Fine Homebuilding Attic Ventilation

The baffles will create vent spaces and prevent windwash energy robbing convective short circuiting air moving through the insulation 1 1 4 in.

Fine homebuilding attic ventilation.

In a situation where mechanical systems or ductwork has to be in the attic space or when there are lots of penetrations in the ceiling below the attic it s best to bring the entire attic area inside the thermal envelope. This way it s not as big a deal if the ceiling leaks air or if the ducts are leaky and uninsulated. Of attic floor area with between 40 1 2 sq. Attic ventilation works on the principle that heated air naturally rises primarily utilizing two types of vents.

Of ventilation area 1 sq. As the warm air escapes through vents high on the roof cooler air enters the lower vents. 15 articles and videos from the fhb archive that will take you through every step of the roof venting process. If an attic measures 900 sq.

Ft and 50 1 5 sq. Vent the roof deck. Intake vents located at the lowest part of the roof under the eaves allow cool. Attic fans are intended to cool hot attics by drawing in cooler outside air from attic vents soffit and gable and pushing hot air to the outside.

It s one of the more confusing aspects of home building and. Codes require a net free ventilation area nfva of 1 sq. But building scientist joe lstiburek takes issue with that opting instead for more ventilation at the eaves say a 60 40 split with the eaves getting the greater proportion. Of vents for each 300 sq.

In mixed climates ventilation serves either role depending on the season. Ft code requires that there be a minimum of 3 sq. Slots notched in the top of the timberstrand blocks placed between the tji rafters lets air flow into the ventilation channels from the cor a vent s 400 vent strips installed between the soffit boards. If you ve got a roof over your latest building project chances are you ve also given some thought to roof venting.

For every 300 sq. In an attic the primary driving force is the buoyancy of warm air rising in the vault of the roof. Roofs need a driving force to move air in and out and intake and exhaust vent openings large enough to facilitate this movement. However if your attic has blocked soffit vents and is not well sealed from the rest of the house attic fans will suck cool conditioned air up out of the house and into the attic.

Ft of ventilation area at the ridge and the remainder at the soffits.