Unvented Attic With 12 12 Pitch

Unvented attics and unvented enclosed roof framing assemblies created by ceilings applied directly to the underside of the roof framing members rafters and the struc.

Unvented attic with 12 12 pitch.

The air in the attic is warmed by the heat moving upward from the occupied part of the home. The beam was rough cut cedar but turned black over time so it is now painted white several coats of stain block and finish paint several times water stains have appeared on the beam which was attributed to another roof leak. Low slope shed roofs that range in pitch from nearly flat to 4 over 12 are common in the southwest and in dense urban neighborhoods of the northeast. These roofs are either framed with deep trusses or framed with rafters that are separate from the ceiling joists.

As they are all 3 12 or 4 12 pitch but the challenge to venting them still remains. Senior engineer manager at icynene john broniek makes the case for the unvented attic assembly and why insulating the underside of the roof makes sense. One year ago the roof with a 12 12 pitch was replaced. Maybe what i m referring to isn t truly a low slope roof.

The quest for greater energy efficiency in buildings has led to increasing interest and need for insulation improvements in hvac equipment more airtight construction new materials and assemblies. This heated air wants to rise vertically. Thank you again alan. The same principle occurs in an attic.

In a non sip vented attic there s about r1 of roofdeck felt between the hot shingles and none too cool attic air whereas there s r0 1 0 25 of boundary air insulating it from the cooler exterior. If the pitch of the roof is above about 2 12 most of the shingle cooling is from exterior air convection. In a house with a regular or steep pitched roof the air hits the underside of the roof sheathing and redirects at an upward angle. This happens when the insulation of the snow on the roof is so thick that is traps the heat and overpowers the roof s insulation values causing melt at the roof surface.

1203 3 unvented attic and unvented enclosed rafter assemblies.