As far as roof top and attic ventilation goes there are basically four options. The first option being the standard square low profile vents. They come in various sizes and ventilate a specified amount of square footage of attic space per vent. So once the square footage of attic space is calculated then depending on which size vent is chosen that will determine the number of vents needed. We are often asked are the low profile vents still effective when covered in snow and the answer is yes....they are designed to function even when covered in snow. These type of vents also come in vinyl/plastic and metal composition. We prefer to use the Duraflo brand.
The next type of roof vent is a turbo or turbine vent which now comes in different sizes and shapes and they also come in plastic and metal. The steel turbine vents are the ones most will be familiar with. Turbine vents operate on a bearing system and are required to be spinning in order to be ventilating. We prefer not to use turbine vents as the bearings like any other mechanical part can seize and stop working. Instead we prefer to use turbo vents which have built in baffles and do not require any motion to be ventilating. Both have a similar raised profile with a round top on a pedestal base. Turbines are available in metal while turbos are available in vinyl/plastic. Again we prefer to use the Duraflo brand.
A step up from the turbine or turbo vents is something called a Maxi vent - also made by Duraflo. It is a pedestal vent with a square top and can have various louvred tier levels for more ventilation per vent. Again...living in Ontario and especially our service areas of Orillia, Barrie, Midland, Gravenhurst, Bracebridge, Muskoka, Simcoe and Georgian Bay we experience some pretty large amounts of snowfall and sometimes it's best to have a higher profile vent on the roof depending on your pitch and attic space.
The "Cadillac" of roof venting is considered to be ridge venting. It is a cleaner look with less clutter on the roof but it is not always the best choice depending on your roof configuration and amount of actual roof ridge space available. Ridge venting is cut into the ridge or peak of the roof and ventilation is installed right in that area. If you have a cottage style roof then there may not be enough top ridge space for adequate ventilation. If you have cathedral ceilings in your home then generally ridge venting is your only option. Ridge venting comes in two forms...rolled and rigid. Rigid is just that and has the best chance of staying flat and clean looking along your ridge line for the duration where as rolled ridge venting can become warped looking over time.
The last form of attic ventilation we will talk about is gable vents. These are vents that are in the peaks of the walls below the roof line. You can purchase many decorative gable vent caps in various shapes, sizes and colours. Octagon, square, rectangular, triangular and round are the most common shapes we see.
Finally, as mentioned in the insulation blog it is important to have good soffit and baffle ventilation as well. If you have an older home with solid wood soffiting you should consider have holes cut into the soffit area approximately every 2-3 feet and either cover the holes with soffit vents or replace the wood area with ventilated aluminum soffit.
Other types of roof vents are related to plumbing and exhaust. A plumbing stack is usually a black plastic round tube you see protruding from the roof. It sends the bathroom gases out of the house. At the base of the stack is a plastic or neoprene gasket that should be replaced when your shingles are replaced. Exhaust vents are used to exhaust moisture from either your bathroom fan or kitchen fan out of the house to the outside. Sometimes these areas are ventilated through the soffits. It you have shingle failure close to a plumbing stack or exhaust vent area your attic space should be checked to make sure the connections have remained intact and that warm moist air is not being exhausted solely into the attic space instead of up and to the outside.
Ensuring your roof has adequate ventilation is one of the major and key components to maintaining shingle warranties and extending the life of your roof.