The great thing about tin-knocking and hand seaming is: any surface that has a pitch can be clad and seamed through without the use of soldering. Double locked, standing seams when properly executed can be carried through almost any complicated detail on a roof: again without the use of solder, petrochemical sealants, or any other magic goop or temporary methods.
The example I’m using to demonstrate this concept is an irregular hip roof on a small chimney cap pictured below. This seam intersection is a common problem for those constructing a larger, long pan roof. This would be the intersection where all 4 pan-tops merge together.
I’m going to show the process of how to construct the 4-way intersection at the top of the pyramid with double folds all the way through.
We start by laying out the pans. This pan was laid out from the plywood template. The same geometry used to calculate the triangles for the irregular roof are used to form the copper pans. Of course I have to add more material for the seams but the bend line is essentially the same as the plywood seam.
Next, I fold the seams over to make room for the next pan to be installed
The pans must be installed in a sequential order so good labeling and organization is a must. This is even more true of a larger roof with many transitions. Every seam must be pre-planned in the layout stage.
A little further along and we have one seam completed and “pinched” to run behind the vertical seam in the shot.
We haven’t cut the seam, but instead pinched it to run in a different direction. Think of making the pocket fold when you wrap the corner of a present. It is similar to that.
Once one side is seamed together the whole thing must be laid down again to make room for the other side.
Finally with both sides seamed through and pinched, the final turn can be added:
With this step completed, the intersection is double folded all the way through, and water-tight without the use of solder or any other material.
Casa Buena can provide expert fabrication services for any historic permanent roofing projects involving slate, tile, and standing seam steel or copper.
You can see the finished project on Parade St. in Providence.