How To Insulate A 4 12 Pitch Attic

Lay the batts across the ceiling joists covering the existing insulation.

How to insulate a 4 12 pitch attic.

Per the scope of work i am wondering how to best install the insulation necessary in the very confined scissor truss attic space and still get the correct attic ventilation so we don t have condensation issues or future issues with the trusses due to insufficient attic ventilation. Either batting or blown insulation works in attics. This roof is even lower 4 12 at most and i m concerned it would be too difficult to fasten such a baffle where the rafter meets the top plate. I plan on removing the cedar shingles and any damaged sheet material underneath.

I will re insulate all cavities and then replace the sheet material. Batting comes in rolls and is sized to fit between rafters or joists. A roof s pitch is determined by how much it rises vertically for every foot it runs horizontally. I have used 1 4 inch plywood for insulation baffles in the past.

I will apply a waterproof membrane to seal it all. Insulating a sloping roof. I have a 4 12 pitch cathedral ceiling roof that seems to have little insulating value ice dam build up in winter. A 12 in 12 pitch is a steep 45 degree angle roof.

See the image below for more explanation on rise run and pitch. It s worth insulating the sloping insides of a pitched roof in order to conserve heat if the space is to be used for anything except simple storage. It must be remembered that just because a roof space is insulated and the floor boarded it does not mean that the room can be considered a habitable room for a full. Have thought of using 1 4 inch plywood and just fastening it at the top of say a 2 x 8 piece installed horizontally.

While wearing dust mask and gloves carry r 38 batts of unfaced fiberglass insulation into the attic. Water is insulation s enemy. Attic insulation using fiberglass mary has a four bedroom detached house 150m2 in size. Thus a moderate 6 in 12 roof pitch means that the roof rises 6 inches vertically for every 12 horizontal inches it runs.

Mary previously had 100mm of fibreglass insulation in her attic but decided to upgrade the insulation in her attic to the required 300mm following consultation with the seai and various contractors. Box out light fixtures. Look for water stains on the roof sheathing or damp or moldy spots on attic joists and existing insulation as a clue to where leaks might be. When unrolled batting assumes its loft or thickness.

She has an annual heating bill of 1 600.