Unvented Attic With 12 12 Pitch

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.

Unvented attic with 12 12 pitch. 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. This heated air wants to rise vertically. 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. That s why an unvented roof assembly should never include interior.

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. 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. Tion air is obtained from an attic area it shall be in accor dance with chapter 7 of the international mechanical code. 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.

As they are all 3 12 or 4 12 pitch but the challenge to venting them still remains. If the pitch of the roof is above about 2 12 most of the shingle cooling is from exterior air convection. The air in the attic is warmed by the heat moving upward from the occupied part of the home. The same principle occurs in an attic.

Thank you again alan. 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. Maybe what i m referring to isn t truly a low slope roof. One year ago the roof with a 12 12 pitch was replaced.

1203 3 unvented attic and unvented enclosed rafter assemblies.