Pour a Concrete Countertop for an Outdoor Bench

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. 

Cast your own Concrete Countertop for a Potting Bench with a Galvanized Corrugated Metal Roof
Cutting the base of the form with a jigsaw

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. 

Cast your own Concrete Countertop for a Potting Bench with a Galvanized Corrugated Metal Roof
Coating wood form walls with spray urethane

The walls are screwed to the base with self drilling cabinet screws.

Cast your own Concrete Countertop for a Potting Bench with a Galvanized Corrugated Metal Roof
Attaching walls to the form with 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

Cast your own Concrete Countertop for a Potting Bench with a Galvanized Corrugated Metal Roof
Tapered pipe cut from larger section

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.

Cast your own Concrete Countertop for a Potting Bench with a Galvanized Corrugated Metal Roof
Attach sink hole disc to bottom of form

The plastic pipe will he held in place with a few blocks of wood and a metal scrap.

Cast your own Concrete Countertop for a Potting Bench with a Galvanized Corrugated Metal Roof
Hold downs for pipe

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.

Cast your own Concrete Countertop for a Potting Bench with a Galvanized Corrugated Metal Roof
Caulking the concrete form with latex

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.

Cast your own Concrete Countertop for a Potting Bench with a Galvanized Corrugated Metal Roof
Caulking the concrete form with latex

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