Insulate Hip Roof

The right way to insulate attics and cathedral ceilings with batts using certain t.

Insulate hip roof.

Hitting amazing levels of 0 13w m will need 300mm of mineral wool or 180mm of rigid foam. Do not use plastic sheeting in this case. At hot roof design problems. Why not consider a hot roof instead.

Place the plastic sheeting on top of the rolled insulation. If there is a floor you will need to remove it to properly insulate the roof rafters. The later is used in new construction as the interior board serves as an inner wall. It s essentially impossible to effectively vent hips.

If the plastic sheeting is in pieces overlap the pieces by 8 inches and staple it in place directly to the roof rafters and the wall. Cut and insert 1 or thicker high r foam insulation sheets r 8 per inch against the furring giving a 1 or greater air path between the insulation and the roof deck under the cathedral ceiling. This has the added advantage of bringing any ductwork in the attic into the building envelope and it s becoming an accepted practice. In a warm roof structure the insulation is placed above or above and between rafters in order to avoid heat loss and energy transfer.

Bare foam board one sided sheathing board or double sided which is also reference as structural insulated panels. That is insulate the bottom of the roof deck with closed cell foam. To get the most r value with the least thickness use batt insulation with higher r value per inch in combination with rigid foam insulation. Rigid foam board is just above the roof deck or an exterior insulation option.

The rafters are 2x8 s. Nail 1 furring along every rafter side against the roof deck. What is the best way to insulate and more importantly ventilate an addition with a hip roof and a very low pitch. Rigid foam sheeting has an r value ranging from r 5 to r 10 per inch of thickness.

The roof overall is 26 x8 and the max height where it meets up with the house is maybe 2 2 1 2 high. It typically has 3 variations. In the case of a cold roof structure the insulation is placed between or between and under the rafters or at ceiling joist level and the roof is ventilated by leaving a 50mm gap above the insulation which vents air to the outside.