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14 Posts
Discussion Starter · #1 ·
Hey guys,

I'm installing a new bathroom exhaust vent. I've installed many on typical asphalt shingle roofs. Now I have come across a flat torch down roof. I've never delt with this type of roof. I need help with knowing what type proper collar to use and proper installation technique to ensure a proper seal.


12 Posts
electrician here... the building owner wants me to install the ba exhaust fan and vent it thru the flat roof. theres really no way to exhaust thru the wall because of the height off the ground. access

I installed plenty of roof jacks
and worked on my own attic fan.'
But i want to make sure i dont let the building owner flat roof leak.

so here is the roof jack i found will that do?
then I was going to seal it up.
Any help would be appreciated!!
thank you

I found this:
American Aldes 4" Roof Cap for Dryer Venting - 22 041

Can I
mount the fan
run some insulated flex duct a short distance
using 45^ bends instead of 90^
then cut a 4" hole for the collar
secure the duct to fan and collar
go up top and lay down a bed of henrys 204 Plastic Roof Coating Cement
butter up the hole and lay down the flashing
squish it down till the 204 comes oozing out the hole
butter up another layer of 204 around the seam
lay down a layer of Henry 181 4 in. x 150 ft. Asphalt Glass Fabric to sturdy up the seam
come back in a month and paint it with some white roof paint like Henry 0.90 Gal. 289 Elastocaulk Acrylic Roof Sealant

14,169 Posts
Let a roofer do it. Then its on them when it leaks.

Your insurance will have a sh!t fit when they are paying for a 50,000 dollar house repair because you, or your customer were too cheap to call in a roofer.

Not worth the risk.

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