Minimum Insulation Thickness For Flat Roof

Zone 6 requires an r 30 minimum which is 5 2 thick.

Minimum insulation thickness for flat roof.

Hunter panels roofing tech topic r105. With a flat roof this issue does not arise but the u value constraint and the amount of insulation needed is just the same. In this case ventilation is required and the roof can still become wet with condensation which may cause materials to decay. 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.

Our guides to building regulations in wales adl1a 2014 building regulations. This exception will allow the minimum thickness to be 4 2 at the low point or 5 2 4 away from the drain on a per foot tapered system. 120mm of kingspan tr26 or similar will make the. 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.

Cold deck the thickness of insulation required will vary depending on the material you decide to use and the manufacturer s specification. Cold roofs have the waterproof layer placed directly onto the roof deck and the insulation inside the roof just above the ceiling. 13 july 2017 kingspan insulation uk. 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.

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. However some in the industry would consider up to 15 o as their definition of a flat roof. A ventilation gap usually 50mm should be provided between the top of the insulation and underside of the roof covering to allow the air to flow across. There are two types of flat roof.

The definition of a flat roof according to bs 6229 is having a pitch less than 10 o to the horizontal. Cold roofs and warm roofs. A lower u value indicates better insulation properties hence u value requirements usually specify a maximum value. A u value of 0 55 w m k is used for cavity insulation and 0 30 w m k for internal or external wall insulation.

Minimum insulation r value requirements non residential above roof deck.