Hello,
In my under house storage area there is an opening (roughly 66cm x 82cm) like a window, but with no glass in it. The metal bars are cemented in, but the mesh you can see in the photo is just a loose piece that the previous owner attached using zip ties. The large apertures in the mesh and the way it is currently secured means there is no protection from pests. The area around the window on the inside is quite rough because the cement was not smoothed down. The house is on a slope, so on the other side of this window is soil, going up to the bottom of this window opening (I will dig this soil away so it sits at least 10-15cm below the hole). The house sits on sandstone, so is prone to moisture coming through the rock.



I would like to cover the window opening in some way so the storage area is protected from pests and vermin, but try to maintain some ventilation because of the sandstone.
I was thinking of using some kind of mesh, perhaps in a frame, but wasn't sure how I could attach this securely to the brick/cement around. Then seal up the edges using some silicone or sealant, especially where the mesh/frame can't quite sit flush to the wall because of the rough surface.
Would this stainless steel insect screen be suitable?
https://www.bunnings.com.au/syneco-810mm-x-2-05m-stainless-steel-insect-screen_p4110616
I'm worried this might not be strong enough to keep out mice/rats though, so should I have a layer of netting as well as the insect screen? Bunnings sells mouse mesh with an aperture of 6.5mm.
https://www.bunnings.com.au/jack-900mm-x-5m-6-5-x-6-5mm-mouse-mesh_p3040081
Is there a stainless steel alternative? I imagine it would be difficult to change out the mesh in a couple of years time, so I would prefer something which doesn't rust and has no need for maintenance.
How might I attach these securely to the wall?
Any advice would be appreciated! Thank you.