Spray foam the iso board would be a lot cheaper especially if this is a diy project.
Foam board roof vent.
Some people nail flat 2x4s on top of their existing roof and build a new roof to create a vent space but it would be hard to justify the cost for a workshop.
In a vented roof foam can seal the openings and serve as an air barrier and a vapor retarder in addition to its insulating function.
Intended for a roof pitch of 6 12 and higher it is recommended to use the cv3 vent for a roof pitch of 5 12 and lower installed without cutting or altering the roof structure made with fiberglass screen making it a mold and mildew free permanent solution to your ventilation needs while providing over 7 sq.
Attach the tongue and groove insulation boards to the concrete wall with adhesive.
Use a premade kit for this type of project.
All insulation materials require proper venting.
Cathedral roofs especially need a lot more insulation between the ceiling and the rafters because there usually isn t.
For new construction use rigid boards to insulate slabs and the outside of foundation walls.
Just peel the backing as you install.
The plyco quick vent is non wicking highly pliable while still providing a superior airflow.
In an un vented roof foam can serve as the air barrier and vapor retarder and prevent moisture from getting in to the roof.
Simply peel the backing and install.
Today there are more options.
Of airflow per linear ft.
Rigid foam and spray foam are two of them.
The superior adhesive helps make a complete seal.
Vent a foam insulated roof there used to be a time when the only insulation available was pink fiberglass.
For a basement remodeling project consider insulating basement walls with foam board.
If you want to install rigid foam above your roof sheathing in climate zone 3 then 1 2 inch of rigid foam board is not ideal this rigid foam layer needs a minimum r value of r 5 and that s impossible with 1 2 inch of foam.
Additionally raft r mate attic vent has an optional bend down air stop or insulation block at the top plate of the wall in one easy to install product.
As for iso board vs.
We used 25mm on the roof of our sprinter van conversion and 40mm thick board in the walls.
Plyco quick vent comes in 2 x 10 lengths for quick and easy installation.
Foam board insulation with rigid panels polystyrene and styrofoam boards are low cost and quick and easy to fit to the large panel in the camper van.
Owens corning raft r mate attic vent is an extruded polystyrene foam vent designed to assure unrestricted airflow from the soffit to the ridge vent.