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Home Building Articles

Caulking an Undermount Sink in Place

January 12, 2010

Builders' Tip: Caulking an Undermount Sink in Place

I needed to affix a stainless-steel undermount sink to a granite countertop that was already installed on its cabinet bases.

One problem I faced in tackling the job was how to get a good silicone-caulk seal between the underside of the counter and the rim of the sink.

Rather than rely on a bunch of braces and shims to wedge the sink in place, I used rope and a couple of wood blocks. Here's what I did:

As shown in the accompanying drawing, I placed a wood cross brace over each bowl of the sink.

Then I threaded a length of small-diameter rope around each brace and through the drain holes. On the underside of the sink, the rope runs through a wood block under each drain tailpiece.

After running a bead of silicone around the rim of the sink, I rotated each block, shortening the ropes and drawing the sink upward with even pressure exerted around the entire rim.

The resulting joint is so strong it almost makes the mechanical fasteners redundant.

Caulking a Sink

— Andrew Sheppard, Madison, Conn.

Tips & Techniques provided by Fine Homebuilding.
©2009 The Taunton Press