Build the Concrete Countertop Mold
The bottom of the countertop form is made from 5/8″ thick Melanie coated board. I wanted to buy the 3/4″ thick board but in my haste I pulled the 5/8″ from the stack by mistake. It will do but the 3/4″ is stiffer so its preferred.
Anyways, I cut this to the final width and length of my countertop. I’ll mark the cut-out for the rear middle leg of the bench and cut this with the jigsaw.
Concrete Form Walls
The walls of the form can be made from strips of melamine but I had some one by spruce around so I ripped them to width, cut them to length, then gave them a quick two coats of spray polyurethane.
The walls are screwed to the base with self drilling cabinet screws.
I marked a line on the walls so the screws would end up in the middle of the melamine.
Round Waste Hole Formed from Pipe
The waste hole will be formed from a section of plastic drain pipe I found. I cut a section near the end of this pipe with a handsaw. This sectional had a nice taper to it as it reduced in diameter. I thought that would be just perfect for the waste shoot.
Attach Blanks to Base of Concrete Form
The plywood disc that will form the sink hole is screwed to the base of the form from underneath.
The plastic pipe will he held in place with a few blocks of wood and a metal scrap.
Seal all inside edges of Concrete Form
A bead of latex based caulk is added to all corners of the form and around the pipe and plywood disc.
I smooth this bead and remove the excess with my finger. I’ve been using latex caulk for most of my form work as I find it easy to remove later and it’s not so overly strong. And it’s usually a bit cheaper than pure silicone.
