Minimum Thickness Of Flat Roof Insulation

There are two main types.

Minimum thickness of flat roof insulation.

Spray foam insulation sprayed directly onto the roof deck and then coated with acrylic or urethane coating as well as a layer of crushed stones sand. If you are upgrading the roof to meet current thermal requirements then the thickness of insulation will vary depending on its thermal conductivity. 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. 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.

120mm of kingspan tr26 or similar will make the. Minimum insulation r value requirements non residential above roof deck. Roofing insulation is one of the most important and misunderstood building components. 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. Others would treat even steeper pitches as flat roofs. The minimum roof insulation thicknesses allowed by the iecc is 1 less than the 5 of insulation. Cold roofs have the waterproof layer placed directly onto the roof deck and the insulation inside the roof just above the ceiling.

Cold roofs and warm roofs. 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. There are many different types and installation methods out there along with a lot misinformation about which products offer the greatest energy savings. Cold deck the thickness of insulation required will vary depending on the material you decide to use and the manufacturer s specification.

Roof coatings manufactured for existing roofs and used to extend their service life by 10 15 years. Insulation can also help to limit condensation and contribute to acoustic insulation depending on the type of insulation used. 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. They are typically installed on top of single ply modified or low slope metal roofs.

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. When starting at 5 thick there is a lot of extra insulation added to obtain slope to drain if it is possible at all.