Greg Guarino wrote:
I may have asked about something similar a long while back, but I'm
getting closer to doing it now.

I need to build a one-piece "top" for some off the shelf bookshelf
units. The top will have two functions: to make the three units appear
more like one integrated piece of furniture, and to provide a durable
sun- and water- proof surface to cover the damaged tops of the units.

The three units together are about 9' long and about 30" tall. They
used to sit under a long south-facing window. We intend to move them
back there. In addition to the fading and other sun damage to the
tops, there were a few spills over the years; we had some potted
plants there.
I intend to use some sort of tiles as the "field" surface; big ones,
20" wide probably. They will sit in a "tray", made of 3/4" ply with a
1x2 solid wood border on all four sides. The top of the 1x2 will
either be flush with the top of the tile, or perhaps a hair lower. I
figure I'll use pocket screws to fasten the 1x2 to the ply.

So, here are my questions:

Should I use ply? Or would MDF work just as well? None of it will be
seen, and it will rest on the tops of the cabinets, so it won't hold
any weight.

What should I use to fasten the tiles to the ply? My original thought
was "nothing". Gravity and the "border" could hold them in. But I
wonder if gluing them down somehow would make them less prone to
cracking should something drop on them. Of course, if they're not
glued, they'd be easy to replace.

Your top is going to be well supported so you could use pretty much
anything. I'm not a fan of MDF so I'd use ply, especially if there will
ever be any water around.

The tiles are not going to bear any weight and being well adhereed isn't
going to stop them from breaking if you drop something on them; actually,
they aren't all that easy to break that way. Possible but not easy.

I assume you are going to grout them. Yes or no, I'd still stick them down.
For what you are doing, I'd probably run a bead of cheap acrylic caulk
around their perimeter an inch or so from the edge and an X across
them...put them down, put some pressure on them to squish down the caulk.

With that, you should be good to go as long as you don't try to lift the
top. If you plan on doing so, you need it beefy enough so it doesn't flex;
if it does, the tiles aren't going to break - unless it flexes a *lot* - but
the grout may crack. I think what you propose will be beefy enough.

--

dadiOH
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