Hello,

I'm an amateur woodworker and small business owner (not related). I own a bar/coffee house and we are moving into a new bigger space.
In the new location, I've hired an experienced trim carpenter to build the bartop. It has a fairly deep overhang customer side (15"). Resultingly, for substrate, he has used a 1/4" steel plate topped with two layers of 3/4in plywood (seams overlapped). Plywood is screwed to the steel plate from below, and the two sheets of ply are glued and screwed together.

I've specified an edge glued up red oak slab countertop (He will be biscuting/dominoing them as well). He has built several bars and indicated he has always used troweled on glue to glue down the slab to the plywood and has never had a problem with separation or seasonal wood movement. However he normally builds it more like a floor and doens't edge glue he indicated.

Now, I'm an amateur, but I've read dozens of books and Fine Woodworking/etc. for the last decade of my woodworking hobby. Everything I think I know is that a glued up slab should NOT be screwed or glued to plywood. That with a table for example, we use some sort of attachment to the aprons that let the seasonal wood movement happen.

The big question: How should a glued up slab such as this (32" wide all said and done) be anchored to the plywood substrate? I'll take some pics when I'm at the jobsite later today. Being a $15,000 bar project, I want it to last for at least 10 years and not be pulling open at the seams or failing otherwise.

Any advice?