Expert: Jamie Yocono - 12/17/2009

Question
QUESTION: I'm building my grandson a bed with four drawers under the mattress.  Each drawer will be 7 1/2" X 30" X 30".  My initial intent was to use 1/4" plywood for the bottom of each drawer.  My question would be, because of the area of the drawers, will 1/4" plywood be sufficient and not cause warping in the center of the drawer, or should I move up to 3/8" plywood?

ANSWER: Hi Ed,

The answer to your question sort of depends on the drawer construction and what will be stored in the drawer. Of course, it's hard to know what will go in the drawers over time, so yes, I would probably move up to 3/8" plywood just to make sure all your bases are covered.

But the construction of the drawer is also something to be addressed. Some people attach drawer bottoms by simply nailing or screwing the bottom onto the bottom of the drawer box. I don't recommend that at all.

A better way to assemble this drawer would be to run a dado on the inside of each drawer piece, at least a half inch up from the bottom. Yes, I know that means you lose that extra half inch. But if the drawer bottom is enclosed in a dado on all four sides, then you accomplish two things. First, the plywood edges are hidden, which is a good thing. And second, you add a lot of rigidity and strength to that bottom.

For the record, I make that dado one inch up from the drawer bottom on drawers that are this big. If you don't mind losing a little storage space, you could move yours up a little more, but a half inch is the minimum space up from the bottom.

If you make the drawer this way, you might even be OK going back to using quarter inch plywood for the bottom. If you feel like it's going to sag in the middle, you could add a small center stretcher on the bottom of the drawer, in that half inch space, which will go a long way in cutting down on that sag.

If you have a brad nail gun, you could just nail that in place, and then run a small screws (and glue) down from the inside of the drawer into that stretcher, to keep them together. This stretcher isn't going to add a TON of strength, but it will stiffen that bottom up a bit.

OK, hope this helps. Write back if you have any other questions. And good luck with your project.

Jamie Yocono
Wood It Is! Custom Cabinetry
Las Vegas, NV
www.wooditis.com


---------- FOLLOW-UP ----------

QUESTION: Jamie
Although I did a follow up rating on your reponses, I do have another question that has appeared since our last communication.   I have since found drawer slides up to 36 inches.  So my drawers will now be 30 X 36 inches.  The two part question would be first, with the increased size would the 1/4" plywood still be OK with a support brace in the center of the drawer under the plywood.   The second question concerns the drawer sides.  I had thought of making them with 3/4" lumber, then I went to 1/2" plywood, but now I'm wondering because of the size of the drawers under the bed, that the 1/2" plywood, would not be a good choice for the long sides of the drawers?   What is you opinion?  Thanks
Ed

Answer
Hi Ed,

A drawer that is that big (30x36) probably needs beefier material for the sides than half inch stock. It's too likely to flex a bit, and your bottom could potentially slip out of the dado. I would definitely use 3/4" material for the drawer box, with that center support underneath. Make sure you glue the corner joints well, but not that bottom. It needs to float in that groove.

If you have a brad nailer or micro pinner, I would shoot the corners of the drawer boxes with those, too, to stiffen them up. That's a big drawer, no sense in taking any chances with it coming apart.

Hope you're using a heavy duty, full extension drawer slide, not a roller slide.  You are, right?

Good luck, hope this helps.

Jamie in Vegas

PS - if you send me your personal e-mail address, I will send you a hand-out that I give my students on drawer making. It's just a simple diagram, but it might help you out a bit. There's no way fro me to send it through this site, but I can e-mail it to you privately.