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Joe1. 08-22-2010 01:22 PM

Copper dormer recess pan
Hi everyone,

The roofers that we hired are wrapping up their work on our house, and it's time to finish off the gable dormers we built. With the dormers, we recessed them into the roof slightly, so in front there is a small 2:12 pitch roof section that's about 16 inches long and at the face wall of the dormer it is about 10 inches tall. So we have to make a small pan with triangular sides and tuck it under the window. The problem is the roofers are saying they cannot solder the copper recesses for the dormers. They should know, but they don't. Anyway, I'm going to try to do them myself, having some experience with soldering and having a friend who sells copper roofing materials.

Anyway, can lead coated copper be soldered the same way as regular copper?

Also, it's important, I imagine, to make the recess pan in as few pieces as possible. Do any of you guys have any tips on this process? If I have to make it in several pieces, where are the best places to make the flat seams (on the vertical corners, for instance)? Perhaps one of you have a link to some photos or a good information source?

Any help would be greatly appreciated.



tinner666 08-22-2010 09:35 PM

Lead coated is easier than plain copper. It doesn't need pre-tinning. What it does need is to be mechanically brightened. I prefer using the small 6" long stainless steel brushes with the 1-1/2" by 1/2" head. No sand or rust particles to contaminate the seams.

Lulimet 08-22-2010 09:56 PM

Sorry I can't help you but it's pretty sad that the roofers can't solder your copper.

seeyou 08-23-2010 04:46 AM

What tinner666 said. It's preferable to use 60/40 tin/lead solder (vs 50/50) and a zinc chloride flux (Ruby fluid is the brand I typically use). The paste fluxes I've tried don't work well on LCC.

Use a soldering copper (not a torch) and start at the top on vertical seams. Try soldering some pieces on a work bench 1st and then cut through your seams to see if you're getting them sweated properly. Don't go on the roof until you can solder a vertical seam without making a mess. Good luck.

edit: The size dictates how I'd fabricate the pan. I don't know the main roof slope or the width of the dormer. I try not to put seams in vertical corners - they're harder to solder than field seams. Try to fold through the corners and put the seams an inch or so away from the actual corner. Any seams on the roof part should be flat locked. The verticals can just be overlapped.

Joe1. 08-23-2010 09:51 AM

Thanks for the information guys, I appreciate it.

Seeyou, the size of the dormer recess (the width) is 36 1/4 ", and then the dormer side walls go out onto the main roof, and that width is about 43". That's the width of the framing, so sheathing and all it will be about 45 inches, I think. The length of the recess (into the roof) is only 16 inches, with a 2:12 pitch, and a depth (at the face wall) of about 10-12 inches (I forget the exact measurement). And, I think the hypotenous of the little triangles on either side is about 20-24 inches. Also, the pitch of the main roof is 14:12, so fairly steep.

I figured the verticle corners near the windows should be folded, rather than trying to solder a good joint. What I'm thinking is make the little triangles, with a 4 inch overhang (for the main roof), the part under the window, and the main pan and apron (for the front to hang over shingle) out of one piece. So I'd be bending the back up for the windows and the triangles around. In other words, it'd look like an unfolded shirt, and I'd then bend the sleeves around and the collar/neck area foward.

This way I avoid the verticle corner seams, as well as a seam going vertically under the face wall (the latter being not as problematic but good I suppose to make less seams anyway).

With the little triangles, I'd then leave enough on the bottom main pan edges to bend upward, and tuck behind the triangles to form a lap seam.

How does this sound to you guys? The only area (with this design) that I'm not too sure about is the apron to triangle (main roof) flange area. How should this be treated? The apron should rest on top of the shingle, and the triangle flange underneath, but should I just make the the triangle flange come down past the apron or stop at the same point as the apron? I'm not sure how much this matters since only the apron will show.

Lastly, like I think I already mentioned, the framers have already installed the windows, so I can't tuck the copper into the sill (as I've read it is sometimes done). Is it sufficient simply to bend the copper to tuck under the window's sill?

Anyway, any more advise is greatly appreciated.



Tom Struble 08-23-2010 10:47 AM

it needs to go under the window sill flashing

seeyou 08-23-2010 10:57 AM

Sounds like a good plan for the fabrication.

I usually make the apron a separate piece and let it extend past either side of the well. The well pan then locks to the apron and the side triangles lock to the well pan if it's small enough to fabricate in one piece.

The major plane roofing material can then lap over the apron at the sides.

tinner666 08-23-2010 02:55 PM

3 Attachment(s)
You're on the right path. Make the pan at least 1/4" smaller then the well, side to side, for expansion.
This is 3' x 6' and is about 12 years old now. No issues with expansion.

A close up of a joint on it. The only solder in front of the seam is 'run-out' when the seam filled up.

Joe1. 08-26-2010 11:18 PM

Hi guys,

Thanks for the help, I appreciate it a lot.

Seeyou, regarding the apron, is there much difference in making the apron go only the width of the well, rather than all the way to the side triangles like you do? I remember seeing a few examples locally, where the apron goes only to the width of the recess, then the shingle begins. Maybe the apron tucks under the regular roofing there. In my case I can't see how I could make the copper tuck under on each side, because the shingle tab doesn't end up in the right spot for that. The triangle flanges would have to extend past the last shingle in order to meet the overhanging apron below.

Also, the roofers left an overhang, fairly large (2-3 inches) into the recess well (or over the well) on the sides. But I thought that the shingle is simply cut flush with the well. Isn't it supposed to be flush? Or is a slight overhang preferable?

Tinner, regarding the expansion, the roofers installed the ice and watershield in that area. Would it be sufficient to measure from the ice and water shield? In other words, would the thickness of the underlayment be enough to account for expansion? Or should I also subtract the 1/4" from the ice and water shield width. And you're saying the 1/4" less is only for the width of the recess?

Lastly, Seeou, you mentioned "locks" for the triangle to well pan. Do you just mean a regular lap seam? Or do you mean an actual flat-lock? It's a vetical overlap. so a flat-lock wouldn't be necessary would it? And, Tinner, on your work, is that simply a lap seam on the sides? Or did you right angle the sides in order for them to lap onto the well pan itself?

Sorry for all the questions guys, it's just that I have these roofers coming to finish up tomorrow, and a bunch of other work, so I'm trying to get all my thoughts out at once.

Thanks again,


Joe1. 08-29-2010 01:06 PM

Hi Guys,

I' m going to try to get some pictures posted of what I'm working with here. The roofers finished yesterday, and I told them to shorten the shingle overhang to .5 inches on the recess sides. Now, though, I'm not sure how to finish off the triangle ends and the apron, since it seems the shingle overhang will interrupt the flow of the copper apron.

In my case, I don't think I could connect the apron to the triangle flanges (as Seeyou suggested), unless I make a slice into the shingle.

Anyway, I'll get some pictures up of what I'm talking about.

Till then,

tinner666 08-29-2010 07:09 PM

Those are flat-locks on my verticals. Sometimes my inside corners are boxed, sometimes soldered. Whichever feels right at the time.

The shingles need to overlap the sides of the well. But need to be open at the bottom corners for smooth, uninterrupted water flow.

Allow whatever lets the pan float side to side freely. Don't bend the sides to full 90. 80 degrees is fine and should be a flush, if not snug fit at the top. The bottom must have freedom to move.

I looked but don't have a pic of the 'exit' detail. It involves folding the metal out and wrapping the corner, Then coming back over with the shingles, but leaving the corner itself open.

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