Under Slate Roof Insulation

Slate and tile actually ventilate themselves to some degree.

Under slate roof insulation. Check the depth between your trusses and the slates then install the correct thickness of kingspan in the gaps allowing for a 25mm air gap between the kingspan and the slates. Slate is a wonderful forgiving roofing. The best way is to insulate the attic floor. The problem with insulating behind the roof will lie in the uniformity of the insulation and the air seal because of the interior moisture.

The underside of the roof sheathing will dry rapidly to the exterior through the slate due to ventilation drying and diffusion. If you create an air space under the roof sheathing boards as dana suggests there is no need to have any soffit vents or ridge vent. A well ventilated roof space is good this stops your timbers rotting. The conditioned space must be totally sealed off from the insulation or the spray foam must be tight.

It is not uncommon to find that bats use a roof space. You would first have to create a vent channel under the slates by installing 1x1 sticks at the top of each rafter bay followed by stiff material like rigid foam or plywood. Answered 14th jan 2013 like 2.