Flat Roof Insulation Requirement

Insulation can also help to limit condensation and contribute to acoustic insulation depending on the type of insulation used.

Flat roof insulation requirement.

Another major performance issue with insulation and energy savings is its air sealing capability. What is flat roofing insulation. A common differentiating criteria between different types of insulation is the amount of r value they provide when correctly installed. There are two types of flat roof.

However in many situations the insulation may need to be primarily or entirely below the flat roof membrane and between the roof joists if so what are the best options. Laying flat roof insulation. R value is a measure of insulation s ability to resist heat traveling through it. Insulation for flat roofing is used to make a structure more energy efficient and minimise heat loss.

See the department of energy s doe ranges for recommended levels of insulation below. Minimum insulation r value requirements non residential above roof deck. Unvented flat roofs a technical discussion flat roofs have often been built with the insulation all on top of the vapor closed drainage plane as this avoids dew point condensation issues inboard of the roofing. The table below shows what levels of insulation are cost effective for different climates and locations in the home.

In this case ventilation is required and the roof can still become wet with condensation which may cause materials to decay. The higher the r value the better the insulation. 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. 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.

Cold roofs and warm roofs. With a flat roof this issue does not arise but the u value constraint and the amount of insulation needed is just the same. 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. Our guides to building regulations in wales adl1a 2014 building regulations.

Typical recommendations for exterior walls are r 13 to r 23 while r 30 r 38 and r 49 are common for ceilings and attic spaces. Insulation level are specified by r value. Cold roofs have the waterproof layer placed directly onto the roof deck and the insulation inside the roof just above the ceiling. Wales new dwellings.

There are many options available to fulfil this requirement as you will find out below.