T&G Flooring repair challenge: Alignment of T&G's?

[Bradley Potts]

Hi there, I've got a tough restoration challenge with some Doug Fir T&G porch flooring: The original boards are 13/16" thick X 2-1/4" wide, new stuff is 5/32" thinner X 3-1/8" wide. I was aware of the width issue and am prepared to re-mill to the correct width, but the thickness difference is not so easily overcome, not that re-milling should be considered a quick and easy project.

At this point, even though I just bought and cut down those too thin boards (no returns now), I think I may be looking at having to custom order the right stuff at considerable additional cost. Does anyone have a better idea?


TIA, Bradley

[Wayne Lomman]

Install a correct thickness packer on top of the joists and modify the tongue/groove where it meets the old flooring. The packer needs to be robust material. A strip of polyethylene or nylon is best as it won't compress and won't fall apart with use. Make sure it is the full width of the top of the joist. Fix it firmly to avoid squeaks. This happens all the time when repairing old floors. Cheers

[Scott T Smith]

If you start with lumber you can buy T&G profile cutters to cut the sides.

Or - if you keep your existing flooring boards simply glue some veneer onto the bottom side of the planks to make up the thickness difference (assuming the T&G's line up).

[Steve Rozmiarek]

Like Scott said, veneer makes good shim backer. Drywall shims work ok to. I keep a jobsite tablesaw handy when I'm patching new floor into an old just to move the t/g as needed.

[Bradley Potts]

Hey, thanks for the replies. I should have mentioned this, but it seems you probably already figured it out. There is no subfloor, as this is on a porch, and I am concerned that the modern, thinner floor boards will be over spanned for their thickness and reduced grain quality. Should I be concerned about that?

[Jim Morgan]

At just a little over 5/8", your stock does seem flimsy (when I redid my porch last year, I used 5/4 meranti). What kinds of spans are you talking about?

Also, what kind of weather exposure is there? T&G flooring isn't the best for allowing water to drain...

[rudy de haas]

SInce your boards are a bit thin you might want to consider getting something like a hickory (or other hardwood) beam you can cut into 1/8th x 2.5" strips. Properly glued to bottom side of your boards these will be protected from most of the weather and add a lot of strength while reducing expansion and contraction issues. You can then mill (shaper? I assume..) the T&G on the new combined boards to whatever height works.

[Scott T Smith]

Brad, unless you have 12” joist spacing I personally wouldn’t go thinner than 1” on the flooring, and 5/4 would be preferred.

I’m presuming that your 13/16” original boards might have been sanded once or twice.

[Bradley Potts]

Sorry, but work got in the way so I drifted off the thread.

The joist spans are the usual 16" o.c., and the porch is well covered (i.e., water comes from cleaning or errant sprinklers), but nevertheless here in California, Doug Fir is the typical material of choice for this application.

Based on my experience and intuition, and your comments, I will use the 13/16" stock...now to do a trial run in order to decide if I fab the boards or pay a moulding shop to do so for a fee.