Vanity Countertop

[James Hart]

I'm making a bathroom vanity for my daughter's bathroom. The cabinet is alder and my wife and daughter want the counertop to be Alder as well, all stained the same color.

I'm concerned about the stability of a solid wood slab, especially in a bathroom.

Could I glue the slab to a sheet of 3/4" plywood to make it more stable? If I can, what would you use to finish it to keep it as waterproof as possible?

Thanks,

Jim

[scott vroom]

Jim, how old is your daughter? I recall the puddles of water my kids left on the vanity around the sink when they were young. Will the sink be a deck mount vessel or self rimming basin? I'd be concerned about mold build up where wood meets sink. As for the finish, I guess I'd lean toward a plastic (Varathane?), with multiple coats built up before setting the sink. I'm sure other posters more knowledgable with finishing will give you a better answer.

[Gerry Grzadzinski]

Glueing the slab to plywood would be worse, as you won't be allowing the wood to move.

I'd finish it like a wooden boat. At least 3 coats of epoxy like West System, followed by 3-5 coats of varnish or polyurethane.

[Clarence Miller]

for a vanity or sink I would recommend laminate that looks like alderhttp://samples.wilsonartcontract.com/p-311-fonthill-pear-10745-60.aspx

[James Hart]

She's 20. The sink is kind of modern, sitting up on top of the countertop. Should minimize the water sitting around the perimeter of the sink.

[Joe Chritz]

Slabs of wood less than 1/8th inch thick are laminated to plywood all the time. ;)

Check this chart http://www.finewoodworking.com/pages/w00060_sb2.asp. I believe it was originally from Jeff Jewitt who you have probably seen cruising these pages.

Joe

[Bill White]

I'm thinkin' that alder is gonna be pretty soft for any type countertop. Adult or not, you're gonna end up with a dented top. Cherry would stain up pretty darned close.
Bill

[Jamie Buxton]

You are right to be concerned about the stability of solid lumber on a vanity top. Solid lumber wants expand and contract with changes in atmospheric humidity. Plywood does not. Gluing a thick (3/4") layer of lumber to plywood is likely to lead to cupping of the composite panel, and gaps between the boards. Gaps between the boards will allow water to penetrate the panel, and bad things will result. As Joe observed, you can glue a thin layer of wood (that's called veneer) to thicker plywood. The thick plywood is much stronger than the the thin veneer, and prevents it from moving.

You know, of course, that using wood for a vanity top is begging for trouble.
Even with adult users, it is going to get wet. Eventually the water will get through the finish and stain the wood. If you must use wood, varnish it well, including the panel edges and the insides of the holes you bore for plumbing. Caulk well under the faucet and under the lavatory basin, again to try to keep water away from the wood.

[Stephen Cherry]

Maybe use west system 105 epoxy with the 207 hardener to coat the top, including all wood, top, bottom, ends, etc, using a sponge type brush. This will seal it up tight (two or three light coats, make sure to pop the bubbles before they harden).

Over this, varnish for UV protection. You could even use the catalyzed varnish for long, long life. Stain before the epoxy.

I did this on my mahogany boat seats a long time ago, and they are still OK. Remember, wooden boats have been getting wet for a long time.

To keep things flat, maybe some battens running cross grained screw onto the underneath of the top, through elongated slots to allow for expansion, kind of like table aprons without legs.