Electrical boxes, including switch boxes, are usually 3″ x 5″ holes in the walls. When these boxes are in exterior walls, they need to be ‘air sealed’ to prevent outdoor air from circulating in the wall assembly or into the home. How are professional remodelers sealing around electrical boxes? During new construction, homes or renovation, spray foam is often used:
After the drywall is installed the boxes are caulked.
How do you seal the electrical box in an existing exterior wall? The box can be caulked as shown above or a foam gasket can be used as shown here:
If you have any questions about sealing around electrical boxes or about other general building topics please feel free to drop me a note at firstname.lastname@example.org