Insulation Over Existing Flat Roof

Gable end detail overhang cut and then rebuilt to hide the thickness of the over roofing rigid insulation.

Insulation over existing flat roof.

The target should be to achieve a u value of 0 25w m2k or better. Composite insulation works in flat and low sloped roofs with a variety of roof coverings. However we lose r value where the taper is thinnest and need to insulate under the sheeting. How to install insulation board over an existing roof membrane 1.

Calculate the total square footage of the roof to determine the number of. I like rock all because of its higher r value fire and moisture resistance and good cost per r value 6. We toyed with spray foam but this may be overkill as we would have to insulate areas that don t require it. Install roofing over a wind barrier like spun olefin.

We are insulating a flat roof with tapered rigid insulation over a moisture barrier and then capped with modified bitumen. The quest for greater energy efficiency in buildings has led to increasing interest and need for insulation improvements in hvac equipment more airtight construction new materials and assemblies. Insert the pry bar. This could be metal or roof sheathing and shingles.

To achieve this add 100 to 160mm of insulation above the structural deck dependant upon insulant conductivity. Senior engineer manager at icynene john broniek makes the case for the unvented attic assembly and why insulating the underside of the roof makes sense. How to insulate a flat roof warm flat roof. The 6 inches of rigid insulation added to the top of the existing roof deck needed to be done in a manner that was invisible.

Fill this space completely with insulation. The rigid foam can be installed over new sheathing coated with an integrated water resistive barrier as shown in figure 1 or the insulation can be installed over the existing roof sheathing which is first covered with a fully adhered air control membrane that extends up the parapet sides above the flat roof as shown in figure 2. Make a grid frame work of 2 dimensional to make space for the insulation. Remove all existing flashing material from around vents and pipes using a pry bar and hammer.

Measure the roof with a tape measure. Composite insulation reduces the need for a cover board when applying different membrane roof coverings. One of the main benefits you will receive from installing a warm flat roof is condensation will not.