Functions of a roof system
The average roof makes up over 50% of the homes exterior and because it is the primary defense against the elements it must not only look good but perform well. The roof of your home serves a couple functions. Obviously it’s major function is to protect you from the elements but secondly it must be designed in a way that keeps your home comfortable through proper ventilation and insulation.
Ventilation
The roof system is designed to breath. It must draw air from the soffits (under side of roof) and exhaust through the top of the roof. If the roof lacks either proper intake from below or exhaust from above the following conditions are likely to occur.
1) Baked shingles, some poorly ventilated attics will get so hot (up to 160 degrees or more) the shingles will bake, making them crack and deteriorate at an accelerated rate.
2) High cooling bills in the summer, if the heat that is built up in your roof's attic can not escape, it will come into your homes living areas and create an uncomfortable environment.
3) Moisture problems, trapped moist air can cause rotting and mold problems in your attic which not only can be costly to repair but bad for your health.
4) Rotting / spongy decking, if the under surface of the decking (or sheeting) has moisture and condensation against the surface it will rot and weaken the decking
Here is a diagram showing how proper air movement should be in an attic. Hot air naturally rises and cool air is drawn from below to replace it. It is important to have both an exhaust toward the ridge of the roof and an intake on the lower edge.
1) Baked shingles, some poorly ventilated attics will get so hot (up to 160 degrees or more) the shingles will bake, making them crack and deteriorate at an accelerated rate.
2) High cooling bills in the summer, if the heat that is built up in your roof's attic can not escape, it will come into your homes living areas and create an uncomfortable environment.
3) Moisture problems, trapped moist air can cause rotting and mold problems in your attic which not only can be costly to repair but bad for your health.
4) Rotting / spongy decking, if the under surface of the decking (or sheeting) has moisture and condensation against the surface it will rot and weaken the decking
Here is a diagram showing how proper air movement should be in an attic. Hot air naturally rises and cool air is drawn from below to replace it. It is important to have both an exhaust toward the ridge of the roof and an intake on the lower edge.
