As you can see Above the monster is nearing completion. For scale, the center support is where the end of one of the normal hutches would be. I neglected to get a photo of the basic frame of the hutch before I added any legs, but Right shows you basically what it looks like. It is an 8' by 3' frame of 2x4s with two interior supports at 18" in each. The wire is secured to the frame from below with a combination of staples and scrap blocks of wood nailed in at strategic locations.
On the Left the photo shows the blocks positioned about every 8 inches with staples holding the wire tight everywhere else. Ideally, we would have the entire frame edge lined with 2x2s or 1x2s to provide the absolute best way of securing the wire from below. The reason I decided to secure the wire from below is to avoid the cleaning issue of having urine and feces caked on the wood that is obscured by the wire. So far that has worked out fairly well with the addition of the blocks since staples alone eventually fail.
The center strut is unsurprisingly a vital part of keeping the growing out hutch stable, and for giving it a long lifespan. As you can see, it is actually a very simple structural piece. The nice part about using 2x4s for everything is I have lots of little leftover scraps. The chunks of wood left over from cutting the 45 degree angles are going to be used to support and connect the two parts of the corner legs to keep them solid and stable as one unit. This should decrease the stress on the hutch, and make the doors easier to work with. The lack of side to side stability in the original hutch design coming from only having the single direction of leg has been a pain, and the legs on this are designed to attempt to ameliorate that particular difficulty.
The next major difference in design from the smaller hutches is the roof. On a 4' roof you can deal with fairly minimal bracing. For an 8' roof on the other hand, you can not. Especially when you are using old warped plywood. To keep the roof from sagging in the center, or breaking under the weight of the snow in winter I designed in a lot of cross supports. I can't claim that all of the supports you see Right and Below Right are carefully measured to the best possible positioning.
Fortunately, a good friend of ours came up while I was in process last Friday and gave a hand. Trying to put the roof in place would have been nigh on impossible without a second pair of hands. He isn't in any of the photos because I'm not sure if he is ok with his face being on the blog. In most of these photos he is just off to the side, or on the other side of the hutch providing the second set of hands needed to do things correctly. Left you can see me trying to line up the corners of the ply wood. Due to the warping combined with the lack of level ground, to get it properly squared required quite a lot of force. The way we achieved this without a saw or a fresh sheet of plywood was to go corner by corner.
Get one corner tacked down with a nail, move to the diagonally opposite corner and tack that down. Once those two are in and solid, getting the rest is actually much easier. Once all four corners are down, we went ahead and nailed the warped wood in to a number of the support members. As you can see Left we eventually got the roof fairly well flat all things considered.
The thing to note is the drastic weight increase drop in the hot days. I expect to see virtually zero weight gain in the next few days due to the sweltering heat and high humidity. The rabbits aren't eating or drinking at all during the day, but when I return in the morning the food is entirely gone. I wonder if cold ends up producing the same sort of slow down of weight gain, or if this is just a coincidence with the litters naturally slowing down as it gets hot.
Dawn's Litter Weight Chart
Sunny's Litter Weight Chart