The Importance of Roofing Ventilation

Roofing Ventilation

Ventilation Maximum, WeatherPro 50

Proper roofing ventilation in the attic is best practice and very important to the long-term health of your roof and contributes to a comfortable living space. Each season has its own factors for which to accommodate.  Care must be taken ensure that good ventilation is adequately planned for and properly executed. While not a complex task, good ventilation is a vital part of a well-functioning roofing installation.
In the summer:

  Most shingles are in the direct sunlight for the greater portion of the day.  A black roof can get up to 70° C.  Much of this heat is radiated into the attic, where the air can become very hot. In an ideal situation cool air will come into the attic through the soffits on the house and create natural convection.  This will create a current up through the space and out the vents near the top of the roof. If ventilation is not allowed to occur properly shingle surface temperatures can reach in excess of 85° C. Insulation takes a great deal of energy to change temperatures. Sitting in a hot attic all day will allow it to accumulate a huge amount of heat energy, which will then radiate into the living area during the evening hours and cause the house to be very warm for hours after the sun sets. Shingles become very soft at high temperatures, and all this excess heat will keep them softer for longer. As a result they are more susceptible to wear and tear. The shingles will begin to curl in a tell-tale pattern and the functional life can be severely limited

In the winter:

  Warm humid air will move from the house into the attic. It will freeze over the trusses, roof deck, and insulation. This can lead to a centimetre of more of ice covering the structure. When the weather warms up this water can cause havoc. In extreme cases leaks will begin to appear in the ceiling. Perhaps more detrimental is when the water does not show signs inside the home, but soaks into the wood & insulation that make up the attic. Bacteria can flourish in the dusty attic, and the roof deck can degrade and rot. The plywood or OSB will start to buckle and wave, and can feel spongy underfoot. At this point repairs can become moderately costly.

Ventilation is typically separated into two classes:

Passive Ventilation – For the most part, a house can be adequately serviced by passive vents such as the turtle vents that are standard on all our quotes, or ridge vents that are typically used over vaulted ceilings or where there is limited attic space.

Active Ventilation – Driven by outside forces, active ventilation can offer an improvement over passive by forcing a greater exchange of air. One of our standard upgrades is the Ventilation Maximum system.  It uses no electricity but interacts with decompressing air coming over the ridge line and causes air to be pulled out of the attic. We also offer installation of solar powered vents, as well as a more robust electrically powered & automatic-thermostat controlled model.

During our free estimates at Stalwart Roofing we frequently come across houses that do not have proper ventilation installed. It is standard procedure for us to asses the home and ensure that the customer is aware of any changes that are necessary to the current systems.

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