Installing Vent in Tar and Gravel Roof

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?
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Cut a hole, install the vent flashing, and goop/tape/goop 'n gravel the heck out of it. Damn flat roofs... Tom snipped-for-privacy@gmail.com wrote:

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tom wrote:

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
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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. Tom snipped-for-privacy@gmail.com wrote:

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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/
tom wrote:

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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 snipped-for-privacy@gmail.com wrote: >snip- What is the best method of getting all the gravel out of the area the

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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
tom wrote:

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The thickest type you can manage to spread. Tom snipped-for-privacy@gmail.com wrote: Do you have any

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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.
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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:

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"would that be "trowel grade" roofing cement?" I'd think that would be appropriate.
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snipped-for-privacy@gmail.com wrote:

adding this will create a future maintence headache as things expand and contract differently over the years. better to vent out a wall......
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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 Young
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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:

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wrote:

Some sort of metal weathershield secured to the pipe to keep rain (and especially sun) off of the sealed area would help. You might want it easily removeable for inspection. Don Young
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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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wrote:

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