In article 36,
Patriarch wrote:

BTW, the solution is to stop the water. MDF will do the same as the
particle board. But even if the substrate were impervious to the water,
the damage will be done, if not there, then elsewhere. Mold, mildew and
dry rot are nasty, expensive things. And they encourage insects.

Well said. One thing that I do, and it seems to work well, is to treat
all the exposed edges after the sink hole is cut and the tap holes are
drilled, with silicon. I rub it into the end grain of the substrate and
a few inches wide all around the bottom where I put it on nice and thick
so it forms a ridge, in effect creating a drip-edge. I use the cheapest
silicone I can find...but it needs to be real silicone..none of that
paintable stuff.

When I build a custom laminate top, I always put a backer (balance)
sheet all around the sink area. In commercial applications, I cut a
piece of 1-1/4" PVC drain pipe the length of which is the same as the
thickness of the counter top. I silicone that in place creating a sleeve.
When building a custom laminate top, I install the sleeve first with
epoxy, then belt-sand flush with the top before applying the laminate.
Then drill and clean up with a bottom bearing flush bit.

Some of the things I do are over-kill, but I'm sure glad I don't get any
call-backs.

The fine folks at CounterSeal have this whole game down. Give them a
look. They have ways of undermounting sinks ....under laminate.
http://www.counter-seal.com/sche.html



Plywood is NOT a good substrate for laminate. If there is going to be
any lifting, the layer of laminate will just pull up the first layer of
veneer. (I'm assuming the glue-up was done properly)