At least 6' long and at least 2' deep and 2' high. It depends on the size of the rabbits as well. Is it going to be a single or 2-tier hutch. If you are having it made you could have a shelf put in at the bedroom end as rabbits love to sit up on something. A lot of folk are opting for a shed or playhouse, much better protection from the elements and predators.
there 13 weeks old tomorrow, but growing quickly! its a 2 tier one, and hes making it adaptable if i need2 seperate them. i havent got room for a massive playhouse, this seems to be the best option
What breed and size are they?
there english lops
As in English Lops with the really long ears? If you haven't got them yet, you may wish to reconsider getting that breed if you haven't got much space, as they are giants, and need soooo much space.
You'll need a longer than average hutch, and you'll need to get it deeper and higher too. The height is especially important, as they must be able to periscope properly. They'll need lots of space to prevent them getting spinal problems from a lack of exercise. I'm not sure on what the height should be for an English Lop, at least 3ft I would think, I'd edit the title to include 'for English Lops' so that hopefully some owners of them see this and can tell you how tall they are when they periscope.
they cant be lops then. as there ears arent very long. the lady who i got them from says there 'english rabbits'. ive got a pic on here somewere
One of my rabbits is 3.45kg, so this pic will give you some idea of how big he looks in a 6x2x2ft (internal dimensions) hutch, English buns can get bigger. He is just over 2ft long when he lies down properly. It is a bit small really, but I had to buy it in a hurry and so didnt have much choice. If I got one custom made I'd get it 3ft tall and 3ft deep, and I'd have a shelf he could hop up onto in the sleeping area. The idea was that he had 24/7 access to the run, which is 6ft(W)x8ft(L)x2.5ft(H). At the weekends I try to get him out in the garden for free-range, as he loves the extra space.
http://i1081.photobucket.com/albums/j344/Nessa_Roche/SAM_3560.jpg
(note the pic was in summer, he has more hay to keep him cosy now!)