This foam board insulation is the rigid pink or blue panels that can be found at home centers in many different thicknesses.
Rigid foam insulation between rafters.
I would also like to attach 4 x8 sheets of rigid foam at least 1 2 inch thick to the lower edge of the rafters to prevent thermal bridging.
Rigid foam insulation is better at mitigating mold than fiberglass insulation.
2 would be to create the baffle in the 1st place.
Use screws or nails with 1 inch minimum washers or caps.
Secure insulation boards between the rafters and seal board edges using one part canned foam.
Fiberglass insulation s many open cells allow entry to mold and mildew.
Rigid polyisocyanurate pir foam insulation boards from celotex are among the most thermally efficient commonly available insulation materials on the market.
Seal any gaps inside the rafter space and rigid board with can foam i e great stuff as per the directions 4.
Foam boards treated with a borate compound prevent this problem.
Rigid foam insulation is considered to be impervious to water.
The rafters are 2 6 so there is 5 5 of depth under the roof deck to put layers of rigid foam into as a stack of pancakes between the rafters.
2 snap a chalk line between the length measurements.
How do you install rigid foam board.
But mold and mildew can still grow on the surface of rigid foam insulation.
It is denser than eps and provides more r value with a rating of 5 per inch of thickness.
With the 4 below the rafters you would then be r 26 below the rafters and r 52 between no.
Use a chalk line or t square to mark where it needs to be cut.
The difference is that mold and mildew cannot enter rigid foam.
Trim and install one layer of 1 rigid polyisocyanurate foam sheathing between each rafter under the vent baffle 3.
Measure the length and width between two rafters in your attic and transfer the measurements to a 4 ft by 8 ft of rigid foam insulation board.
Alternate fasteners may be used with the type and length as recommended by their.
Also you d have to stack a lot of pieces of foam on top of each other or add other insulation on top in order to get any real insulating value which would make the waste of time add up significantly.
But a 2x6 rafter with a 1 5 vent space would give you the ability to put 4 of rigid insulation r 26 in that space which was not filled.
Measure the space between rafters and cut the board to fit.
Depending on the specifics of the roof it may be possible to fully fill the rafter depth or in most cases leave a 25mm or 50mm air gap between the top face of the insulation and the sarking membrane.
This foam board insulation is available with straight or tongue and groove edges to help limit air movement.
Properly cut boards should friction fit between rafters without falling out.
Add r 15 kraft faced insulation to the rest of the rafter space 3 5.
