Hi all you incredibly helpful people

. Im wondering if any of you can help me regarding welded mesh for a hen ark. I am getting an ark made, mainly for when i am away or going to be home late at night so I can leave my free rangers inside for the day. Normally i shut them in at night so they dont get killed by ferrets or stoats, but the hutch i have is no good other than for over night. This is for my four wee rescue roosters who have to be seperate from the main flock. Yes I know you will think i am mad, but they are dear wee boys and deserve to be safe!
I live next to forestry where there are stoats and ferrets. The man who is making it uses 19x19mm welded mesh (18mm square hole), in the past I have always used 11x11mm (10x10 square hole). This is his business, and he always uses the larger size, but he said he is not sure if stoats can get through it or not. And most people dont seem to be too worried. Does anybody know? I dont want to provide a stoat with a captive dinner- obviously the whole reason im getting a good ark made. Ive looked in the poultry info and cant find anything, and also tried the internet but the sites with the info woudnt open.

Thanks.