I used zip ties outside on the top plastic netting to cover my run for my escapee game hens and I also use this pen for the teen age babies. I went through 2 super value packages of cheap zip ties from walmart yes like a zillion of them to join and secure the top plastic to wire sides. I live in east texas, hot humid weather, cold weather, rained huge amounts this year, and I have major racoon issues!!! Killed three this year as matter of fact, not one was able to get through the top and that is where they go to first and I don't have hard wire or metal wire underneath the plastic. I covered for hawks and cats mostly. The zips are holding great no deterioration sp? no degrading of them at all and it has been a year and I used cheapy cheapy ones. oh well just my two cents there.