Increasing Roof Rafter Depth For Insulation

After a bit more destruction and dust it is time to look at how we increased the rafter depth in preparation for the insulation.

Increasing roof rafter depth for insulation. Install a timber stop batten across the rafters as shown in position c with the batten equalling the thickness of the quinn therm insulation. 3 5 inches r13. So we extended our rafters with some two by fours giving us the space to increase our ceiling insulation to r30. Use cleats the same length as the width of the.

How to increase rafters for insulation step 1. It works well to increase the r value and furring strips and then drywall can be applied. 12 inches r38. I want to insulate with 50mm celotex or similar then plasterbd skim over.

Lay quinn therm qr insulation boards above the rafters butted tightly against the stop batten and supported on both sides by the rafters. In any case you will not be able to use your present roofsystem. For instance if the roof has 2 by 6 rafters and. 9 inches r30.

Multiply the appropriate r value times. Rafters are 83mm deep x 63mm wide at 425mm centres. For future reference here is the cavity depth you need for some common insulation r values. Almost there with the old fo.

Attach 1 2 inch wood cleats to both sides of the existing rafter. Measure the depth of the existing insulation. For example if the existing joists are two by eights which are 7 5 inches deep you can add two by six boards which are 5 5 inches deep. Each inch of batt type insulation provides an r value of 3 1 to 3 5 and loose insulation provides 2 9 to 3 7.

Figure the rafter depth needed to provide the desired r value. You may want to consider applying a rigid polyisocyanurate insulation typically r7 to 8 per inch on the bottom of the rafters after installing baffles continuous from eave to peak and batt insulation between the rafters. This gives you a total joist height of 13 inches which.