Old House Attic Ventilation

Nowhere is this more common than in the attic.

Old house attic ventilation. For instance attic ventilation is used widely in cold climates to evacuate the warm moist air that escapes from the living space below. A hot ceiling tells you that the attic is acting like a solar oven raising your cooling bills and cooking the shingles. Touch your ceiling on a warm sunny day. Attic ventilation works on the principle that heated air naturally rises primarily utilizing two types of vents.

That said air resistance and interference such as vent grates reduces the area of true ventilation. If this air lingers it can condense on the underside of the roof sheathing and rot it. In other words the entire vent opening doesn t count as vented space. Attics that are already insulated will need more elbow grease.

The fan is typically mounted behind a gable end vent but other types are available that exhaust hot air through a roof vent. 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. Warm air can also leave through your attic ventilation.

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. Plan to pull up the flooring and layer new insulation on top of the old. 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. 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.

Attic ventilation adequate natural ventilation is important in the attics of homes. If the attic is insulated with fiberglass batts just pull back any that are blocking the flow of air. Thick ridges of ice on your eaves in winter are a sign of poor 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.

Air sealing and insulation. Unless an older house has undergone an energy upgrade it s certain to have too much air leakage and too little insulation. Warm air that escapes rooms below gets trapped in the attic. In the winter months you want to cover your attic vents if you can.