Wood – How to use to replace extra thick (1.75″) sill plate? Should I shim 2x dimensional lumber

foundationframingrepairwood

My house was built in 1956 and I have come across some sections of sill plate on the cinder block foundation wall that need to be replaced due to termite damage or rot. It seems that they used some extra beefy lumber, and it measures 1.75" thick.

I understand the basics of how to replace the plate, by jacking up the floor joists, etc. However, what would you suggest I do about making up the extra 1/4" compared to a modern 2x lumber?

Some options I thought of:

  1. Custom order lumber
  2. Rip 4x stock to size
  3. Shim with:

    • Rip 1/4" redwood shims
    • 1/4" ply
    • 2 pieces of 1/8" Redwood Benderboard
    • 2 pieces of 1/8" Masonite
    • 1 piece of 3/16" Masonite and ignore the extra 16th
  4. Just ignore it? Seems like a lot to ignore.

  5. What options am I not thinking about?

Thank you for any advice.

Best Answer

You can go two ways with it. You can purchase a 4X6 or possibly a 3X6 and have it ripped to the 1 3/4" thickness you need, presuming the original is close to 5-6" wide. Or you could get the standard 2X6 and use non shrink grout to tuck under the plate after it is shimmed up in places to allow the grout to go in the areas that are the most important, under the joists. In either case the material need to be pressure treated since you have termites present in the area.

An added third way, you could even shim the joists with the sill plate tight on the block with no grout and use wood shims. Pleas please do not use masonite, it is terrible for shim stock.

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