R Value For Flat Roof Insulation

For a 1 inch board equivalent of 6 r value.

R value for flat roof insulation.

We recommend having at least 20 r value worth of material for optimal energy efficiency. Know exactly how much you need with our project calculators. 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. 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 measures how well certain building insulation materials can resist heat. Existing 3 4 inches of insulation. Flat expanded polystryene eps roof insulation is suitable for use with all roofing membrane materials flat eps roof insulation is compatible with loose laid and attached single ply membranes conventional built up roofing or modified bitumen systems. To convert the r value of a specific thickness of a material to rsi divide the r value by 5 67826.

Rsi r value système international is the metric equivalent. You should of course see the manufacturer provided technical data sheet for the r value of specific products. Fm approved subject to the conditions of approval as a roof insulation when installed as shown in the current edition of the factory mutual research approvals guide. The average r value for some common roof materials include.

To convert rsi to r value multiply the rsi by 5 67826. Minimum insulation r value requirements non residential above roof deck. Add insulation to attic. Flat expanded polystryene eps roof insulation provides high long term r value of eps and labor saving face laminates.

While expensive the best insulation is polyiso rigid foam. Excellent lttr value compared to any other fm class 1 rated products of equivalent thickness. The higher the r value the greater the insulation performance. It is top quality and the most cost effective product for your flat roof.

R value of various materials. Recommended insulation levels for retrofitting existing wood framed buildings. For a very good introductory overview article on r value see r values over at the website of. When determining how much insulation you need don t guesstimate calculate.

Here s a handy r value table that covers most types of roof coverings building insulation and a few other materials. For example two inches of extruded polystyrene with an r value of 11 has an rsi of 1. R value is calculated by more than just the insulation. State applicable energy ashrae zone minimum r value state local ms mississippi ashrae 90 1 2010 2 r 20 3 r 20 state local mo missouri 2012 iecc 4 r 25 5 r 25 state only mt montana 2012 iecc 6 r 30.

R value is used in the united states.