Q. I'm reroofing and residing a small home with no soffits. The customer wants to add attic ventilation. I have no problem adding the ridge vents, but there is no soffit overhang to put the eaves vents in. In fact, to have enough space for the vinyl J-channel, I'm having to add an extra 2x4 fascia. How can I get air flow into the attic?
A. Editor Ted Cushman responds: The baseline in the building code still is a ventilated attic and soffit-and-ridge venting is typical. But occasionally a builder runs into a design where there’s no roof overhang at the soffit—and thus, no room for a conventional soffit vent.
Several suppliers have developed specialty products that solve this problem. AirVent has a ventilated drip edge called Pro Flow that you can install under bituminous membrane as you start to shingle the roof. AirVent also offers the Edge Vent, a shingle-over roof-edge component. Both products supply 9 square inches of net-free vent area per lineal foot. DCi Products also has a low-profile eaves-edge intake called SmartVent.
But if you prefer, you can build venting into the fascia using a component such as DCi Products’ FasciaVent, GAF’s Cobra FasciaFlow, or Cor-a-Vent’s S-400 strip vent.
Whichever route you take, be sure to roughly balance the intake venting at the lower edge of the roof with the outflow venting at the ridge. (A 50/50 split meets code.)
A strip of intake venting built into the roof overhang soffit is the traditional method where space allows. Generic vent strips are cheap and easy to find, and carpenters are familiar with the approach. Also, most vinyl and aluminum siding systems in today’s market include components that make venting the soffit easy.
A vented drip edge is effective when there’s no room for a soffit vent—and handy for retrofits where you don’t want to disturb the existing trim. You also can add this to a conventional soffit to boost the inflow capacity. Note: It’s a specialty product and may need to be ordered.
For a low-profile solution, there are vent components that fasten to the roof sheathing before shingles are applied. You have to cut a slot out of the roof sheathing to permit airflow to the underside of the roof deck, so follow the manufacturer’s instructions.
Here’s an option that doesn’t interfere with shingling, but does have to be planned into the exterior trim workflow: apply ventilating strips to the rafter ends or to the subfascia before the fascia is applied. But you’ll need a well-placed baffle to hold insulation away from the vent opening.
