guaranteed, rats, racoons or any sort of weasle type critter can get right through, pretty much any type of all poly or all plastic mesh, i would suggest instead a galvanized vynil coated hardware cloth like the , the 1/2" mesh pictured in this photo, it is designed to keep critters out , i would also recomend avoiding uncoated galvanized hardware cloth as it is coverd in zinc which is toxic in moderate quantities, and subject to osmotic absorbtion [absorbtion through the skin, (especially when wet )] that also makes it bad to drink water that has been in contact with the wire, the vynil coated wire (in my picture) is coated in pvc (polyvynilchloride), which is also toxic and subject to osmotic absorbtion (especially when wet ) in either case crawling on, or drinking from the wire should be discouraged (which is possible with the right design considerations), the black plastic mesh you have pictured is most likely PE (polyethelene) which is relatively non toxic (even when wet , and far less subject to osmotic absobtion than the other two , but it wont keep out chewing critters that are determined to get in ,. one option would be to cover the outside of the frame with the vynil coated wire (to keep critters out ) and cover the inside of the frame with non toxic black pe plastic mesh for your critters to crawl on, however that requires twice the material and substailly increases the cost (the vynil coated hardware cloth is about $15-20 for 3x8' piece) of course there is another problem free option , that would be welded stainless (304 not 316 ) 1/2" wire mesh, or available in almost any mesh size, but the cost is prohibitive , about $7-9 sq ft + shipping, but it is problem free, other than cost.plus the cost of any of these materials can be substantially reduced by buying it in bulk rolls usually 100'/ chicken wire is also galvanized (zinc coated) and rats can get through anything larger than 5/8" mesh (like chicken wire)so 1/2"mesh size would be my max recomended mesh size. the place to go for all things wire mesh (including generall information) is;
http://www.twpinc.com/ feel free to repost or pm if you have any specific plastic or wire mesh questions ps i know there are going to be all kinds of people telling me how they have not had any problems with outdoor enclosures using plastic or galvanized mesh , but that doesnt change the facts, a person could get lucky , or they could go all season with no problems , and come home one day to find out the hard way, so the no problem argument is just an accident/problem waiting to happen in my book.
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