof assemblies.

Green roof assembly r value.

What r value do i need. Determining insulation r value accuracy. Insulation thermal resistant r value requirements for the building should be integral to the roof membrane assembly below the vegetated roof components. Replacing the impervious surface of a conventional roof with.

The amount shown is an average amount used for roof system r value calculations. Unlike conventional earth covered structures garden roof assemblies are lightweight and can be installed on a wide variety of new and existing structures. In an uninsulated house more heat is lost through the ceiling and roof than any other part of the house making the roof the top priority for insulation. You should of course see the manufacturer provided technical data sheet for the r value of specific products.

For instance if you have a material with an r value of 12 attached to another material with an r value of 3 then both materials combined have an r value of 15. Depending on where you live and the part of your home you re insulating walls crawlspace attic etc you ll need a different r value. Adversely u value measures the rate of heat transfer. You can find some of the examples here.

However a green roof does not provide additional insulation. For a very good introductory overview article on r value see r values over at the website of. Completely dry growing media the dirt of the green roof so to speak has a minimal r value typically about 0 5 inch. Pitched timber framed roof r 3 3.

Knowing what r value and u values mean is key to following energy codes and to selecting products that best suit the climate zone you are building in. Extruded expanded polystyrene insulation is commonly used in inverted roof membrane assemblies irma. Typical recommendations for exterior walls are r 13 to r 23 while r 30 r 38 and r 49 are common for ceilings and attic spaces. R value of various materials.

As we said before the r value measures the thermal resistance of a material. Plants need water to grow so the green roof is designed to retain some degree of moisture. R value is essentially a product s resistance to heat flow which means that the higher the product s r value the better it is at insulating the home and improving energy efficiency. Sprayed polyurethane foam spf will have an r value of 7 14 when it is newly installed.

Here s a handy r value table that covers most types of roof coverings building insulation and a few other materials.