I'm not sure about the buildeazy plans. I haven't heard of them before you might try Sun Dance Supply. I seem to remember plans to build a greenhouse on their website. Also, you might want to reconsider the width of your greenhouse. Perhaps scale down to 8' or up to 12'. I had put some thought into building my own greenhouse recently and what I found was 10' didn't seem to work as well as 8' or 12' because of bench/planting bed space along with walkway space. Heres what I mean: With a 10' wide greenhouse if you have a 2' wide walkway down the middle then you are left with 4' benches/planting beds on either side. For benches thats a long way to reach over, it may not be as big of a deal with planting beds. Your other options then become to add a second walkway and reduce the width of your benches, or widen your walking space so that your benches aren't 4' wide. The conclusion I came to was that it was abetter use of space to either cut back to 8' wide with one walkway, or go up to 12' wide with two walkways leaving me with three rows of benches. Anyways, just a thought, I know its a bit off topic from what you asked, but I thought it might help.

I believe you should use a sealer between the bottom sill of the GH and the foundation. The 3- 1/2" wide foam that comes on rolls for use under 2 x 4 sills in new construction would work as well for a GH. Then, if you run a bead of 100% silicone along the edge of the sill inside and out, you should never have an issue with cold air intrusion. How you will attach the sill to the foundation will depend somewhat on how it's made, but it's one place for which stainless steel is not a luxury, regardless if the fasteners are simple screws or large hex's- most especially if the GH frame is aluminum. But regarding heat, and the best time to think about it really is now, before you start erecting the GH.... Could you give up a few inches of ceiling height, by raising your floor a bit? If so, then you might want to look into floor heating cables. Warm floors invariably translate into warm air, especially if you add some ceiling fans, which are cheap to buy and operate and can make a nice difference in heating costs as well as much better summer cooling and of course, the continual air circulation so vital for plant development. Depending on the temps you want to maintain in winter, you still might need an additional heat source, but not much. BTW: It's easy to waterproof the controls on oil filled heaters. Set the temp, then slip a small baggie over the controls and hold it on with a rubber band.

Johnny's seed. Dan

Terry, "I was hoping that there was something that I had missed that could be used to assist in heating a glass house, though." As Nathan suggested, there are things you can do. One simple thing is to use dark colored cinder blocks, or an equivalent, for your floor and as supports for benches and shelves. For a lean-to greenhouse, a whole wall of cinder blocks could be a good solar absorber on the lean-to side. They will absorb some heat during the day and re-emit it during the night. If I can't find cinder blocks locally, I may paint some concrete blocks a dark color. They can provide your greenhouse with some simple "thermal mass". I wouldn't rely wholly on solar heat, though. But a simple thermal mass can reduce the load on your active heating system. If you live in a cold climate, it makes sense to excavate down below the frost line and lay in some durable foam insulation, and put some gravel or crushed rock over that and maybe some heat-absorbing pavers to walk on. That way your immediate foundation area can serve as a limited thermal mass without wasting energy trying to "heat up the whole planet" (grin). As soon as you complete the excavation below the frost line, that might be a good time to lay down a layer of steel hardware cloth as a rodent barrier and lay your foam insulation on top of that and your gravel and such on top of that. Some rodents apparently enjoy chewing through foam insulation. In this area of Maine the chipmunks are impressive diggers and we have voles throughout our back yard. And you certainly don't want mice or rats in your greenhouse. I'm in the process of following my own advice, excavating a foundation for an 8x16 lean-to greenhouse kit that I expect to arrive in two or three weeks. The snow and rocks are kind of slowing me down. Gotta get out there now and chip away at a few rocks. MM