# Plywood Drawers Warping



## cabinetbuilding (Jan 9, 2016)

Hi,

I'm looking at making some drawers out of 12mm thick plywood.
- these plywood boards will be veneered
- BB Grade Baltic Birch
- (see attached example diagram pulled from internet)

My concern is warping/ deforming of the drawer (+ furniture).

I've had a chat with the guy veneering it. He says 18mm doesn't really warp even a few years down the line.
- However apparently 12mm tends to warp noticeably.

1. Now I'd like to use 12mm for the drawer carcass (interior). I'm just wondering - will it warp once joined up?
- biscuit joins for sides

2. Would 12mm plywood be ok for shelves?
- i.e. no warping?
- floating on 4 shelf supports
- span of approx 560mm

Any tips/ comments appreciated


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## TerryQ (Apr 8, 2014)

cabinetbuilding said:


> Hi, I'm looking at making some drawers out of 12mm thick plywood. - these plywood boards will be veneered - BB Grade Baltic Birch - (see attached example diagram pulled from internet)
> 
> My concern is warping/ deforming of the drawer (+ furniture). I've had a chat with the guy veneering it. He says 18mm doesn't really warp even a few years down the line. However 12mm tends to warp noticeably. Now I'd like to use 12mm for the drawer carcass (interior). I'm just wondering - will it warp once joined up? - biscuit joins for sides Any tips/ comments appreciated


First, I make almost all my drawers out of 1/2 inch (12mm) hardwood and have never had warping problems. I would think 12 mm Baltic birch would be ok except for really large drawers. I assume you aren't using drawer slides because the drawer slide would keep it from warping. Also, if you use plywood or other man made product for the drawer bottom you could glue it in and that would help stiffen the drawer.

Second, why do you want to veneer the drawer box? It isn't seen except when open. If you are really concerned about the way the drawer looks when open then why not use hardwoods and show off your joinery with dovetails or box joints?

I like using light colored woods for my drawers since it helps items stick out better so I wouldn't mind the look of a clear finish on Baltic birch.

Not sure 12mm drawer boxes would be a good application for biscuits. It would require extremely small biscuits to keep from exiting the back of the 12mm plywood. There are easy interlocking joints you can make using a table saw or router table.


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## Jig_saw (May 17, 2015)

There should be no problem of warping with 12mm plywood. The only change I can suggest in your drawing is to inset the back of the drawer by about 1-1/2". It will increase the torsional stiffness and also prevent any warping.


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## Oneal-Woodworking (Apr 14, 2013)

TerryQ said:


> First, I make almost all my drawers out of 1/2 inch (12mm) hardwood and have never had warping problems. I would think 12 mm Baltic birch would be ok except for really large drawers. I assume you aren't using drawer slides because the drawer slide would keep it from warping. Also, if you use plywood or other man made product for the drawer bottom you could glue it in and that would help stiffen the drawer.
> 
> Second, why do you want to veneer the drawer box? It isn't seen except when open. If you are really concerned about the way the drawer looks when open then why not use hardwoods and show off your joinery with dovetails or box joints?
> 
> ...


Thought this was an excellent post...


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## GeorgeC (Jul 30, 2008)

OnealWoodworking said:


> Thought this was an excellent post...


I agree totally!!!!

George


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## cabinetbuilding (Jan 9, 2016)

Terry, reassuring to know that you haven't had any issues with warping on your 12mm drawers.
The veneer is just for the overall design style of the furniture piece.

Thanks for the tip on the biscuit join. Box joins sound like a better idea.
- (going for a clean look at the corners so prefer to avoid dovetail. - Boards come pre-veneered)

(Incidentally what would the smallest board thickness be that you would do a biscuit join on? 15mm, 18mm?)

Also what about a simple plywood shelf (~560mm wide), floating on 4 supports.
- (i.e. not screwed/ glued onto anything)
- is that more likely to warp over time?


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## TerryQ (Apr 8, 2014)

cabinetbuilding said:


> Terry, reassuring to know that you haven't had any issues with warping on your 12mm drawers. The veneer is just for the overall design style of the furniture piece. Thanks for the tip on the biscuit join. Box joins sound like a better idea. - (going for a clean look at the corners so prefer to avoid dovetail. - Boards come pre-veneered) (Incidentally what would the smallest board thickness be that you would do a biscuit join on? 15mm, 18mm?) Also what about a simple plywood shelf (~560mm wide), floating on 4 supports. - (i.e. not screwed/ glued onto anything) - is that more likely to warp over time?


If you already have a biscuit jointer just plunge cut into a piece of scrap wood and measure its depth. A quick look at a #0 biscuit (the smallest a basic jointer can cut) is 1-3/4 inches wide requiring at least a 7/8 inch deep (about 21-22mm) pocket. I have seen smaller biscuits in the stores, but have never used them. 

I would think a 12 mm plywood shelf that's only 560mm (22 inches) would stay flat with 3 braces, especially with a little weight on it. If you have the capabilities you could use a narrow board with a groove either routed or cut with table saw to reinforce the shelf and dress up the front edge of it. I did something similar to some shelves I made for some cabinets I recently built for my home workshop.


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