Old House Attic Ventilation

Air sealing and insulation.

Old house attic ventilation.

Warm air can also leave through your attic ventilation. In the winter months you want to cover your attic vents if you can. 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. Thick ridges of ice on your eaves in winter are a sign of poor attic ventilation.

Plan to pull up the flooring and layer new insulation on top of the old. Snow melts and the water refreezes on the cold eaves creating ice dams. If this air lingers it can condense on the underside of the roof sheathing and rot it. Warm air that escapes rooms below gets trapped in the attic.

If the attic is insulated with fiberglass batts just pull back any that are blocking the flow of air. Unless an older house has undergone an energy upgrade it s certain to have too much air leakage and too little insulation. In other words the entire vent opening doesn t count as vented space. 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.

For instance attic ventilation is used widely in cold climates to evacuate the warm moist air that escapes from the living space below. Intake vents located at the lowest part of the roof under the eaves allow cool. 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. Touch your ceiling on a warm sunny day.

In the summer vents in the attic keep the house nice and cool. A hot ceiling tells you that the attic is acting like a solar oven raising your cooling bills and cooking the shingles. Nowhere is this more common than in the attic. 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.

Because the simplest and cheapest way to insulate an attic is to add material to the floor. That said air resistance and interference such as vent grates reduces the area of true ventilation. 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.