Finished Attic Ventilation

Hvac sizing is like goldilocks not too big and not too small but just right for the house you have.

Finished attic ventilation.

In other words the entire vent opening doesn t count as vented space. To effectively ventilate your roof create a 1 in. Insulate your finished attic properly choose your insulation. 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.

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. Most building codes require a ratio of 1 150 ventilation space to attic floor space. Flip the reverse switch in wintertime and it will push warmer air down to keep you cozy. That said air resistance and interference such as vent grates reduces the area of true ventilation.

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. In mixed climates ventilation serves either role depending on the season. Attic ventilation works on the principle that heated air naturally rises primarily utilizing two types of vents.

You can also contact your local municipality to check on building code in your area. Without properly insulating your finished attic room will also be cold in the winter. 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. 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.

If you re finishing your attic insulating it to the proper r value can cause a dramatic loss of. 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. 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. Intake vents located at the lowest part of the roof under the eaves allow cool air to enter the attic.

Rafter vents should be placed in your attic ceiling in between the rafters at the point where your attic ceiling meets your attic floor.