Repairing A Severely Rotted Subfloor
After marking the floor plate with a square, our carpenter Chad cut it with a reciprocating saw so the bad section could be replaced and so the subfloor underneath could be removed.
He used a reciprocating saw with a bi-metal blade to cut through the nails where the studs were connected to the plate.
He cut the plate up into sections for removal because this plumbing wall had lots of pipes to work around.
After removing all of the affected wood, Chad made up a strong bleach solution in a spray bottle to kill any remaining mold or fungi.
He measured and marked out a 4×8 sheet of plywood to replace the damaged subfloor.
He snapped a chalk line to connect the layout marks, which were centered over a floor joist.
Following the cutline on the subfloor, Chad used a cat’s paw bar to pull all nails that might be hit with the circular saw blade.
After removing all of the nails along the cut line, he set the blade depth on the circular saw to cut about 1/16 inch deeper than the shiplap subfloor before cutting along the line.
He removed the subfloor out to the floor joist beyond the damaged area.
A shop vac helps to clean out sawdust and other debris in the area under the subfloor.
Chad placed a pressure-treated 2×6 scab along one of the damaged floor joists to add strength and to provide a solid fastening area. The scab also provides more area for the new subfloor joints.
He nailed the scab to the existing joist with nails approved by the manufacturer of the treated wood, which has specific fastener requirements.
Chad positioned the subfloor plywood to go under the wall so he could lay out notches for the pipes in the wall.
After cutting the notches for the pipes, he positioned the new under-wall subfloor piece to reach the floor joist scab and to leave enough room for the full sheet of plywood subflooring.