Pour a Concrete Countertop for an Outdoor Bench

In this episode of the garden potting bench build I’ll make the form and cast the concrete countertop, then add the sink and upper and lower shelves. In the previous episode I built the frame, poured footings to secure it to the ground, and added a corrugated metal roof. This is Part 2 of the series.

See the Youtube Video and download the Plans.


Background for Pouring the Concrete Countertop

Pour a Concrete Countertop for an Outdoor Bench
Watch this video on YouTube.

(transcript of the Build Video Part 1)

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

This video will focus on pouring the concrete countertop,  setting it on the top rails, installing the sink and drain plumbing, and adding the top shelves, then finally adding the bottom shelves with the corrugated panel back wall.

Cast your own Concrete Countertop for a Potting Bench with a Galvanized Corrugated Metal Roof
3D model of potting bench

Concrete Countertop Form

The cast concrete countertop will be poured in a shallow form made with a melamine coated board and one by walls.

Cast your own Concrete Countertop for a Potting Bench with a Galvanized Corrugated Metal Roof
Concrete countertop form

The back of the countertop will be notched around the center back 4x4 support. I’ll be casting two holes during the pour: one for the sink, and the other for a waste shoot.

Cast your own Concrete Countertop for a Potting Bench with a Galvanized Corrugated Metal Roof
Formed concrete countertop 3D model

Make the Countertop Sink Knockout

I need to create a hole in the countertop for my DIY sink I’m making from a stainless steel mixing bowl. I didn’t have any pipe or anything else the right size for this so, I’ll have to make a disc from scratch. 

Cast your own Concrete Countertop for a Potting Bench with a Galvanized Corrugated Metal Roof
Cutting a disc with jigsaw

I glued two squares of 3/4″ plywood together to give me a 1 – 1/2″ tall disc. Which is also the thickness of the counter I’m making. When the glue dried I scribed a circle with a compass. Then rough cut this disc with a jigsaw.

Sand the Blank Smooth

I slightly tilted the table of my disc sander to create a draft angle on the disc. Then I rotated it to sand it round and smooth.

Cast your own Concrete Countertop for a Potting Bench with a Galvanized Corrugated Metal Roof
Sanding the knockout on the disc sander

I gave it two quick coats of spray polyurethane to seal it from the concrete. To keep it from absorbing any water and hopefully make it easier to knock out after the concrete hardens. 

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

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