If you can extend the life of your roof shingles by five, six or seven years, reduce your energy bills and save money on repairs to rotting facia and roofing decks, would you be curious to know how to do it?
Natural Resources Canada (NRC) discusses roof ventilation and attic insulation as a natural way to keep the summer heat from entering your home. Read more here.
If all that is needed is roof vents and attic insulation, why are these processes so often done inadequately? Because it can be challenging to vent roofs with varied grades, valleys, dormers, hips, and skylights, and harder still to create an air-tight attic space. Crucial to a roof’s long life, proper venting and insulation can cost more money than some homeowners want to spend to have it done correctly, leaving compromises to be made.
Insulating an attic is an involved proposition. Pot light openings and holes for ducting, more often than not, are improperly insulated. Suppose air-tight seals are not made a priority. In that case, indoor heated air will escape into the attic in the winter and similarly, in the summer your cooler air-conditioned air, although to a lesser extent, will be drawn out through the roof vents by the warm attic air.
Attic insulation and roof ventilation ensure your roof is kept cold during the winter. If attic heat is allowed to transfer through your roof deck and your shingles to the snow accumulated on your roof, that snow will melt. The melted snow refreezes, forcing shingles apart (water expands when frozen), making them susceptible to lifting, curling and drying, which degrades the shingle.
Thawed and refrozen snow can become deep and heavy, leading to eave trough loosening, and facia rot from the constant moisture.
Roof vents cannot stop attic condensation from occurring. Sometimes, there is more moisture that can be expelled through venting alone. That excess attic heat and moisture will transfer to the roof deck, eventually rotting it and, in turn, the shingles.
Not only does the roof deck wetness transfer to the shingles, but when shingles stay wet, their glue strip degrades, allowing the shingles to loosen and eventually blow off.
Granules on the shingle face add a layer of protection, preventing the shingle from drying out in the summer. Constant shingle moisture causes the bond between the granules and the shingle face to deteriorate.
Architecturally interesting roof planes pose challenges to future re-shingling, venting and insulation upkeep. Keeping your roof simple can mean less worry down the road, but that does not stop most of us from wanting what looks the most appealing. That is why Forest City Roofing of London, ON is here to help.
The Building Science Corporation has published an extensive article here to help explain proper venting and attic insulation.
They can be so strong that they draw more air from inside your home (like your expensively cooled AC-air)
Soffit vents are the preferred form of natural in-take venting. They draw cooler outdoor air into the attic to help modulate the temperature.
At the same time soffit vents aid the cross-breeze within your attic; the cool air comes in from the soffit below, the warm air leaves out the top through the ridge venting, capped roof vents and gable end vents.
If insulation gets in the way of that path, all the good intention of venting stays in the attic. Never, ever let your painter paint shut, the small holes of a soffit vent.
Revolving roof vents will not create a suction force that draws in air, which is good to know since capped roof vents, as shown in the diagram here, are a sufficient style of vent to use.
See the diagram below, courtesy of Natural Resources Canada, that shows the basics for cross ventilation of your attic from end to end and top to bottom.