I started by collecting some spare parts and recycled doors. I got eight sliding commercial doors from a grocery store renovation, caution these are heavy, I just about squashed myself moving one of these. I also found some single pane glass removed from a local bank. These few things form the bulk of the materials for the sunroom as I chose a location with an existing roof. The rest of the wood was leftover from my recycled $150 deck project, along with a roll of R11 insulation and some wiring, breakers and a small heater from a house that was burned by the fire dept. I bought 1 piece of polystyrene foam board insulation for the end walls a roll of black duct tape to seal the doors together and some foam rope for the big gaps, total spent about $34.
Now that I had all my materials together, it was time to start. Since my covered porch has concrete for the floor I started with a piece of pressure treated 2x4 for the sill, drilled and anchored around the perimeter of the sunroom. Then I measured the difference between the top of the sill and the bottom of the rafters, in my case the difference was about 2 1/2" more than the height of my doors, so I screwed a 2x4 along the bottom of the rafters, then cut an angle along the second 2x4 starting at nothing on the edge of the board and down to ½ " in the center, this left a nice lip to butt the doors against on the outside. After these boards were in place I started placing the recycled doors along the edge, I put four doors down the long side of the new sunroom, most of these had weather stripping in between, but the black duct tape provides a nice seal and is almost invisible on the black door frames. After finishing the long wall I was ready for the end walls. For this I used a door on each end and filled the space left by building frames from recycled decking for the single pane glass from the bank. One of these I put hinges on and use for the entry door. With the end walls in place I still needed to fill in the top portion, this is where the polystyrene panel comes in , I bought the 2"x2'x8' foam board, cut diagonally this one piece is enough for both ends. Some more black duct tape to seal the edge to the top of the wall, and the sunroom is enclosed. And just in time it froze two days later.
With no supplemental heat the sunroom absorbed enough energy in the day to stay about 45 thru a couple freezing nights, which is great, but I wanted a backup heater just in case we had no sun for a few days. I had in my recycle pile a wall heater some wiring and a couple breakers from a house that had been scheduled for a practice burn. I ran the wiring around to the electrical panel popped in the breakers and hooked up the heater. I dialed the thermostat down so it only kicks on at 40 deg or less to keep the electric bill to a minimum. That said those of you with no experience hooking up wiring, get somebody who knows how to do it to help, there is enough juice in your electrical panel to KILL you. There are lots of books out there as well on this subject, and the folks at your local home improvement store can give you some tips. But once again DO NOT open the panel if you have no idea what you are doing. Get a small plug in heater and run an extension cord. With a south facing sunroom you should only need supplemental heat after days with no sun. I placed a 55 gallon drum filled with water inside to provide extra mass to absorb as much winter sun as possible, each gallon of water can store 8.5 btu's per degree of difference. That means if the temp in the water barrel gets to 65 your barrel will release 15,000 btu's before it gets to freezing. If you've got the space more is better. I also installed the left over R-11 insulation in the rafter spaces to limit the flow of heat out the roof.
So far this sunroom on a budget has worked very well, my plants are happy and kept from freezing and not taking up the whole house. In another month or two I will put some flats of veggie starts in to get a jump start on the season, and with the cooler temps I shouldn't have the leggy tomatoes that I got last year in the house. All in all a pretty easy project and very worthwhile, my only regret..... I haven't found any more doors to enlarge my sunroom to use the whole porch.
Geraniums still blooming in mid december. Happy recycling Caleb