Tongue and Groove over 6" wide - need advice on best way to keep them from cupping/moving

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Forum topic by woodengaragedoorguy posted 610 days ago 1222 views 0 times favorited 8 replies Add to Favorites Watch
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7 posts in 641 days

610 days ago

I put a nice sized bead of exterior wood glue to the garage door frame, trowel it, then apply tongue and groove material piece after piece. I use 1-1/4” divergent staples which work great for holding power. Most of the tongue and groove lays pretty flat to the garage door frame but I have noticed that when I start using tongue and groove wider than 6” I sometimes see that material cupping slightly. Note* these materials are glued up with 2 glue lines (3 pcs total making that one piece of TGV). I know I could screw the center of each piece and then use a wood plug to fill then sand smooth. But does anyone have any tips on a type of glue, or fastener method to where I could get these materials flush and have less cupping? All wood that I use is below 10%.
Thank you,

8 replies so far

View Tyler's profile


52 posts in 646 days

#1 posted 610 days ago

you could try putting a type of backer board or furring strip and attach it.

-- You can get alot further with a kind word and a hand gun, than just a kind word alone

View Don W's profile

Don W

14891 posts in 1202 days

#2 posted 610 days ago

I wonder if its cupping because its glued to tight? Wood needs to move, and your not going to stop it short of some sort of permanent seal. The reason for tongue and groove is to allow for the expansion and contraction. That’s why smaller pieces don’t cup, there is enough joints to allow for the movement.

Try incorporating some sort of break, like a seam. Use a tenon type piece maybe and let it slide.

-- Master hand plane hoarder. -

View bondogaposis's profile


2495 posts in 985 days

#3 posted 610 days ago

Using quarter sawn material will prevent cupping. Flat sawn will always want to cup to some degree. You really can’t stop it other than using a stable material like plywood.

-- Bondo Gaposis

View Bernie's profile


414 posts in 1471 days

#4 posted 610 days ago

I’m thinking along the same line as Don and Bondo. Too much pressure on the clamps will cause cupping and the other issue of wood movement, especially on a garage door but you probably know this already since your statement of “all wood is 10%”.

There is one adhesive you might want to try. I was introduced to it by my wood working guru who claims this stuff will not turn hard, yet it holds better then wood glue. It’s called “LOCTITE”

-- Bernie: It never gets hot or cold in New Hampshire, just seasonal!

View joeyinsouthaustin's profile


1246 posts in 707 days

#5 posted 609 days ago

We run into this problem with exterior siding. One side in sun and humidity, one in shade. Do the pieces have any kind of back cut?? (like flooring) this can relieve the pressure on the front side. Also, when we have milled ourselves, we always try to install with the natural cup crowned to the shade side. That way it will tend to flatten when warmed on one side only. +1 on leaving room for expansion. also +1 Bernie In glued applications like this, we use a urethane glue, like flooring, or PL. It will allow for movement.

-- Who is John Galt?

View MonteCristo's profile


2095 posts in 822 days

#6 posted 609 days ago

Wood moves. Especially in an exterior situation, where humidity and temperature swing a lot more. Try and glue or screw it to stop the movement and it will likely split.

-- Dwight - "Free legal advice available - contact Dewey, Cheetam & Howe""

View Bernie's profile


414 posts in 1471 days

#7 posted 609 days ago

Hey Joe – just went down to the workshop and the LOCTITE I mentioned is a urethane glue used in flooring and “PL” is on the tube. From what you are saying, my guru is right as usual. It’s been about 6 months since I first used it and no problem thus far… with your comment, I’m in the relax mode now… thanks!

-- Bernie: It never gets hot or cold in New Hampshire, just seasonal!

View pintodeluxe's profile


3335 posts in 1447 days

#8 posted 609 days ago

Maybe a picture or two would make it easier for us to help you.

-- Willie, Washington "If You Choose Not To Decide, You Still Have Made a Choice" - Rush

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