When we started our outdoor fire pit project we couldn’t wait to get to the point when we could try our hand at pouring our own concrete tops . After watching/obsessing over countless DIY videos/tutorials on how to set up the mold and pour the countertops we thought it would be smoooth sailing. Here is a pic of the fire pit before we created the mold.
First step was to head to the Depot and buy sheets of melamine. We then cut the melamine into 4″ strips so we could attach them to the side of the plywood base that would form our countertop. We wanted a 3″ thick concrete slab as our countertop.
You can see here we attached two strips of melamine using simpson A34 brackets at the corner. You could attach the two strips using only screws, but we had a bunch of simpson brackets laying around from an older project we decided to use. Plus they are cheap at $0.35 a bracket and create a nice 90 degree angle which made standing the vertical piece of melamime upright. We spaced the brackets at about 12″-16″ apart, we decided better safe then sorry. These vertical edges had to carry 3″ of wet concrete while the countertop cured, we didnt want to risk a blowout.
Once we set two vertical edges we decided to caulk the corner joint between the bottom and vertical piece of melamime. Most of the DIY tutuorials recommended this in order create a water tight mold and to end up with a smoothed out corner.
DAP caulking can be bought at any major hardware store, all you need is the caulk “gun” and a tube of it. It is pretty amazing the variety of choices you have when it comes to caulk. We happened to have a few tubes of exterior use water tight caulk laying around the garage. The only wierd thing is that it was brown. Usually we use white or clear caulk for interior work ( i.e. around base boards, doors and bathrooms). As you can see in the pick above, I had already squeezed out a line and smoothed it out.
Step 1: Try to squeeze out a continuous bead of caulk that is approximately the same thickness along the length.
Step 2: Once the bead of caulk has been squeezed out along the length, you have to smooth the caulk out with a tool, or in my case, my index finger
Step 3: make sure the smoothed out caulk is consistent along the length, with no air pockets. Since this is the underside of the countertop corner, I was not tooo worried about making it perfect.
Step 4: Use a wet paper towel/wash cloth if you really want to smooth out the caulk. (I skipped this step because of the afore mentioned reasons)
Once I finished caulking along the two long sides of the mold we finished assembling the short ends of the mold.
Here is the exceptionally overdesigned corner support. Leave it to two engineers to get crazy with a countertop mold!
Next I caulked the short ends and the inside corners to try and make this mold water tight!
In 30 minutes we had finished the mold and were ready to move on….pouring the countertop…eeeK