Minimum Insulation Thickness For Flat Roof

The definition of a flat roof according to bs 6229 is having a pitch less than 10 o to the horizontal however some in the industry would consider up to 15 o as their definition of a flat roof.

Minimum insulation thickness for flat roof.

However if we do not include removal of old roofing you are looking at about 7 50 to 9 00 per foot of roofing plus about 2 50 to 3 00 per foot of 5 thick insulation say about 10 12 per square foot. Cold roofs have the waterproof layer placed directly onto the roof deck and the insulation inside the roof just above the ceiling. With a flat roof this issue does not arise but the u value constraint and the amount of insulation needed is just the same. Flat roof insulation thickness.

See the department of energy s doe ranges for recommended levels of insulation below. When building a flat roof it is vital that a degree of falls is built into the construction to ensure rainwater run off. Others would treat even steeper pitches as flat roofs. A lower u value indicates better insulation properties hence u value requirements usually specify a maximum value.

Cold roofs and warm roofs. 120mm of kingspan tr26 or similar will make the. It should be of the maximum available thickness. The typical u value of an existing uninsulated flat roof is 1 5w m2k.

U value of a flat roof 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 chosen insulation laid on top of this should be able to take the weight of anything put above it on the roof without compression or protected from compression by further sheeting. Minimum insulation r value requirements non residential above roof deck. There are two types of flat roof.

In this case ventilation is required and the roof can still become wet with condensation which may cause materials to decay. 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. Achieving a u value of 0 20w m meaning your roof will be better insulated than your walls will need 120mm thickness of rigid foam or 200mm of mineral wool or natural insulation.