How to create forms for concrete countertops

Updated February 21, 2017

When remodelling your kitchen, one change that you can make is to install a new countertop. While many people have traditionally used building materials such as tile, vinyl or stone, you can also use concrete for countertops. Concrete is a very durable substance, and by adding pigment to the mix, you can make the countertop almost any colour that you want. But before you pour the concrete, you need to build the form for it first.

Measure the dimensions of the existing countertop. Cut two 3-inch wide plywood strips that match the length of the countertop, and two 3-inch strips that match the width. Glue these strips together to create a frame that matches the edges of the countertop. This is the template you will use to create the form.

Lay the template down on a piece of melamine board and trace the outline. Remove the template, then cut the melamine with a jigsaw to create the bottom of the form. The melamine board is a plywood board with a plastic coating that will help prevent the concrete from sticking to the form.

Cut strips of melamine to fit around the sides of the bottom panel of the form.

Nail the strips of melamine to the sides of the bottom panel to form the retaining walls for the concrete.

Trace the template for the new sink on a one-and-a-half-inch thick piece of rigid foam insulation. Cut the sink template out of the foam with a jigsaw.

Punch holes in a different piece of foam with a one-and-a-half-inch diameter pipe and remove the foam pieces from the pipe. These pieces will be used to mark the faucets and spout in the form.

Cover the edges of the form with clear packing tape to prevent the concrete from sticking to the foam.

Attach the foam pieces that you cut out for the sink, faucets and spout to the bottom of the melamine form with silicone caulk.

Cover the inside corners of the form with silicone caulk to create rounded edges for the countertop.

Spray caulk-shaping spray over the silicone in the joints and smooth it out with your finger.

Things You'll Need

  • Tape measure
  • 3-inch-wide plywood strips
  • Glue
  • Melamine board
  • Jigsaw
  • Hammer
  • Nails
  • Sink template
  • Foam insulation, 1 1/2 inches thick
  • Pipe, 1 1/2-inch diameter
  • Clear packing tape
  • Silicone caulk
  • Caulk shaping spray
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About the Author

Carson Barrett began writing professionally in 2009. He has been published on various websites. Barrett is currently attending Bucks County Community College, pursuing a Bachelor of Arts in sports management.