Roof flashing questions

[Pauly]

I got the ceiling support in successfully today, and if it doesnt rain will be planning on installing the roof flashing and the rest of the chimney tommorrow. I have absolutely no instructions about the flashing from the manufacturer, nor have I been able to find any online.

How big a hole is required to give me proper clearance for my class A chimney pipe? What should the clearance be around the pipe?

Should I cut a square or round hole or does it matter?

Does the flashing need more framing support added or are the two rafters it will sit on enough?

Does anyone have a relatively simple step by step guide for me to do this part of the job, so I dont mess it up? Ive been looking online since this afternoon and cant find anything.

thanks for any help you can give me.

 

[devinsdad]

what kind of flashing is it the norm. flat piece with a cone ? clearance should be 2" alll around. My flashing(excel) has a cone that goes over the pipe and the bottom piece is square and boxy.(word?) it is flat on the upper roof part and tapers up to around an inch and a quarter on the bottom edge so I could cut it to fit the ribs in my metal roofing. since I used a cathedral ceiling supposrt I had to cut a 12"x12" hole and the flashing covered it nicely.

 

[Pauly]

yes it is a selkirk flashing for a 2-12 to 6-12 pitch roof, flat piece with a cone, came in the Selkirk ceiling support kit that I bought and has a storm collar that is fit down over the pipe and flashing and is sealed with a silicone caulk ( they call for high temp)

here is the link to the one I got in a kit

(broken link removed)

the one thing that bugs me about the selkirk stuff is poor instructions (and non existent instructions ) and sometimes the instructions are inconsistent in what they name parts and the inconsistent numbering of those parts. If they are going to market a line to home handy persons, then they ought to make the installation instruction not open for interpretation,

 

[Yagminas Masonry and Wood-heat]

Remove shingles around the area where the chimney is coming up and through. Try not to take too many below the chimney. Find the center of the chimney and make a mark on the roof. Center flashing to the mark and reach inside and trace the oval that rests against the roof. Remove flashing and cut out oval. Run a length of chimney up through the roof. Check clearances and correct if necessary. Roof in up to the bottom of the oval cut out. Apply a "u" shaped bead of caulking around the bottom half of the oval cut-out. Drop flashing down over chimney and onto the bead of caulk. Square it up and tack it down with a roofing nail in the upper most corners and one on each side halfway down. Now apply an upside down "u" bead of caulk starting from just under the next course of shingle so it is hidden. Finish roofing in over that bead and make fancy cuts to keep the shingle fairly tight to the upper half of the flashing curve. Put the storm collar on down tight. Caulk top of storm collar. Caulk any worries and yer done.(the flashing that is...)

 

[Pauly]

thanks so much Yagminas - that is just the information I am looking for.

I take then that it isnt necessary for any reinforcing framing under the flashing (parallel to the rafters)?

What is the best type of caulk for the shingles?

 

[Yagminas Masonry and Wood-heat]

Yeah, sometimes if the decking is thin and bouncy I'll add some support or instead of trying to nail the flashing, I'll use screws. If it's a planked roof, I'll always add support to help even out the boards that always spring a bit when you cut through. As for caulking, use something gooey and non-hardening in the hidden beads. Use a thermoplastic like Mulco Supra for a nice rubbery seal on any visible beads. Match roof color or use black.

 

[Hogwildz]

If you save the shingle parts you cut out of from in the hole area, rub the face of them together (granular side) over a pc of paper or something to collect the granulars that fall off. Do this till ya have a small hand full or palm amount. After you are done caulking, any caulking on the top side of the roof, you can sprinkle the granulars over the caulk, lightly press them onto the caulk and it no one will ever see the caulk from the ground. Works very well.

 

[Pauly]

thanks again guys