When you install a new roof on your existing home or business or when you are building a new structure, (which will have a roof on it), it’s a good time to brush up on ventilation requirements.
Over the years ventilation knowledge and technology have changed. I have been in old buildings and residential homes which have no vents at all. I have also seen 10 year old homes with improper or insufficient ventilation. Proper ventilation will provide you with an attic that is not too hot or moist which can cause problems. Bad ventilation can allow mold, condensation, wood rot, shortened shingle roof life, higher energy bills, etc. I have been in attics that are completely wet to the touch and by sight on the bottom side of the roof sheathing because of lack of vents. We vented it and it dried right up. When getting roof consultations or estimates, ask the contractor if your vents are ok for your home. He should know much about it.
A proper ventilation system is balanced. The intake at the eave should be equal to the exhaust at the ridge. This makes for an even flow of air to keep the attic and roof deck in ship shape. Different climates have different air volume requirements.
Make sure you do not have conflicting types of vents on your roof like a power fan beside a slant back gravity vent , for example.These are both exhaust vents and that fan will probably pull air into that slant back vent making it an intake vent. This is like a short circuit in electrical systems.
This is just basic and general info about roof and attic vents. Your roofing contractor should be able to evaluate your home and either replace your vents with new ones, if your system is good, or change the way your house vents all together. It will pay off in the short and long runs if you handle it at new roof time.
Bad ventilation will void your shingle warranty and shorten the life of your roof. This is true in asphalt or wood shingles or shakes. We like to use AIRVENT products because of their quality, availability, variety, customer service, and training.
Many architectural or dimensional asphalt shingle roofs are now made with limited lifetime material warranties if installed and vented properly. Our favorite type of exhaust roof vent is ridge vent because it is at the ridge and is continuous ventilation which leaves no “hot spots” under the roof deck.
Thanks and have a good day!
Robert Andrews II