Create a greenhouse

So have modified an area in my back yard to do square foot gardening, it has a structure to it that I can build off

Having some local bird issues, I live opposite a park which has a large amount of wild birds, parrots, cockatoos, magpies, crows you name it

Was going to put some bird netting up, but was th8nking why not seal it.

I have found a supplier of plastic corrugated sheets, but not sure which is best to use

Here is a photo of their products

Remember that if you create a greenhouse effect to protect the plants from birds, instead of using netting, you will have to deal with the heat build up in those mini-greenhouses.  They must be adequately ventilated without creating openings for the birds to enter.

OG is correct. Using clear plastic can create a really hot house and needs careful venting to get rid of the killer heat. Strong recommendation not to do it!

I don't know what you mean by building off of an existing building, unless the garden area is on the south or east side of the building and you want to attach a frame to the building and put the beds inside. The material to cover the whole frame depends on what you are trying to keep out. If it's birds, chicken wire or 1/2" hardware cloth will keep out all birds but allow in pollinators.

The cheap black bird netting sold in big box stores can be dangerous to wild life getting caught and injured, or even dying if not carefully extracted. They simply don't see it until it's too late. I have some cordon fruit trees and bought this green netting that is thicker and easier to see. I'm hoping it works safely and next summer will be the test.

https://www.americannettings.com/shop/

PS: have you read the 2nd or 3rd edition of ALL NEW Square Foot Gardening? I can't remember.

What I meant with existing frame, is the patio tube that is already there, i want to stop birds, but then thought I could semi close it in to allow longer growing periods, we do not get the frosts like you guys do.

Will drop some clear sheets on the top and bird netting on the sides