Retrofit Insulation Flat Roof

Exterior roof insulation retrofit unvented roof covering the roof of an old house with a blanket of insulation makes the house more comfortable and it cuts energy use.

Retrofit insulation flat roof. In essence a steel framework is erected over the existing roof. Our insulation for existing flat roofs is ideal for extensions dormer roofs and includes a layer of either 25 50 75 or 100mm insulation board. Flat roof insulation by using our method of fitting insulation on the outside of the flat roof above the main decking boards but below the waterproofing layer we are able to protect the deck boards. The use of metal retrofit roofs allows the flat roofed buildings to undergo a transformation into a sloped roof building.

To produce a hot roof rigid insulation is fitted outside above the weatherproofing. Image courtesy of building science corporation. Hack n stack sealed foam board between the rafters would be better since it s at least an air impermeable insulation but even that would require a vent gap below the roof deck to meet code and you d still be under r38 on that 2x6 rafters unless you. These new roofs can be either low sloped less than 2 12 functional roofs or high pitched greater than 2 12 architectural roofs depending on the expectations of the building owner.

I d like to add insulation to this truss space. Custom designed retrofit systems are available such as star buildings nu roof system. Sheathing is removed from a flat roof to retrofit with air sealing insulation and water control layers. Batts between rafters in would require adding ventilation between the insulation roof deck.

This is then covered with a further weatherproofing layer. For larger roofs you may need to provide direct framing to framing contact. It needs to be furred out with something so the trim details will later match. The house has a flat epdm roof open chord roof trusses no ventilation and r 30 fiberglass batts with dubious installation quality wiring interrupts can lights swamp cooler ducts.

Cold roof a very bad idea. The concept can be applied to almost any flat roof and low slope or high slope configurations are possible. Remove two or three roof sheathing boards near the perimeter of the roof leaving one or two boards at the parapet figure below. It is ready to accept metal panels.

It makes a lot of sense if the rafter cavities are already insulated and it is most affordable when the roof needs replacement.