Once you have these in place measure the length of the spaces between your rafters.
How to install insulation in roof rafters.
When installing rigid insulation in an attic to be finished as a living space you must provide a route by which hot air can escape.
Use your straightedge to compress the insulation before cutting and use a very sharp utility knife to assure a good straight cut across the fiberglass batt.
I would really like to get more than r 13 and the current installation is probably providing r 1 with all the missing pieces.
Install ventilation baffles into the space between the rafters before you install the insulation usually by stapling into place.
Apply insulation between rafters when finishing an attic into a heated room or when building a cathedral ceiling in the home.
How to install rafter insulation.
If you have a solid floor covering the roof rafters use the claw end of a hammer to pull the floor up in several locations and blow the insulation under the boards.
Garages built without attics are.
When you use solid insulation board to create a warm loft the key thing to remember is ventilation you must keep a 50mm gap between the roof and the rigid insulation board.
This requires the use of soffit vents and a roof ridge vent to.
They are directly below the roof sheathing and are were insulated with fiberglass batts stapled between the 2x4 rafters.
The baffles will allow circulation to continue even though insulation has been installed directly in the path of the rafter air movement.
Then blow another layer on top of the roof rafters.
Air circulates from the lower part of the roof overhang through the rafters.