The Roof Sandwich

Hard foam insulation is added above the wood decking.
The first layer of hard foam forms the vapour barrier.

A total thickness of 7 inches of hard foam achieves
an insulation value of approximately R 34.

Hard foam insulation material.

This tape is used to seal the insulation panels
of the first layer together, creating the vapour barrier.

A layer of 1/2 inch plywood is added on top
of the insulation.

The next layer is this roofing membrane.

Installation of the roofing membrane.

This is how you do it.

The membrane makes the roof watertight.
The steel roof will follow on top of that.

View from the roof.

Work is going on under the tarp to install
the wood decking on the north side.

Interior view of the ceiling formed by the wood decking.

Kitchen ceiling

Posts and beams and ceiling.

Living room / dining room ceiling.