Hot Roof Vs Cold Roof

In a cold roof the insulation is applied between the rafters but in a warm roof the insulation is applied on top of the existing roof surface.

Hot roof vs cold roof.

That is the deciding factor. A cold roof is best when you re initially creating a flat roof and is cheaper than a warm roof but does provide an inferior thermal performance. A little q a on the subject i tapped sean from alabama green building solutions to help clear up a few lingering questions i had about hot roofs and cool roofs. Hot roofs act as a thermal break and will prevent ice dams from forming on the roof during winter months.

Thus your unventilated roof is indeed a hot roof. Cold roof construction requires that a suitable ventilated air space exists above the insulation layer within which the air is constantly mobile being replenished by fresh incoming air whilst the air resident within the void space is being expelled via a natural vent action at another point. On a flat roof this could be air in at. Namely the insulation layers.

So what kind of difference does this make. In hot roofs the insulation is typically installed close to the roof sheathing but the main characteristic is the space under the sheathing is closed to fresh air flow. In cold roofs the outside air is allowed to freely flow under the roof sheathing. In climates that remain cold for a sustained period unvented roofs can cause more harm than good.

A warm roof is much more straightforward to install and provides a superior thermal performance and is therefore more costly. The hot roof assembly is found almost exclusively in new construction.