Dryer vent & roof deck gap

[Jack Wingo]

House was built in 1999 and roof covering replaced in 2017. There's an open gap between the clothes dryer vent duct and roof sheathing. Did code require sealing gap at time of construction or when re-roof? If so, what is the code?
Thank as always for your help
Jack

[Jerry Peck - Codeman]

Jack,

For a dryer vent, versus a Type B Gas Vent, there are no minimum clearance requirements (a Type B Gas Vent has a minimum of 1 inch clearance to combustible material).

For a dryer vent, there are no maximum sizes either, as long as the flange of the exhaust cap on the roof adequately covers it for flashing purposes.

Keep in mind that the minimum clearance for a Type B Gas Vent is 1 inch, which that looks to be less than, so it is likely not 'too large' of a gap - but the only way to know would be to the size of the flange on the roof cap.

[Jack Wingo]

[Jerry Peck - Codeman]

[Jerry Peck - Codeman]

Jack,

I was looking at your photo on my phone before, back at my office on my computer, zooming in 400%, and I see the metal roof cap exhaust vent showing up past the plywood roof sheathing.

That indicates that the dryer duct is 'just shoved up into' the exhaust vent roof cap, but the dryer duct and the exhaust roof cap are not sealed to each other, and I see what might be some lint at the top of the dryer duct (but not what I have typically seen with dryer duct/exhaust vent roof cap connections like that - maybe that was recently cleaned?

Regardless, the dryer duct is to be sealed to the exhaust vent roof cap.

[Jack Wingo]

[Jerry Peck - Codeman]