Safely Attaching Cooktops to Solid Surface Countertops

by Michael Chotiner

With most kinds of countertops, installing a cooktop is a slam dunk—literally. Once the electric or gas supply is in place and you've got a cutout of the right size and shape, you generally just need to drop the unit in and follow the manufacturer's directions for making the appropriate hookup (see How to Install an Induction Cooktop, for example).

Invariably, those directions instruct you on how to fasten the cooktop in place by clamping it to the counter from below with whatever proprietary hardware is supplied. But solid surfacing is more heat sensitive and prone to cracking than other countertop materials. The counter itself (and especially the cutout) need the right kind of support and special treatment to reduce the risk. Experienced professional installers know that clamping or screwing a cooktop to solid surfacing is asking for trouble.

Cutout Size and Shape

If a kitchen is properly designed—that is, there will be adequate clearances around the spot where the cooktop is to be installed—the first order of business is to make sure that the cutout is the right size and shape. Unless you're highly skilled and have a powerful plunge router with a carbide straight-cutting bit, it's best to leave the cutting to a fabricator. The fabricator will most likely fashion the cutout using a manufacturer-supplied template, which may or may not account for the extra clearance needed around the cooktop to allow for expansion and contraction and reduce the risk of cracking a solid-surface counter.

Tell your fabricator to:

  • Base the size of the cutout on the actual measurements of the cooktop body—that is, the housing that sits below the countertop. S/he needs to add 1/4 in. to the actual side-to-side and front-to-back of the housing to ensure that there will be a 1/8 in. space all around the housing when the cooktop is centered in the cutout.
  • Cut radiuses at all the corners rather than leaving them square, which would increase the risk of cracks. Base the curve of the radii on the width of the cooktop flanges; the wider the curve the better. It's okay to have the flanges covering the cutout by as little as 1/8 in. at the corners.
  • Glue 6 in. by 6 in. reinforcing blocks of solid surfacing at all corners. Use seaming adhesive and spread it generously over the surface of the block that will mate with the underside of the counter. Once it has cured, use a router to trim the block flush with the radii at the cutout corners. Then, again with the router, bevel the edges of the reinforcing blocks at 45 degrees where they meet the cutout edges.
  • Sand all cutout and reinforcing block edges smooth, working with successively finer abrasive grits up to 220.

Are the Counter and Cutout Adequately Supported?

Solid-surface counters should not be installed over a solid plywood or particleboard sub top. Instead, the counter should rest on an open framework of wood or plywood strips a couple of inches wide. With respect to the cooktop cutout, support strips should be in place not further than 3 in. from the cutout edges, but not closer than 1 in. Make sure adequate supports are in place at the front, back and sides of the cutout.

Let's Go to the Tape

Before dropping the range into the cutout, apply aluminum reflective tape to the cutout edges to deflect heat generated by the cooktop when it's in use. Aluminum tape is available in a variety of widths; 2.5 in. will do fine for a cooktop installation since it's best to apply the tape to the inside edges of the cutout, then fold it over and stick it onto the countertop surface. Don't worry that the tape might extend past the cooktop flanges. It can easily be trimmed once the cooktop has been set in place.

With any countertop material other than solid surfacing, the next steps would be to set the cooktop in the cutout and clamp it to the underside of the countertop with whatever system was provided. Some instruction sets will tell you to take it easy on tightening clamps and/or screws on stone and solid-surface tops. Many experienced appliance installers know the risks of driving screws or exerting clamping force on solid surfacing and skip fastening the cooktop in at all, but unfastened, a cooktop is awkward, if not somewhat dangerous to use.

There are two good ways to avoid clamps and still get a cooktop battened down:

  •  Apply double-sided foam tape around the edges of the cooktop cutout, drop the unit in and center it, then burnish to cooktop flanges down onto the tape with a 2x4 or heavy roller to compress the tape and assure the bond. Trim away any excess aluminum tape that may extend past the cooktop flanges gently with a utility knife.
  • Instead of using foam tape, dispense marble-sized dollops of 100% silicone adhesive about 6 in. apart around the cutout. Center the sink in the opening and set the sink flanges in the adhesive, burnishing with the end of a 2x4 scrap. Trim clean any squeeze-out around the flanges immediately and trim away exposed aluminum tape with the tip of a utility knife. Let the adhesive cure for 24 hours before using the range.

By avoiding clamps altogether, you eliminate the risk of cracking the solid-surface top. And with foam tape or silicone adhesive, you can make sure that the top stays put.

About the author:  Michael Chotiner is an DIY author, craftsman, and former contractor that loves to share his pro knowledge about remodeling kitchens for The Home Depot. If you haven't already picked out your kitchen countertops, take a look here to see a variety of options.

Copyright 2019 G George Ventures Inc.