The thermal transmittance or u value of the complete roof system is calculated in accordance with established international standards.
Flat roof u value 2013.
Where not exempt a conservatory heated or unheated should be built to the same maximum u values as any other new work as listed in columns b and c of the table in clause 6 2 9 with the exception that glazing and framing elements forming the walls or roof of a conservatory are unlimited in area and should have a maximum area weighted.
Thickness varies according to the manufacturer s specifications.
State applicable energy ashrae zone minimum r value state local ms mississippi ashrae 90 1 2010 2 r 20.
These are expressed as a u value which needs to be achieved.
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.
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.
U value of a flat roof.
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.
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.
R value state local al alabama 2015 alabama commercial energy code 2 r 25 3 r 25 state.
The tables below show the suggested u values in england wales and scotland.
Column b is for other extensions upgraded existing thermal elements non exempt conservatories and conversion of unheated.
The required u value will depend on the location of the project england scotland or wales type of building domestic or non domestic and the application floor wall or roof.
Insulation for walls including cavity walls solid walls and timber or steel framed walls.
Check our library of roof u value calculations.
State only ky kentucky 2013 kentucky building codes 4 r 25 state local la louisiana 2009 iecc 2 r 20 3 r 20.
Get a u value calculation from our free online u value calculator or our technical department.
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.
A lower u value indicates better insulation properties hence u value requirements usually specify a maximum value.
This is placed over the roof joists and a board normally external ply is laid on top.