# Wood expansion question



## OutdoorSeeker (Jul 13, 2015)

If I took some oak hardwood and planed it down and routed my own tongue and groove, what would I need to consider for the movement.

This would be 3/4 x 38” x 8” wide planks.
Installed vertically along an 18’ wall for accent.

I have read about finishing both sides of each plank to help with swelling.

What do I need to do for proper installment and spacing?


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## Tennessee Tim (Dec 15, 2010)

OutdoorSeeker said:


> If I took some oak hardwood and planed it down and routed my own tongue and groove, what would I need to consider for the movement.
> 
> This would be 3/4 x 38” x 8” wide planks.
> Installed vertically along an 18’ wall for accent.
> ...


MAJOR moisture control !!!!! 18' can be a lot of movement!!!! If you'll notice a lot of the large wood wall expanses are individual panels to accomodate for the huge possible movements, that can be positive or negative/swell or shrink.

You need to know starting where the wood MC is and what the average room MC is....the 2nd is harder to judge/know. You can incorparate into your design every 2-3 ' a expansion accomodater (longer tongue and deeper groove) for excess movement that OR just build all the T&G boards that way and allow a slight more install room per board. IF you'll notice the newer/modern T&G in past 50 years is getting lesser /shorter to save lumber which equals $$$ in long term for manufacture BUT makes it tougher to accomodate much movement.

A lap joint may be a option to get a slightly larger overlap for precation and have the same basic one side view.

Yes at least seal the back side...this doesn't stop movement ,it slows the change to more balanced pace on both sides which keeps the boards flatter....hardwood flooring has the vapor barrier to accomodate the unfinished side as a finish/balanced proportion.

Maybe this will help.


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## OutdoorSeeker (Jul 13, 2015)

Tim I assume this is what your getting at? That would be a lot easier to do.

I tried to talk my wife into a panel type of wainscot, but she really wants the Knotty pine(wide plank) look. So since I have some oak drying in the garage I thought we might go with it.


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## OutdoorSeeker (Jul 13, 2015)

This is what she wants but does not want the "Styles" that would hide seams if I used a panel board material.


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## Steve Neul (Sep 2, 2011)

OutdoorSeeker said:


> If I took some oak hardwood and planed it down and routed my own tongue and groove, what would I need to consider for the movement.
> 
> This would be 3/4 x 38” x 8” wide planks.
> Installed vertically along an 18’ wall for accent.
> ...


Over time your biggest problem will be the wood shrinking but that should be minor in most cases. It would be helpful if you knew the moisture content of the wood going into the project. If the wood was very dry and you installed it raw wood and the weather got very humid before you put a finish on it then it might buckle. If you prefinished the wood on both sides and then put it in the house for at least a week and let it accumulate to the house before you installed it you should be alright.


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## OutdoorSeeker (Jul 13, 2015)

I will try to get a MC reading this week Steve.

I just planned my first Hickory 2” thick board this weekend. That lumber has been sitting in my garage for 4+ years and reads 10%. Not sure where the oak sits on MC.


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