horizontal slat doors- preventing contraction expansion problems?

[Jim Underwood]

I've been looking at making some horizontal slat doors (not louvered) for cabinets, and wondering how to prevent expansion and contraction problems. If you have a 40" tall cope and stick door, and glue up a solid horizontal grain panel, you're going to have some terrific expansion problems. I wouldn't be surprised if the panel didn't pop off the top and bottom rails at the first weather change... Even if you coped and ship lapped 2-1/2" wide by 1/2" thick slats and stacked them in the door frame, you'll still have expansion problems...

I'm wondering how to overcome that..

Any ideas on the best way to construct such a door?

[Mark Salomon]

You can't prevent expansion/contraction, if you try to you'll split the door. Why not deepen the groove in the rails enough to accommodate the likely expansion and hold the panel/slats in place in those grooves with spaceballs? If the slats are not glued to each other then they'll center themselves with they expand/contract. If they're glued up to form a single panel you can pin the center (you can do it from the back if you don't want the pin to show) to hold the panel in place at the center and it will expand/contract but remain centered in the frame.

[HANK METZ]

If you add a fixed center rail, the grooves help take up the wood movement plus it would be in keeping with the design character. Either center it or use the 60/40 split for a little more visual interest. Another design varient is running the slats at a 45 degree angle, as is commonly done on exterior European doors and shutters.

- Beachside Hank

[Lee Schierer]

If your panel is red oak and you have a 40% relative humidity change from season to season you would see about .66" change in width of your panel. This can easily be accommodated if you anchor the center of the panel and allow half the expansion at the top and the other half at the bottom with a 1/2" deep slot in your rails, then the expansion should not be a problem. Just be sure to completely finish your panel on both sides before assembly so that when it shrinks, you will not have exposed unfinished wood. The only problem I see would be determining your starting point for initial panel sizing. I would shoot for a 6% MC to insure the wood will never shrink unless you move to the high desert.

See the Shrinkulator (http://www.woodbin.com/calcs/shrinkulator.htm) to do your own calculations.

[Josiah Bartlett]

I have a few of those style doors that I have made around the house. Don't forget that the rails and stiles expand and contract too, so as long as they are similar species the differential expansion is what you worry about. Just don't glue the panel into the rails/stiles and make sure there is enough room for expansion. I haven't have a bit of a problem with mine.