Lstiburek Rules For Venting Roofs

Lstiburek s rules for venting roofs gba a nice video for those who like them.

Lstiburek rules for venting roofs.

Although he does not mention the 1 300 rule in that particular article he does talk about splitting venting 60 to soffit and 40 to ridge so the space stays at a higher pressure than the inside of the house. The code calls for a minimum of 1 in. The idea of roof vents existed for hundreds of years with natural vents employed in chinese buildings during the tang dynasty natural ventilation ducts in the buddhist monks caves and wind catchers incorporated in arabian architecture. In a cold climate the primary purpose of ventilation is to maintain a cold roof temperature to avoid ice dams created by melting snow and to vent any.

The building codes and building science for. Lstiburek s rules for venting roofs you need an airtight ceiling lots of air flow plenty of soffit vents and deep insulation at the attic perimeter. In a cold climate the primary purpose of ventilation is to maintain a cold roof temperature to avoid ice dams created by melting snow and to vent any moisture that moves from the conditioned living space to the attic. Understanding manual j occupant loads.

Lstiburek s guidelines differ in several respects from code requirements. The code calls for a minimum of 1 in. The minimum net free ventilating area shall be 1 150 of the area of the vented space. Of airspace between the top of the insulation and the back of the roof sheathing.

Florida solar energy center paper on attic ventilation danny parker go to page 24 for shingle temp discussion. The intent of roof venting varies depending on climate but it is the same if you re venting the entire attic or if you re venting only the roof deck. Attic and roof venting in the code nearly everyone in the building industry knows the 1 300 or the 1 150 vent ratio the code includes see irc 2015 r806 2 minimum vent area. He digs until he finds real answers.

In the gba article lstiburek s rules for venting roofs 07 24 2011 he notes the importance of having continuous soffit vent so the entire under side of the roof gets air flow. For best performance the airspace in the vent chute should be a minimum of 2 in. Integrating solar electric and solar thermal panels. Danny is a geek s geek.

There are a few counterintuitive things to know about attic. If you choose to vent the roof deck then be serious about it and really vent it. Unless you re bulk filling rafter bays between 2x10 or 2x8 rafters with closed cell spray foam this approach will likely require you to fur out the raf ters to accommodate additional insulation to achieve desired r values. By joe lstiburek july 24 2011.

Of airspace between the top of the insulation and the back of the roof sheathing.