Insulating Hot Cold Flat Roof

A warm deck roof is where the insulation is placed on top of the rafters joists and the roof covering is then placed over the insulation.

Insulating hot cold flat roof.

Basically the term cold roof refers to a traditional roof or vented roof while hot roof refers to a roof that is not ventilated and which has foam insulation attached directly to the roof sheathing. Flat concrete roofs are generally not ventilated since the ceiling internally is generally a plaster and skim coat directly to the underside of the cold concrete. It is top quality and the most cost effective product for your flat roof. This means there is a vapour control layer in the ceiling and cross ventilation at the eaves or the top of the walls.

While expensive the best insulation is polyiso rigid foam. Warm roofs offer a superior thermal performance and therefore come with a higher cost. For cold flat roofs the vapour layer needs to be positioned underneath the insulation layer on top of the room below to create an effective barrier. You can expect to pay about 55 100 sq ft.

No ventilation is required for these types of roofs. Basically there are two options to choose from when insulating a flat roof. To produce a hot roof rigid insulation is fitted outside above the weatherproofing. The insulation material is placed between the supporting joists leaving a gap of 50 60mm between the roof and insulation.

Lots of traditional flat roofs are of the cold roof construction type. For a 1 inch board equivalent of 6 r value. This is then covered with a further weatherproofing layer. Cold roof systems are highly inadvisable as insulation from the inside will inevitably lead to the formation of condensation.

On a warm flat roof the layer is installed underneath the insulation to stop moisture interacting with it through rising thermal pressure lower down in the building. Cold flat roof insulation. Warm flat roof insulation. With a warm roof the insulation is installed on top of the existing surface rather than in between the rafters.

We recommend having at least 20 r value worth of material for optimal energy efficiency. This will enable the airflow to circulate freely. Installing a warm roof can be extremely straight forward and simple to do. Warm deck or warm roof refers to a situation where the deck of the roof which is usually made of wood is below the.

There are three types of insulation solution if you have a flat roof. Cold roof a very bad idea.