I am in the preliminary phases of a new home design, which I will eventually get run by a professional builder but I am conceptualizing it on my own.

So I am exploring different ways to attach the first floor wood framing onto a cinder block foundation. The basement will be fully finished and have a legal ceiling height. About 60% of it will be below grade and the rest above. The location is on a high elevation in Colorado, countryside.

What are some different ways to set the joists on top of a cinder block foundation. The foundation perimeter is approximately 18' x 52'/ Preferably with pictures.


IMO, there is no other option than using a sill plate:

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  • thanks. why would you use I-joists vs regular 2x lumber? and how are the sill plates affixed to the cider blocks?
    – amphibient
    Apr 22 '15 at 21:52
  • 1
    @amphibient Engineered lumber will let you do larger open spans, unsupported. See TX's answer for affixing to cinder blocks. I've only dealt with concrete foundations where the crew has already embedded foundation bolts for this purpose.
    – Mazura
    Apr 22 '15 at 22:59

Pick locations for foundation anchor bolts (usually 48" apart), then fill in those holes in the cinderblocks with mortar, and set the bolts in the wet mortar. Keep the bolts toward the inside of the wall. Then place a metal sill gasket / termite guard over the cinderblocks / bolts, then adhesive and a sill plate, with holes drilled for the bolts.

Tighten the bolts down with a washer and nut. Then run a foam foundation gasket, then rim joist up on edge around the foundations and start hanging floor joists.

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