Here s a handy r value table that covers most types of roof coverings building insulation and a few other materials.
Flat roof u value 2015.
For a very good introductory overview article on r value see r values over at the website of.
Reference table for u values u value is the coefficient of transmission i e the transmission of heat through the materials which compose the building s envelope or outer shell.
Check our library of roof u value calculations.
These can be supported with a detailed report.
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.
Column b is for other extensions upgraded existing thermal elements non exempt conservatories and conversion of unheated.
U value has an inverse relationship to r value.
Non residential above roof deck.
Epdm rubber roof covering 19mm ply 50mm ventilated air layer protect vp400 plus lr membrane sip at specified thickness protect vc foil ultra insulating a vcl 25mm service void 50mm gyproc thermaline super.
Flat epdm roof description.
0 25 column a is for extensions where the existing dwelling s walls and roof u values are worse than 0 70 w m k in the walls and worse than 0 25 w m k in the ceiling.
A lower u value indicates better insulation properties hence u value requirements usually specify a maximum value.
R value state local al alabama 2015 alabama commercial energy code 2 r 25 3 r 25 state local ak alaska 2012 alaska building energy efficiency standard 7 r 35 8 r 35 9 r 40.
Column b is for other extensions upgraded existing thermal elements non exempt conservatories and conversion of unheated.
R value of various materials.
For the majority of flat roofs built up in a series of material layers each of a consistent thickness and performance the most appropriate calculation type is the combined method detailed in bs en iso 6946.
For more information see our articles and how to videos below.
To comply with part l of the building regulations 2010 all roofs to rooms except those in unheated buildings should be thermally insulated to a maximum u value of of 0 18 w m k.
The easiest way of getting a u value calculation is by using our free online u value calculator.
The thermal transmittance or u value of the complete roof system is calculated in accordance with established international standards.
0 25 column a is for extensions where the existing dwelling s walls and roof u values are worse than 0 70 w m k in the walls and worse than 0 25 w m k in the ceiling.
For example a building with material with an r value of r 11 converts to an u value of 0 09 1 r or 1 11 0 09.
Here s my 2 cents and insulation guide for a cold flat roof concrete slab floor internal stud wall and to find out what type and thickness of insulation.
