► Here are some problems associated with ventilation in Montreal (in homes and businesses).
1. Sumps between rafters (deck deflection) can happen because after a few years, a plywood roof deck can warp or deteriorate and become spongy and dangerous to walk on. This occurs because one side of plywood decking needs be able to "breathe" by being exposed to circulating air. The adhesives used in the plywood can deteriorate or dry rot can occur because of condensation.
2. Water vapour will condense first on anything metal inside the attic; this will eventually cause the metal to rust. Heads can rust off nails, metal plumbing straps or straps holding HVAC ducting can rust in two, causing the ducting to crash down on top of the ceiling joists or through a suspended ceiling.
3. In colder climates, generally where the average January temperature is 0°C or colder, high inside humidity (40% or greater) combined with low outside temperatures can cause frost to form on the bottom of the roof deck resulting in eventual dry rot and mold.
4. Insulation can trap moisture which will reduce the R-value of the insulation and create a nice environment for the propagation of mould, spores and fungi, which will also cause problems.
5. Mildew is damaging and can cause health problems.
6. The roof system itself will deteriorate prematurely.
7. Ice dams will form.
Let Master Roofers of Belgrave help improve your ventilation. We will suggest and supply the best number and configuration of vents to help improve the ventilation in your roof. Ask us about Maximum Ventilators and their benefits.
Trapped heat and moisture can raise energy costs, cause ice dams, and damage roof system components as well as structural and personal items located inside the attic where temperatures can easily reach 65°C. Condensation that forms inside attics can be caused by the use of washing machines, dishwashers, bath tubs, showers, and tumble dryers unless these items are properly ventilated through the roof. In some cases, the condensation can be bad enough to be mistaken for a roof leak.
There are many types of attic vents available today. There are static vents, power vents, ridge vents, turbine vents, soffit/cornice vents and gable vents. These all come in a wide variety of sizes, styles and shapes. Some will ventilate better than others depending on the roof configuration, attic size, climate, etc. Each roof will be verified prior to offering ventilation repairs or corrections.
To properly ventilate an attic, two types of vents are needed. Intake vents, which are located at the downslope edge of the roof (a.k.a. eaves) and allow fresh air into the attic; and exhaust vents, which are located near or on the ridge line of the roof and allow air to leave the attic. The use of an exhaust vent in conjunction with an intake vent uses the natural forces of wind pressure and thermal effect, collectively known as the Stack Effect, to ventilate the attic space. HINT: Make sure your attic insulation doesn't block the intake vents. If necessary, use baffles to keep the insulation back from it.
When visually inspecting a roof and/or providing estimates, we can only see so much. During warmer months, condensation problems may not evident on the exterior or interior of the roof structure. It is important to let your roofing specialist know about any reoccurring condensation problems. It must be remembered that a roof membrane itself is not the cause of condensation. The roof is the envelope being affected and not the origin of the problem.
► Contact The Master Roofers of Belgrave to ventilate the roof of your Montreal-area home.