I'm sure there are those who have had success with old windows, but they will complicate the construction especially if they are not uniform in size. (Placement of studs and purlins, sealing cracks, etc.) Also, if you plan to use your gh year 'round, glass is a poor insulator. And finally, a stray falling pine cone, branch, or baseball will not only require a time-consuming repair, but could endanger sensitive plants and/or children.

In Massachusetts, your winter heating/insulating needs will be significant depending upon what you want to grow. I'm not a fan of HFGH, and many members here on this Forum have a love/hate relationship with theirs. But I think you'd be happier with HFGH than a custom-built one with old windows.

BTW, HFGH requires retrofitting, especially in higher-wind areas, and don't skip the site prep.

-Bruce C.

thank you for the advice I was just trying to think of the pros and cons I will be using the greenhouse for seed starting and housing some of my house plants the only reason I was thinking of building is that my father in law builds houses for a living and so I know there would be help

You may have already done these calculations. But if you plan to keep house plants over the winter, you probably don't want temperatures to dip much lower than 55F. If your lowest wintertime temp is around 0F, that means you must have the capability to maintain a 55F differential. With a 10x12 HFGH (which uses 6mm twinwall panels), you're looking at a requirement of nearly 21,000 BTUs.

If you use the structure as basically a "cold-frame" for starting seeds early, your heating requirements will be substantially less.

-Bruce

I built a GH from old windows. I made frames and used two windows with a three inch air gap between them, then I just assembled the frames into a structure. Sonce my windows were already double pane, I have four pieces of glass and three air pockets. The efficiency isn't bad at all.

thank you for all of the advice but i quess we are going to go with a HFGH

do yourself a big favor and READ READ READ all the blogs/posts etc. on the how to's for the HFGH..It will help you tremendously.