Commercial Attic Ventilation Requirements

The thermal resistance thickness of the rigid insulation is climate dependent and moisture load dependent.

Commercial attic ventilation requirements.

As an example in an attic that is 30 feet by 20 feet you would have 600 square feet of floor area. It s essential for reducing moisture and preventing excessive heat. The same goes for attic ventilation. 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.

Traditionally building codes have required attic ventilation. However in pursuit of attic ventilation some people choose to install attic power ventilators. For large volume attics such as where roof slopes are greater than 8 12 designers also should consider increasing. Ibc 1203 2 requires 1 150 th of the attic area to be ventilated but there is an exception that is commonly used instead.

These are significant challenges. 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. 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.

In theory these are excellent tools for circulating air in the attic and keeping the attic temperature low. 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. According to the fha federal housing administration us for every 300 square feet of attic floor area you should have at minimum one square foot ventilation. Hence you would need two square feet 600 300 of attic ventilation.

Cool air in hot air out attic ventilation works on the principle that heated air naturally rises primarily utilizing two types of vents.