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.
Whether or not a hot roof is a superior setup depends heavily upon climate homeowner needs and building plans.
You create a warm roof or a cold roof simply by applying the layers of the roof in a different order.
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.
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.
Hot roofs act as a thermal break and will prevent ice dams from forming on the roof during winter months.
On a flat roof this could be air in at.
The hot roof assembly is found almost exclusively in new construction.
Thus your unventilated roof is indeed a hot roof.
That is the deciding factor.
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.
So what kind of difference does this make.
Namely the insulation layers.
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.
A warm roof is much more straightforward to install and provides a superior thermal performance and is therefore more costly.