I've been reading this forum for a while now, and I have to tell you all that your ideas are down-right INGENIOUS! I am so envyous of the gigantic greenhouses of many of you! I am also trying emulate the resourcefulness and ingenuity of those of you on limited budgets and space, who are making the most of what you have.

In my own situation, I am looking to extend my growing season, without emptying my wallet! Last year I used a cold frame to give myself a bit of an extension, but am hoping to vastly improve the LOOK and function for next spring!

Here's my current HOPE and design thus far.

#1 - goal for the structure (this seems to be the most important factor) - I see the structure as a dual purpose. In late winter/early spring I want to be able to move seedlings into the structure after potting up, OR "winter sowing" (in containers) them IN the structure, which might be MORE effective. And secondly, during the late autumn/early winter, I would like to be able to grow root crops and greens to be used throughout the winter (or at least as much as possible.

#2 structure size - 4' x 12' x 8'(at highest point, where it connects to the house, 6.5' on the other side, as I don't want to have to duck too much getting in!)

#3 location - This would be on the south/southeast side of my house. (most convenient location and most likely spot to get spousal approval!)

#4 special features - This section of my house is an UNHEATED addition with a laundry room and rest room, that is adjacent to a HEATED family room. There is a window to the laundry room in the dead center of the 12' length of the structure. There is also a dryer vent on the extreme left side of the structure.

#5 materials on hand - I have some old windows, that I used for cold frames last year, and some unframed large panes of glass, as well. (I think I will need to ADD some additional materials, but want to use on-hand materials, as final cost would also be important for spousal approval!)

#6 Temp range - lowest temps are around 10-12 degrees. I would want to keep the temp range around 40-45 at night, and about 70-75 during the day.

Here are the questions:

1) Would it be best to make the roof from polycarb, and use the recycled glass for the walls?

2) How much benefit could I draw from opening the window into the lean-to, to act as a heat sink? Warming up during the day and giving heat back at night? How much would that draw on the house furnace?

3) Would I want to use double glazing on the walls/ceiling, rather than single glazing to increase the R-factor? Would it be best to simply use a plastic or bubblewrap on the interior, with a 1 inch air pocket between it and glass?

4) Is it possible to grow in 3 tiers in this structure? Root crops in ground, and two rows above...2nd row 3 feet above ground on the wall, with 9-12 inches of potting mix, and 3rd row 3 feet above ground, with 9-12 inches of potting mix? (The TOP grade of the mix, is 3 feet above, the bottom of the box would be about 2'-2'3" above the previous level.) Higher levels would be the greens.

Thanks for any and ALL help! Sorry it's so long!