Reinforcement for Large
Copper Foil Project.

by Sue Callahan
(New Bern, NC)

I am constructing a large window (not to be exposed to the elements) that is 39" X 60", in copper foil. I would normally use lead came for a project like this and reinforce with rebar. However, my customer wanted copper foil. I am trying to decide how to reinforce. I always frame in zinc came for strength and I am using 1/2" H channel zinc for this window. When using restrip, how much is enough? I can not find guidelines for how much to use. Do you think restip would be enough strength for a project of this size? I can use rebar, which I am much more confident about (it has stood the test of time in many historical windows) except that the design does not lend itself well to the straight horizontal lines of rebar. I have sent for a book on reinforcement guidelines from SGAA but it has not arrived yet and may not answer my question about restrip. Please help if you can, Thanks,

Sue Callahan
Visions In Glass

Hi Sue,

That's one big window to be foiling. I'd be leading it too! A lot faster and easier, in my opinion.

Reinforcement is necessary on larger windows. As a rule of thumb, a window more than three square feet should be reinforced.

Use restrip every 1 to 1 1/2 feet on a panel as large as yours. I'd run it in both directions, (side to side as well as up and down) and make sure you use it on any hinge joints as well. Run the restrip from edge to edge in both directions.

Restrip is extremely strong. New data is showing that it is as strong as rebar. Of course, rebar has been around a long time, and restrip is new in comparison, so time will tell. I'm sure we won't be around for the final analysis!

I'm trying to picture the panel in relation to one I built for our game room. It is 5 1/2 feet long, and 1 1/2 feet high. It is foiled, reinforced with restrip and has a zinc frame. It has been in place for 5 years, near a door that opens and closes frequently. It is not exposed to the elements, it's between the game room and a hallway. It has no bows, cracks, nothing at all to indicate that it should have had more reinforcement.

With the restrip and the zinc frame, you shouldn't have to worry about the panel flexing. It should be as solid as a rock. However, you be the final judge. Since I can't see the panel, I can only give you advise on what you have told me.

I hope this information will help you make your reinforcement decision,

Comments for Reinforcement for Large
Copper Foil Project.

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Feb 26, 2008
small window in cabinet
by: Susan

I've read your comments on the large window reinforcement, and that reinforcement should be done on cabinets or doors that will be shut. My question is.... what about a window in a cabinet that is not used excessively that is 3 3/4 by 10 1/8th? Does this need reinforcement? I was planning on doing the copper foil method. Thank you for your time.

Susan, I have moved your question so that it is a separate question rather than a comment. That way everyone will see and benefit from it.

Jan 03, 2008
my decision
by: Sue Callahan (original sender)

Hi Sue, and thank you for your comments. I decided to use both restrip and rebar. If that much reinforcement fails we'll know the window was just too darn big!!! (or that it should have been done in lead came) I got my chapter booklet from SGAA and they suggest no window be done in one section that is bigger then 14 linear perimeter feet. Mine was 16.5 feet. They also state that lead came is more resilant and lets the glass expand and contract with temperature changes, allows the glass to flex, etc. and therefore is the better choice for any window, esp. one of this size. The copper foil method is much more rigid and resistant to the needs of the glass and therefore a poor choice in a confined space such as a window. If the glass expands and there is no place for it to go (the cushioning of lead came)it will crack. I just can't imagine how you could flip a piece of this size done with lead came, without glass coming loose from the came, etc. As is was in copper foil, it was very difficult to flip. It took three people, and we sandwiched it between ceiling tiles (rather awkward maneuver)and even so, one piece cracked and had to be replaced. Ugh. The finished window looks beautiful and lets hope for the best as far as durability. I certainly built it strong. I'm hoping the H channel zinc border came is enough to allow for expansion. Thanks again, and let me know if you have any comments on "flipping" a large window in such a way as to not break any glass. Thanks, Sue Callahan, Visions In Glass

Hi Sue,
I'm in total agreement with the SGAA. However, I didn't even go into that as your question was about reinforcing copper foil. Whenever we have to construct such a large window, we not only do it in lead (our first choice for any size window construction) but we usually make it in 2 pieces with U came at the bottom of the top piece and reinforced H came at the top of the bottom piece. We then fit the 2 pieces together at installation time. That makes the window much easier to handle.

Turning a Large Panel

As for turning such a large piece. We use 2 pieces of plywood the same size as the panel. One piece has a narrow board nailed to the bottom edge. The window sits on that board, with the bottom of the window resting on the ledge. The other board sits on top of the window. We then clamp the two baords together, along the sides.

Then we slide the whole thing over the edge of the table until we can tip it and slide it off the table, upright, on the floor. At this point we "walk it"/turn it around and reverse the process of getting it back on the table. We've had some huge church windows, that we've restored, and had to turn them over in this manner. We've never had a broken piece doing it like this.

I hope this helps you in future work.

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