Commercial Attic Ventilation Requirements

The higher the interior moisture load the higher the thermal resistance required for the rigid.

Commercial attic ventilation requirements.

Exception 1 allows you to only ventilate 1 300 th of the attic area if 50 to 80 of the ventilation occurs at least 3 above eave or cornice vents. The same goes for attic ventilation. Intake vents located at the lowest part of the roof under. The thermal resistance thickness of the rigid insulation is climate dependent and moisture load dependent.

Cool air in hot air out attic ventilation works on the principle that heated air naturally rises primarily utilizing two types of vents. In theory these are excellent tools for circulating air in the attic and keeping the attic temperature low. Ibc 1203 2 requires 1 150 th of the attic area to be ventilated but there is an exception that is commonly used instead. The colder the climate the higher the thermal resistance required for the rigid insulation.

Measure the length and width of the attic floor space to be ventilated. The intended purpose was to allow warm air and moisture to escape. These are significant challenges. As an example in an attic that is 30 feet by 20 feet you would have 600 square feet of floor area.

For large volume attics such as where roof slopes are greater than 8 12 designers also should consider increasing. Regarding attic ventilation nrca recommends designers provide at least 1 square foot of nfva for every 150 square feet of attic space 1 150 ventilation ratio measured at the attic floor level ceiling. Hence you would need two square feet 600 300 of attic ventilation. However in pursuit of attic ventilation some people choose to install attic power ventilators.

Vented attics can be effective as long as hvac ducts are not located in them and the ceiling deck is well air sealed and insulated.