Finished Attic Ventilation

Flip the reverse switch in wintertime and it will push warmer air down to keep you cozy.

Finished attic ventilation.

Hvac sizing is like goldilocks not too big and not too small but just right for the house you have. If you re finishing your attic insulating it to the proper r value can cause a dramatic loss of. In cold climates the primary purpose of attic or roof ventilation is to maintain a cold roof temperature to control ice dams created by melting snow and to vent moisture that moves from the conditioned space to the attic ventilation acts to bypass the vapour barrier created by most roof membranes. Once they are in place you can then place the batts or blankets or blow insulation right out to the very edge of the attic floor.

In other words the entire vent opening doesn t count as vented space. In mixed climates ventilation serves either role depending on the season. Insulate your finished attic properly choose your insulation. Intake vents located at the lowest part of the roof under the eaves allow cool air to enter the attic.

That said air resistance and interference such as vent grates reduces the area of true ventilation. Install air chutes before installing insulation. Since parts of a finished attic are usually very close to the roof insulation often blocks proper ventilation that is needed under a roof structure. If there are returns from the upper attic down to the hvac system check to make sure they are not closed off by a damper and that the hvac system is properly sized for the load as per manual j.

In a hot climate the primary purpose of ventilation is to expel solar heated hot air from the attic or roof to reduce the building s cooling load and to relieve the strain on air conditioning systems. Without properly ventilating the roof your finished space can be just as unpleasant as an unfinished attic. Most building codes require a ratio of 1 150 ventilation space to attic floor space. You can also contact your local municipality to check on building code in your area.

Attic ventilation works on the principle that heated air naturally rises primarily utilizing two types of vents. If you ve got headroom a fan will make a finished attic more comfortable in warmer months by giving you a cool breeze indoors. Ventilation of attic spaces is required by most building codes as well as by roofing material manufacturers and the national roofing contractors association nrca. Generally speaking you need a ratio of 1 300 where for every 300 square feet of ceiling space you need 1 square foot of attic ventilation.

Hot air exhaust vents located at the peak of the roof allow hot air to escape.