Remove the old rotten mudsill and cut new pieces of pressure-treated lumber to replace them. You may have to cut slots in them to fit over the bolts in the top of the foundation. Put construction adhesive on top of the foundation and drive the new mudsill piece in place.

Can you replace rotten floor joists?

Dry rot and termites can compromise the structural integrity of foundation joists. In cases where a joist is intact, it's possible to sister a new joist alongside with construction adhesive and lag bolts. However, when a joist loses structural support, it has to be removed and replaced.

How much does it cost to replace a rotted sill?

The sill plate is the piece directly on top of your concrete foundation, and it has to be replaced if faulty. To replace the sill plate, jacks are installed to temporarily hold up the floor joists, until the damage sill is removed and replaced. Costs for sill plate repairs are $100-$110 per linear foot.