How To Insulate Hip Roof
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.
How to insulate hip roof. To install the air chutes staple them directly to the roof decking. Air chutes when combined with soffit vents and a ridge vent will help prevent problems with condensation and ice dams. This is a styrofoam shoot that you staple to the underside of the roof deck stopping the insulation from compressing against the underside of the roof and creating a 1 1 2 airspace for 4 to 8 long. I would recommend that you install them the full length from the lowest part of the attic to where there is an adequate air space existing.
I was going to make a ceiling and insulate on top of that but the top of the roof at its highest point will be only about 3 feet above the floor of the attic at the center of the garage. Make sure it is flush against the wood as even a 1 inch gap can cause a 20 percent heating loss. Allow insulation to overlap the top plate of the exterior wall and for additional protection install insulation across the tops of joists as well. For rolled insulation place it between roof rafters.
Then feed the rolled insulation under wires and pipe if either is present. With a warm roof the usual process is to split the insulation into two layers. Airspace from the soffit to the ridge by installing a continuous air chute in each rafter bay. If 180mm is to be installed then 100mm board might be introduced between the rafters there has to be a minimum 25mm air gap between the insulation and the underside of the tiles or slates with an 80mm board running across the rafters.
I have the walls done but i m rethinking how to do the ceiling. Place the plastic sheeting on top of the rolled insulation. In a warm roof structure the insulation is placed above or above and between rafters in order to avoid heat loss and energy transfer. Cut each run to the proper length.