Roof ventilation is absolutely critical to the longevity of your roof. There are ramifications of improper ventilation, well beyond roof life. Poorly ventilated attic spaces can cause mold/mildew growth, loss of energy efficiency, premature failure of framing members, etc.
Proper ventilation requires movement of air. This can only occur when air can come in at the soffit and exhaust near the peak. Balanced ventilation is as important an aspect of roofing, as installing the shingles properly. For instance, lack of ventilation often causes shingles to overheat and the asphalt to become fragile. This will result in the loss of the aggregate (the small granules on the surface.) Which exposes the shingle to additional damage by UV rays and creates the opportunity for more particle loss which creates a spiral of additional damage.
A common issue, we find in field, is molestation of the soffit venting. Often roofs will have proper ventilation when installed, but something gets changed over the years. It is common for home owners to paint their soffit vents. This paint builds up over time, and chokes the air flow, preventing any real air transfer. This also voids all manufacturers’ warranties.
Another common (post installation) issue is re-insulation of the home. Often attic insulation is installed such that it partially (or completely) blocks soffit venting. Again, this will void your manufacturer’s warranty. This is the most common cause of choked soffit venting. It is easily prevented, by ensuring the insulator uses baffles that keep the soffits clear of insulation and allows proper air movement.
Proper roof ventilation can be challenging, but it is very important to consider when installing a roof. Roofing ventilation means allowing air to flow in and out of your attic area. In many cases, the ultimate goal is to have the temperature of your attic be as close to the temperature outside as possible. Some people get the idea that you should insulate your attic and keep it completely sealed. This is incorrect; you want your home to be sealed and insulated, but your attic should have a nice open airflow at all times. This allows hot air to escape in the summer, keeping the attic cooler, and in the winter it keeps the roof surface cold. You want the roof cold in the winter, because if the roof is warm when it snows, the snow on the roof melts, and then refreezes. When ice gets to the edges, it causes “Ice Dams” which can send water backwards, up through the shingles.
This is a VERY short ‘study’ on the importance of proper ventilation, but it suffices to say ITS IMPORTANT!! Home owners should realize they are a critical part of the team in maintaining the health of the roof (and home.)