Hi stanlmic
I've just started with 4 (ex-batts) and again have no experience so can't really help on the chicken keeping side.
However, I too built my own house for them and can give a bit of advise on that.
What I'll first say is make sure you have lots of room to get in easily - I opted for a door half the length of the house which I thought would be enough. But in practice (and I've only had the hens for two days) cleaning is quite difficult. So, if you do something like mine, maybe make the door in a little larger, or if it's fairly low down make the roof detachable? (although if they're in the house when you take it off it might frighten them?)
After some research on here, I found that you need to have a perch approx 2"-3" wide allowing for 20cm of space per hen (or more for a larger breed) and have it around 20cm off the ground. I have mine lower at the moment as we have ex-battery hens and so they're not quite as agile.
The nest boxe(s) needs to be dark and raised from the main house - but not as high as the perch as they may sleep here etc instead (and poop)...
I haven't added this yet but need to - a slide out floor - even just some chipboard will do fine - they create a lot of mess and it'll be much easier to just slide out and wipe clean rather than have to scrub the main floor of the hen house by hand (if you have a small door like me then it is quite hard to reach the far corners. Mine poop there too!)
It needs to be raised from the ground too if possible - mine is on some bricks but you may incorporate some legs into the design (part of the frame perhaps)?
They need fresh air, but not drafts - so have a vent with some mesh over it at the top. Make sure it's well sealed because redmite can get in through any gap.
Um, that's all for now I think - feel free to ask more questions. For some photos of my house go to
www.rkins.co.uk/henhouse - it shows it from frame to finished product.
Good luck!