I notice that vents used on roof, in sheds, and also for crawl spaces seem to be rather big in the mesh screen hole size, not fine small hole mesh like screen doors and windows. At least that's from what I see visiting homes in my area, see on my own house, and on sheds sold at Home Depot.
I would think the larger hole sizes of the somehat sturdier mesh would allow insects and pests into shed/roof/attic/crawlspace. Is it desirable or some reasoning to using that type of mesh over a fine screened mesh in these areas? I figure you could better mitigate drywood termite infestation this way in terms of minimizing gaps the swarmers can fly into.
Rodents climb up house walls to gain entry at eaves through ventilation holes. 1/4" is sturdy hardware cloth, stops most as some mice can go through that size hole. Hard to gnaw through it, unlike screen door screen.
Code: "R806.1 Ventilation required.
Enclosed attics and enclosed rafter spaces formed where ceilings are applied directly to the underside of roof rafters shall have cross ventilation for each separate space by ventilating openings protected against the entrance of rain or snow. Ventilating openings shall be provided with corrosion-resistant wire mesh, with 1/8 inch (3.2 mm) minimum to ¼ inch (6.4 mm) maximum openings." From: http://publicecodes.cyberregs.com/ic...3_8_par071.htm