Old House Attic Ventilation

Attic ventilation adequate natural ventilation is important in the attics of homes.

Old house attic ventilation.

It may seem incongruous to allow cold air into your attic in the middle of winter but attic venting is an important climatic control that protects your house from moisture rot and mold. For instance attic ventilation is used widely in cold climates to evacuate the warm moist air that escapes from the living space below. Snow melts and the water refreezes on the cold eaves creating ice dams. Thick ridges of ice on your eaves in winter are a sign of poor attic ventilation.

In the summer vents in the attic keep the house nice and cool. Because the simplest and cheapest way to insulate an attic is to add material to the floor. In other words the entire vent opening doesn t count as vented space. In the winter months you want to cover your attic vents if you can.

Attic ventilation works on the principle that heated air naturally rises primarily utilizing two types of vents. Attics that are already insulated will need more elbow grease. Warm air that escapes rooms below gets trapped in the attic. The fan is typically mounted behind a gable end vent but other types are available that exhaust hot air through a roof vent.

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. Touch your ceiling on a warm sunny day. Warm air can also leave through your attic ventilation. If there s blown in insulation like ours rake back the fluffy stuff with a 3 or 4 ft long 1 x 6 photo 6 or use a garden rake or hoe.

Intake vents located at the lowest part of the roof under the eaves allow cool. If this air lingers it can condense on the underside of the roof sheathing and rot it. If a vaporretarder is not present in the ceiling to slow migration of moisture from thehome s interior into the attic attics require 1 square foot of free vent areafor each 150 square feet of attic area. But if the floor is covered in plywood you can t stuff enough insulation beneath it to do the job sufficiently not even in warm climates.

A hot ceiling tells you that the attic is acting like a solar oven raising your cooling bills and cooking the shingles. That said air resistance and interference such as vent grates reduces the area of true ventilation. If the attic is insulated with fiberglass batts just pull back any that are blocking the flow of air. Nowhere is this more common than in the attic.