Custom Laminate Counter - Spec?

[Russ Filtz]

Any of you pros out there have tips on how to spec a commercial/industrial countertop? This is going into an air conditioned space in central florida. I'm going to spec Wilsonart laminate (the heavy duty abrasion resistant kind) and their glues also.

What should the substrate be? I'm thinking 2 layers of 3/4 exterior grade ply, or would a ply/MDF combo be better? How many plys (do I need to go to BB for longevity)? I am a little worried about the MDF as if any seams aren't good, or you get chipped laminate, you can get swelling from all the humidity/rain (parts of the counter may get wet at there's a horizontal sliding window right next to it.

Do I NEED to laminate the bottom, or just specify some poly? I was going to spec spar urethane on all cut, unfinished edges as well. Any other tips? Thanks!

[Roger Everett]

Russ:
Generally all the comm/ind. mica cabinets and counter tops I've ever been involved with are spec'ed out to be plywood substrate. Counter tops get a balance sheet on bottom. Mica dealer used to sell balance sheet material, which was a mica sheet, but without any design on it ( just a plain dull brown ). Anymore most places now just generally use a discontinued pattern or some sheets of leftover material ( since it's not being seen). The balance sheet is to seal against any moisture from below, and to balance top against any warping that might have a tendancey to happen because of only one side covered. Same idea as when veneering , to veneer both sides.
Roger