Flat Roof Minimum U Value

U value has an inverse relationship to r value.

Flat roof minimum u value.

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. A lower u value indicates better insulation properties hence u value requirements usually specify a maximum value. Ground floor underfloor heating 0 15w m k. External walls cavity 0 55w m k external walls other not cavity 0 35w m k.

You may also see ug and uw values in some situations. Insulation for walls including cavity walls solid walls and timber or steel framed walls. Pitched roof sloping ceilings. 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.

Find your zone on the map and then use the chart to determine the level of insulation you need to properly insulate your attic walls floors and crawlspaces. A wall with the u value of 0 5 w m2 k will lose heat at half the rate of a wall with a u value of 0 6 w m2 k. Minimum 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. Ground floor no underfloor heating 0 45w m k.

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. Column b is for other extensions upgraded existing thermal elements non exempt conservatories and conversion of unheated. The below drawing shows the u value requirements set out for new properties in the building regulations for each element walls floors and roofs. Get a u value calculation from our free online u value calculator or our technical department.

These represent the energy efficiency of the glass pane itself and the window as a whole respectively. You should of course see the manufacturer provided technical data sheet for the r value of specific products. 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. U value of a flat roof.

The actual specification required for a compliant building and necessary building fabric u value targets may vary depending on the actual overall proposed specification and the outcome of the energy. Here s a handy r value table that covers most types of roof coverings building insulation and a few other materials. 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. R value of various materials.

Insulation for flat roofs pitched roofs and balconies and terraces. The map and chart show each region of the u s the subsequent zones and corresponding r values.