Roof Design Ventilation

Attics or roofs can be designed and constructed to be either vented or unvented in any hygro thermal zone map 1.

Roof design ventilation.

An important part of a healthy home and a complete roofing system is roof vents. For all roof designs however the most important feature of a roof ventilation system is adequate and balanced airflow. In short an adequate and balanced ventilation system is one that allows an equal amount of air to enter and exit the attic area. Vent roofs with steeples towers or cupolas can be found in different buildings from barns to cathedrals.

Advantages of proper roofing ventilation. Roof ventilation in a cold climate vents moisture and ensures a cold roof temperature to avoid ice dams. The building codes and building science for natural roof ventilation however only appeared in the 1940s. Roofs can be designed and constructed to be either vented or unvented in any hygro thermal zone.

The installation of roof vents is a crucial part of roof design because it allows for proper attic ventilation which may help prevent condensation and early aging of your roofing materials. The choice of venting or not venting is a design and construction choice not a requirement determined by the physics or by the building code. In cold climates the primary purpose of attic ventilation is to maintain a cold roof temperature to avoid ice dams created by melting snow and to vent moisture that moves from the conditioned space to the attic. Cool air in hot air out attic ventilation works on the principle that heated air naturally rises primarily utilizing two types of vents.

The model building codes allow both vented and unvented roof assemblies. Roof system ventilation is required by the model building codes such as international residential code irc which includes irc r806 roof ventilation that requires ventilation for attics and cathedral ceilings and icc r905 1 requirements for roof coverings that requires builders to follow the manufacturer s installation instruction. Let owens corning roofing help you calculate exactly how much ventilation you will need for a healthy and balanced attic with our 4 step ventilation calculator. As a homeowner it is important that you review the soffit areas of the home for soffit vents.

An important part of installing any system of ventilation into your roof system is to make sure that there is a point of entry and a point of exit for airflow. Intake vents located at the lowest part of the roof under. Enter square footage calculate or enter the square footage of the attic or area to be vented.