Q: What is the purpose of the one-by's I see under all the floor and ceiling joists on the show? Do you think this is a better insulation for the sheet rock, and do you also do it with roof trusses?

– Joe, Bordentown, New Jersey

A: Tom Silva replies: It's actually an old building practice that we continue to use. And it's a method that is used mainly in the New England area, certainly a lot more than it is in other parts of the country. If you open up an old house here that's 100 or 150 years old — even older — you will see it in the ceilings. We use 1x3 spruce strapping and run them under the ceiling perpendicular to the floor joists. The purpose it serves is that it helps share the weight load. A further benefit is that it gives the electrician a place to run wires without drilling holes, and, in some cases, also enables the plumber to run small pipes under a ceiling.

The one-by's also are a way of leveling. If there are any irregularities in the dimension of the lumber, you can shim different sections underneath with strapping.

As to your other question about roofs, the answer is yes, we do use strapping with roof trusses. I think it's a better insulation for the sheet rock and it allows the electrician to run his wires perpendicular to the joist or the truss without having to drill holes. And it does add some structural integrity to the floor or roof above as well.
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