Making your own house can be expensive to i bought a house of Ebay new imported was a lot cheaper than buying the wood to make one
we have 7 hybrid layers and use a Electric net as a Fence the odd one gets out now and again but the fence is there to stop foxes getting in not chickens getting out
even with 36 ft x 30ft of space and the grass starting at 6" high and during a good growing time they have scratched out most of the grass in a few weeks
im probably going to restrict the run a lot more in the winter and might make up some Net and frames to cover areas of the grass to let it grow up and rotate the covers
remember the smaller an area they have the more you need to entertain them etc ours are lucky in that they have a tree to climb and lots of area to scratch about in and make dust baths etc the house is raised up so they have shelter and it also covers the food and i chuck in tree limbs ive cut back and old logs to give more areas to find Grubs and insects etc
I also use Shredded paper as bedding. Chickens produce most of their Poo at night which if you grow your own is a useful stuff when cleaned out it goes on the compsot heap (usually clear out the lumps once a week and add a bit more paper in then a full clean out and replace every 2-3weeks )
gets rid of all the confidential paper work and junk mail
as said you can leave them as long as they have water and food and if you can ensure they are secure from Foxes if you cant shut them in the house at night
I have found the Gold Cockerel books to be good and have a few they arnt expensive the basic one covers several ways of keeping them hosed depending on how much space you have
http://goldcockerelbooks.co.uk/gold/index.php/21st-century-poultry-breeding-1.html
If you buy Ex battery hens etc or even some from Free range systems at 1yr- 2yrs old ish they you wont Lay for several months as they will have entered their moulting cycle (this is why the commercial guys get rid of them its not worth feeding a chicken for 3 mths for no eggs its cheaper to replace them )
ATB
Duncan