since no one has answered you so far, i would suggest posting this question in the forum you thought first.... which is the greenhouse forum. they are a friendly group over there, and some of them have used old windows for various structures. maybe you'll get some good ideas from them.
good luck!

Someone just posted pics of a greenhouse they made out of old windows. I think it was on the round robin mnf after dark thread. It was really cool! She talked a bit about how it was made too.

Allison

Thanks Allison and Zubaby...those are two great sources. I'll check on them both to see what I can learn!

Lori

Lori, Look for Mao-tse-mom's post in the Cottage Garden forum...oh, my, it is the cutest thing you've ever seen-- all made by her husband.

http://forums2.gardenweb.com/forums/load/junk/msg051641444416.html

Just post on this thread and she'll see it and offer up a pic of it all finished and painted. I just love it!

Lime

This is my first posting in many years but when I saw this I had to tell my story. My husband and I built our second greenhouse last year and just love it. We had new windows installed and used our old windows for the glass. First we built a 12 by 16 frame out of treated lumber with a fiberglass ribbed roof. The first year we used plastic for the sides and the second year after my husbands shoulder surgery we put in the old windows. We hinged three windows for circulation when needed and we should have put in one more. We can fix that later on when the plants are out. Anyway it works like a charm. The benches are made of cement blocks pillars and we put closet wire shelving across the top. The openings of the cement blocks are filled with 2by4's making another shelf for my flats. By using the wire shelving, the plants have lots of drainage and they don't rust. We have the shelving in a U shape. Electric was added this past fall and has been very handy. I used extension cords before and this is much better. During nights when the temps get to freezing, I turn on a radiator type heater and a fan pointed to the ceiling to keep the air circulating. The temp keeps about 10 degrees above the outside temp. I do not use this all winter, just for starting seeds in the spring. Works great for us. This spring we have to paint it. I forgot to mention that we have this connected to a wooden shed that is 12 by 24 feet. Linda44