Grass area formula

I have less fencing than I thought so my total enclosure is now going to be 10m by 14m. In the middle is a concrete slab for the house which is 2.5m by 2m. If I have 6 hens and want to try to keep it green do I divide it in to 4 or 2 ?

That's my worry and I really don't want it to just be a dust bowl. I could let them out when I'm home I suppose but the garden is large and I can't be sure to see them all the time. They could also wander off into the fields or the lane.

The house is pn 18" legs. will they have enough intelligence to go under it?

height should be fine, but if using alternate areas the house in the middle could be a problem. Could you site it in one corner with a roof over to keep an area dry and "gate" the grass areas from this. i.e think or 3 rectangles, 1 horizontal and 2 verticals side by side underneath.

I have got old plastic garden tables from Freecycle and reduced the height of the legs if necessary and  my chooks also use these for shade and shelter. Also have planted fruit trees which are starting to offer some shade.

It is probably a case of trial and error. What works for one garden/set of chooks may not be right for another