Class A Chimney touches OSB sheet when exiting through the roof

[webby3650]

I don't know of another cone style specifically made for metal roofs, but there may be another. @webby3650 has more experience than I with various installs using this product. There are several past posts on the Excel flashing that show installation, etc. with chimney other than Excel.

Excel is the only rigid metal roof flashing that I’m aware of.

 

[webby3650]

Ok. Threw me a bit icc excel is 1" clearance chimney up here. So I assumed their flashing may not give proper clearances. But it must just depend on how big of a hole is cut/placement. Duravent doesn't make their own flashing? Or the excel is just a superior product?

Excel flashing allow for the required 2” clearance. Excel also requires 2” clearance

 

[bholler]

Excel is the only rigid metal roof flashing that I’m aware of.

Ventis has one as well

 

[begreen]

Ventis has one as well

Nice, also available in stainless. How does one notch or form the bottom edge to go over the ribbing between the seams?

 

[bholler]

Nice, also available in stainless. How does one notch or form the bottom edge to go over the ribbing between the seams?
View attachment 202107

I just scribe it and notch it. Honestly we typically just use the standard flashing with no issues.

 

[Hogwildz]

If reachable from underneath, and care is taken, you can cut the OSB back enough to meet clearances, without removing or cutting the flashing. If you get most of the way without all the way through the OSB, you can break the rest off. Beats tearing the flashing up.

 

[Squisher]

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Excel flashing allow for the required 2” clearance. Excel also requires 2” clearance

Yes thanks for correcting my morning post. 2" clearance still required. I wàs thinking of 1" construction. Sorry for the confusion.

 

[Beldin]

Sorry about your install. You can have an operating stove very soon. If you cannot get your contractor to fix it immediately, then buy or borrow a fein saw. They have depth gauges on the blade themselves. Your osb sheathing SHOULD be 5/8. I would cut 3/ 8 first and break off flecks until you know for sure. What town do you live by? It may be easier to take the flashing or boot off then cut the hole to proper clearances. I would suggest that it would be a good idea to have someone or yourself take a direct look see at everything on the roof.

 

[webby3650]

If reachable from underneath, and care is taken, you can cut the OSB back enough to meet clearances, without cutting removing or cutting the flashing. If you get most of the way without all the way through the OSB, you can break the rest off. Beats tearing the flashing up.

On occasion some adjustment needs to be made, I just use an oscillating saw to nip away at the decking. We never use rubber boot flashings though, so it may be a little more difficult to prevent damage.

 

[Highbeam]

Your osb sheathing SHOULD be 5/8

We've been using 7/16" for many many years on 24" spacing with clips.

The cone of the flashing is built to allow for 2" clearance isn't it? So you wouldn't have to worry about cutting flashing, there is nothing above the OSB but roofing. Due to the tight location, I would use that crazy oscillating saw that makes all the noise from the attic.

 

[Beldin]

We've been using 7/16" for many many years on 24" spacing with clips.

The cone of the flashing is built to allow for 2" clearance isn't it? So you wouldn't have to worry about cutting flashing, there is nothing above the OSB but roofing. Due to the tight location, I would use that crazy oscillating saw that makes all the noise from the attic.

Sorry, I didn't realize I suggested cutting flashing.

The 7/16 OSB is still allowed here, but I see way to many failed roofs do to the use of H clips between trusses/rafters. Ecspecially if the homeowner has a bunch of valleys in their roof. There are more factors than in most real world situations than engineers understand. How can a computer or draft board know if someone will put more shingles over the last course? I remodeled a barn for a friend of mine who had 5 layers of shingles on his roof. He was an architect, and it took him this long to realize what happens to snow load when this happens. It shouldn't happen but situations like these happen all the time in snow country. Then there is the problem with Ice jams in roofs that were not properly insulated. The OP is in montana. Just trying to help. I will shut up from now on.

 

[Highbeam]

Sorry, I didn't realize I suggested cutting flashing.

The 7/16 OSB is still allowed here, but I see way to many failed roofs do to the use of H clips between trusses/rafters. Ecspecially if the homeowner has a bunch of valleys in their roof. There are more factors than in most real world situations than engineers understand. How can a computer or draft board know if someone will put more shingles over the last course? I remodeled a barn for a friend of mine who had 5 layers of shingles on his roof. He was an architect, and it took him this long to realize what happens to snow load when this happens. It shouldn't happen but situations like these happen all the time in snow country. Then there is the problem with Ice jams in roofs that were not properly insulated. The OP is in montana. Just trying to help. I will shut up from now on.

I wish code required 5/8 OSB, would help a lot. Actually, the price of OSB is so high these days that plywood is competitive. No reason for you to shutup, I didn't realize you suggested cutting flashing either?

 

[begreen]

The OP said the contractor installed a silicone boot which put the circle of screws closer to the hole. There is no flashing cone. It doesn't seem like a jig or oscillating saw would be a good idea here.

 

[webby3650]

Have the installer also add a storm collar. So when the rubber boot cracks water won’t just pour right in. Other than offering no support, most rubber boots would probably hold up for a decent amount of time if a storm collar was used.

 

[Bummer]

I cut the OSB back myself with a right angle grinder, a chisel and a hammer. It was fun! (not really lol) Like stated before the screws from the silicone boot protrude within the 2" clearance in one place so I left the sheet intact in that area. I crawled up into the attic later while a fire was burning and the sheet was cool to the touch so I felt relieved for the time being while a more permanent solution can be worked out. The contractor didn't install a storm collar under the boot. Will have to look into fitting one of those too.

thanks all for your help! really appreciate it. I learned a lot