"Larry Blanchard" wrote in message
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On Thu, 25 Oct 2012 18:30:48 -0400, Dick Snyder wrote:

Thanks. The widest board will be 7" x 74 1/2". I was most worred about
length but I do have room on width as long at I place the two end
pieces, which will be at a 90 degree angle to the long boards, with
screws in oversized holes so the long pieces can move.

Movement along the length is almost non-existent. Your end pieces are
"breadboard ends", lots of info out there on those. Depending on the
finish, 1/4" per 12" may or may not be enough.

Dewaxed shellac or oil based polyurethane do the best job at slowing
water vapor from moving in or out of the wood, but nothing will stop it.

Thanks Larry. I will just be using teak oil on this project so it matches
the entertainment center I made.

I think the breadboard ends idea will work well. Of course this isn't
exactly a breadboard with an end piece attached to the main breadboard. My
breadboard will be two pieces of teak sandwiched over a piece of bluestone.
The breadboard end will be just over 3" high and will have to be attached to
the top and bottom boards of the sandwich with a tongue and groove. It will
will allow me to hide the mechanical fasteners on the top and bottom of the
boards that will hide the existing mantle. I can cut plugs so even the screw
heads won't be seen easily. I suppose I could even make teak dowels but I
think screw heads hidden by plugs should work well on this project.