The Importance of Roof Ventilation

Heat and moisture trapped within the attic can increase energy costs, trigger ice dams, and harm roof system components as well as structural and personal objects. Temperatures in the attic can easily exceed 150° F (65° C). The use of washing machines, dish washers, bath tubs, showers, and tumble driers will cause condensation in attics if they are not properly ventilated through the roof. Condensation can be severe enough to be mistaken for a roof leak in some situations. If you are looking for more tips, check out West Allis Roofing Company.

Here are some of the issues that can arise from an attic that isn’t properly ventilated.

Sumps between rafters (deck deflection) can occur because a plywood roof deck can warp or deteriorate over time (often several years, sometimes just a few years) and become spongy and unsafe to walk on. Since one side of plywood decking has to “breathe” by being exposed to circulating air, this happens. The plywood’s adhesives can deteriorate or fail. Condensation can lead to the development of dry rot.

Water vapour can condense first on everything metal in the attic, causing it to rust. Metal plumbing straps or straps holding HVAC ducting may rust in two, causing the ducting to fall on top of ceiling joists or through a suspended ceiling. In humid climates, this issue is more prevalent.

High inside humidity (40 percent or greater) combined with cold outside temperatures can cause frost to develop on the bottom of the roof deck in colder climates – usually where the average January temperature is 32° F (0° C) or colder. In the glossary, look up Dry Rot.

Insulation can trap moisture, lowering its R-value and providing a favourable atmosphere for the growth of moulds, spores, and fungi, both of which can be problematic. In the glossary, look up Dry Rot.

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