Minimum Insulation On A Flat Roof

For a 1 inch board equivalent of 6 r value.

Minimum insulation on a flat roof.

A lower u value indicates better insulation properties hence u value requirements usually specify a maximum value. It is top quality and the most cost effective product for your flat roof. Cold roofs have the waterproof layer placed directly onto the roof deck and the insulation inside the roof just above the ceiling. We recommend having at least 20 r value worth of material for optimal energy efficiency.

Let me just mention that the flat roof as a motif certainly predates 1933. 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. 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. Cold roofs and warm roofs.

While expensive the best insulation is polyiso rigid foam. You can expect to pay about 55 100 sq ft. The typical u value of an existing uninsulated flat roof is 1 5w m2k. Minimum insulation r value requirements non residential above roof deck.

With a flat roof this issue does not arise but the u value constraint and the amount of insulation needed is just the same. When building a flat roof it is vital that a degree of falls is built into the construction to ensure rainwater run off. If you are upgrading the roof to meet current thermal requirements then the thickness of insulation will vary depending on its thermal conductivity. 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.

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. To achieve this add 100 to 160mm of insulation above the structural deck dependant upon insulant conductivity. Flat roof hello there s a lot of good material in this post for comment.

The target should be to achieve a u value of 0 25w m2k or better. Gropius and le corbusier in the 20s sought to capture the machine age by using industrial style roofs. 120mm of kingspan tr26 or similar will make the.