A roofing question???

you can use it just as it is with wire to keep out mice and rats etc. The venting will be above the height of your girls heads which is just as recommended, plus less places for red mites to hide 

I agree with Joy Bogof!!!

thats not very nice telling him to bogof grannie

 Buy One Get One Free.

Onduline is brilliant if used properly!  Like everything else.

Here is their fixing guide, if it comes up okay, and a pic of one of our roofs!

http://www.ondulinebuildingproducts.net/Onduline%20Fixing%20Guide%20Grey.pdf

Well on the shed that Joy gave us with an onduline roof, it had a good foot to 18 inches overhang!!!  They wanted to shield the chooks from the rain a bit, but on the house in the photo, we only have a small 4 - 6 inches because we want to put guttering under it when we can!

An overhang won't have much weight put on it will it?  But you'd have to think about will it get a load of snow on it anytime, or what are the winds like where you are?  In Lincolnshire, we get a lot of wind, so big overhangs are not good!