How can I replace or repair termite damaged 2 x 6 tongue and groove sub flooring without altering the 1 x 6 hardwood floor on top of it? The hardwood floor runs perpendicular to subfloor, and all of the damage is done between the floor joists. It still feels sturdy when you walk onit, but I want to reinforce or replace the subfloor.

1 Answer 1


i dont think it can be done. the hardwood has to be nailed to the subfloor, and removing the subfloor from below would make it release the flooring. on top of that, the stiffness of the floor is partially due to the connection between joists that the subfloor creates. if you somehow removed the subfloor, putting it back would require small enough pieces to fit between the joists, which would substantially weaken the floor as the joists would not be connected any longer by the subfloor.

you could certainly reinforce it by adding sections of spruce plywood, and gluing them up against the subfloor from below. use a good quality construction adhesive and then push it up from below with solid lumber blocking screwed laterally into the joists

  • I agree I have never seen it done
    – Ed Beal
    Sep 1, 2016 at 0:38
  • I have scraped the damaged subfloor (there are about 7 total, spread out over a 6 foot by 4 foot area. 1 spot on a board went to the bottom of 1 hardwood board) and some boards are have decent amount of damage. Should I put that hardening (epoxy?) filler in the subfloor or do you think the reinforced spruce plywood is good enough. Also, should I treat boards with Tim-bor or creosote or something? Thank you so much... 1st time user...how can I reward you?
    – Ed D.
    Sep 1, 2016 at 20:10
  • assuming that the termites are gone and that problem permanently solved, i would spray zinc borate over any affected and adjacent areas. simple construction adhesive should work fine, but if you are filling any larger voids 1/4" or larger, get some good quality polymer modified tile mortar and use that in place of the adhesive. it will fill the voids and act as a supporting grout between the old rotten floor and the new spruce reinforcement Sep 2, 2016 at 2:27
  • this is a public help forum. no rewards desired or required. the honour is to serve Sep 2, 2016 at 2:28
  • since I am a novice DIY, I really appreciate your help and patience! Since I last posted I have noticed a good amount of "give" in one area of the hardwood floor and my voids are about half (3")of the subfloor in certain areas. The termites are long gone. But my crawl space hole will only fit about 2'-6" strips of plywood. So, if I may clarify:
    – Ed D.
    Sep 2, 2016 at 17:43

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