Roof Sheathing With No Vent

The map at right which is based on table r806 4 of the irc lists the minimum r values required to prevent condensation in unvented assemblies in various climate zones.

Roof sheathing with no vent.

Venting prolongs the life of the roof. Static roof line vents are effective for ventilation but generally aren t recommended due to issues with leaks. Gable vents may circulate air through only a small percentage of your attic. Eventually the fascia soffits and even the roof sheathing will rot.

One of the major concerns of shingle manufactures is that un vented roofs will increase the temperature of the roof sheathing and shingles which would lower their life span. Ventboard is a proprietary innovative sheathing panel for roofs siding and flooring. The roof as you have it with soffit vents and air chutes but no high vent is a suitable design except for homes in the coldest climates with high indoor humidities. Additionally ventboard now has an international patent pending pct us2011 048786.

Patent pending 12 987 832 patent pending 13 016 320 and patent pending 13 539 919. Roofers use a circular saw to cut a long slot along the roof ridge if there isn t one then cover it with a plastic flap as shown or a flexible vinyl matrix. An unvented roof assembly is possible only if you keep the roof sheathing warm enough to prevent conditioned air from condensing against it. There are three extensive patents filed.

The problem was there was no overhang or soffit eave so at the end of the raffters we put a new 10 board. If you have gutters but no gutter apron to stop the water it will wick behind the gutter. Openings along the sides allow air out of the attic cooling the space and lowering your air conditioning bill. Bill rose of the university of illinois states in an unpublished report that researchers have compared the shingle temperature of both vented and un vented roof systems.

In northern climates the ceiling below an icehouse roof should be airtight and have a vapor retarder because the underside of the sheathing can get cold. This board was at an angle not straight plum like the wall just under it. When water flows off the edge of your roof some of it clings to the underside of the shingles and dribbles toward the fascia. Without baffles blinders that prevent outside air from crossing over the vent a ridge vent may create almost no ventilation at all.