What kind of mesh roll should you use to screen soffit vents?

Comparing mesh types

• Galvanized hardware cloth, 1/8 inch: inexpensive, stiff, holds its shape. Cut edges can rust over time in humid Georgia air.
• Stainless steel mesh: costs more but lasts and resists chewing best.
• Aluminum insect screen: soft and easy to work, but squirrels go right through it, and its openings are finer than the code minimum for vents.
• Fiberglass screen: the cheapest and weakest option; it also traps pollen and lint.
• 1/4 inch hardware cloth: more airflow but at the upper limit of the code range, and small wasps can get through.

Installing it on wood soffits

Older Georgia homes with plywood soffits often have rectangular cut-outs or round holes covered by louvered vents. Remove the vent cover, cut the mesh an inch or so larger than the opening on every side, staple it to the back from the attic if you can reach or to the face from below, and reinstall the cover over it. Use stainless or galvanized staples and keep the mesh flat so it does not sag into the opening.

Watch the airflow

Every layer of mesh reduces net free area. If you add screen behind every existing vent, total intake may drop below what the attic exhaust needs. In that case, add vents or switch to continuous strip vents, which spread intake along the whole eave. Also check that insulation is not packed against the back of the vent, since new mesh does nothing for a bay that is already blocked from inside.

The intake and exhaust balance is explained in roof ventilation basics.