It is denser than eps and provides more r value with a rating of 5 per inch of thickness.
Rigid foam insulation between rafters.
This foam board insulation is available with straight or tongue and groove edges to help limit air movement.
Add r 15 kraft faced insulation to the rest of the rafter space 3 5.
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.
2 snap a chalk line between the length measurements.
This foam board insulation is the rigid pink or blue panels that can be found at home centers in many different thicknesses.
But mold and mildew can still grow on the surface of rigid foam insulation.
Secure insulation boards between the rafters and seal board edges using one part canned foam.
Rigid foam insulation is better at mitigating mold than fiberglass insulation.
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.
Rigid polyisocyanurate pir foam insulation boards from celotex are among the most thermally efficient commonly available insulation materials on the market.
I think you re wasting your time ripping every piece of foam to fit between rafters that are different distances apart.
The difference is that mold and mildew cannot enter rigid foam.
Seal any gaps inside the rafter space and rigid board with can foam i e great stuff as per the directions 4.
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.
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.
With the 4 below the rafters you would then be r 26 below the rafters and r 52 between no.
Fiberglass insulation s many open cells allow entry to mold and mildew.
If you do not plan on finishing your attic then the installation process will be straightforward.
Use a chalk line or t square to mark where it needs to be cut.
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.
Foam boards treated with a borate compound prevent this problem.
Use screws or nails with 1 inch minimum washers or caps.
Measure the space between rafters and cut the board to fit.
Properly cut boards should friction fit between rafters without falling out.
How do you install rigid foam board.
Alternate fasteners may be used with the type and length as recommended by their.
Trim and install one layer of 1 rigid polyisocyanurate foam sheathing between each rafter under the vent baffle 3.
2 would be to create the baffle in the 1st place.
