I want to have an 8" metal vent installed for a bathroom master fan. I
have a tar and gravel roof, and I am wondering what the correct
procedure is for installing the vent. I talked to multiple companies
who wanted on the order of 1200.00 to do this. Those quotes seem
unreasonably high. The roof is a 2/12 pitch tar and gravel roof in the
detroit area. Anyone have any thoughts on how to install the roof
flashing and vent pipe?
I understand I have to cut the hole, but do I want to chip away the
gravel out of the tar first, before cutting through? Also, does the
flange on the pipe jack need to go under the tar and tar paper, or does
it merely go on top, and get liberally taped/tared/taped/tar.... ?
Also, what can I expect to find under the top layer of gravel and tar?
I assume more tar and tar paper, but will the flange "slide" under the
tar paper to the plywood, or do I need to cut back the tar to the
*outside* of the flange on the pipe jack ? the roof base I am going to
use can be seen at http://www.artiscaps.com/roofbase.html . I am going
to use the adjustable 8" one
The higher the flange is in relationship to the roof grade, the better
it'll shed water. So, set the jack on top of a fresh skimming of tar
and nail it down, lightly tar the flange top, tape and tar 'n gravel.
Ok. So it is really not like a shingled roof at all, because in this
case, even the part of the flange closest to the peak of the roof is on
top of the actual roof surface, where on a shingled roof, that part of
the flange is below the shingle corse towards the peak of the roof.
What is the best method of getting all the gravel out of the area the
flange will sit? most of the gravel is stuck into the exisitng tar.
Also, when I get the gravel out, how do I go about leveling the roof
surface so there will be no voids for water seepage under the flange?
Just use tar? Thanks a lot/
I'd do it by hand, with a flatbar and hammer. It doesn't have to be
perfect. Just get the highest rocks out, then maybe the lesser ones
somewhat. Just use tar. Tom
>snip- What is the best method of getting all the gravel out of the
Ok. Thanks a lot tom, I appreciate the help. Do you have any
recomendations for a type of tar I should be looking for? I am
probabaly going to need something that is fairly thick so that i can
build up a bed of it for the flange to sit on top of. At the same
time, I need something that wont leave any voids between it and the
uneven roof surface. Thanks again
What I used to do when needing to deal with tar; buy a bucket at a home
improvement store, set up a grill, hibachi or whatever, heat it while
getting the site ready then haul it up with a rope when needed, wear
gloves & appropriate safety gear. The hot tar spreads so nicely.
That is probabaly exactly what i will do. I like the hibatchi idea,
though, so I can make my lunch too. Maybee i will just forget the
bathroom vent :) actually, would that be "trowel grade" roofing cement?
Eric in North TX wrote:
Any penetration of a tar and gravel roof at the roof level will eventually
leak because of movement, even if just expansion and contraction. It is best
to build a curb around the penetration. The curb can be securely fastened to
the roof so it moves with the roof. Then the inner part of the curb can be
filled with a flexible sealant up several inches above the roof. A metal
flashing can then be secured tightly to the penetrating pipe, extending like
a tent out over the edge of the curb to keep rainwater and sunlight off of
the sealant. Any roofer who does commercial flat roofs can give you details.
Don- I am sure that is probabaly true, however, the kitchen vent is
done the same way as I want to do the bathroom vent and it would be
very visible from the street. I inspect the roof and add tar as
necessecary every few years anyway, so I am not all that concerned
about the bathroom vent expanding, etc. I will bring up the curb idea
when we get a new roof, the existing roof is 16 years old and is
showing only moderate wear at the corners, which I plan to address when
I do the bathroom vent. Is there anything that can be done besides a
curb that will be better than a simple flashing?
Don Young wrote:
So around the fresh tar, where the flange meets the roof, i would put a
metal sheet, etc, as opposed to packing/droping gravel into the tar?
That actually sounds like a good idea, so i can see if/where any tar
needs to be added during the annual inspection. I may just do that.
Thanks a lot don
Don Young wrote:
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