How To Make A Concrete Countertop

Over the summer our plastic and glass patio tables unfortunately had to be kicked to the curb for the garbage man. The wife wanted to replace it with an 8′ table. Something big enough to seat the entire family around it. After an extensive search through ugly and outrageously expensive possible replacements, we decided to make our own out of concrete. Here’s the CAM00075-1finished product. The dimensions of the table are 32 x 96 x 2 inches thick. We added a charcoal dye to the concrete mix to give it the greyish appearance  you see in the picture. The legs are an extruded aluminum that I rescued from the scrap bin at work. To make the form I used 3/4 inch birch plywood. After cutting it to size, I put a radius on the ends using a router  and a CAM00050 (4)trammel. Since the width of the table was 32 inches, I measured 16 inches from each end and 16 inches from the side to find center This is the location of my trammels pivot point. With the trammel pinned to the 16 inch mark, the router bit is set to the outside edges of the plywood. Once set I turn on the router and push it into the plywood counter clockwise, although with wood on both sides of the cutter it does not matter. Once I reach the other side I am careful to stop at the straight part of the table so I do not cut into it. In the picture you can see that I did not cut all the way through the plywood. I usually make 3  or 4 passes to complete the cut. The cut will finish smoother and the router will not have to work hard, resulting in less wear and tear.CAM00051

Here is the finished cut. This process is then repeated for the other end.

I wanted to be sure I got a nice smooth finish for the top of our table. To garauntee this I used plastic laminate. If you want a smooth finish, make sure your forms are smooth.

I used a water based latex contact cement to glue the laminate to the plywood. I find this type of glue to be easy to work with. It can be applied using a paint pan and roller. After a coat has been applied to both the plywood and the laminate, it must be allowed to dry completely to insure a good bond.CAM00056

 

In the picture to the right the glue is almost dry. You can see the roller marks in the upper right hand corner. These are wet spots. When the glue drys clear, it’s ready to stick. Drying time depends a lot on humidity.  It can take 10 minutes or 2 hours. A fan can be used to accelerate the drying time.

Once the glue dries, the two surfaces can be bonded. I use 3/8″ dowel rods to keep the two pieces apart so I can position the laminate  to cover the plywood completely. Once the laminate is where I want it, I pull the dowel rods out and stick the two surfaces together.CAM00062

The laminated surface is the will be the top of the table. This will insure a smooth surface.

Now the sides and ends of form need to be applied.  The curved ends were made using a bending plywood. The bending ply was ripped to 2 3/4″ wide and cut to the length of the radius. Contact adhesive was then applied to the two ends and  2 pieces of laminate. Once the contact dried I used double face tape to stick the finish side of the laminate to the curved edge of the form. I then stuck the bending ply to the laminate. I then pulled the piece away from the plywood edge which retained the shape of the radius.

CAM00066 (2)I then screwed the ends on with drywall screws. The screws were placed about 3″ apart so it fit tightly around the radius. I then fit 2 straight pieces of 3/4 plywood (2 3/4″ wide) on the sides of the table between the curved ends.  The ends of these pieces were also rabbeted  to wrap around the ends of the bending ply toconcrete table help secure them in place.

Next, a hole had to be formed for the the umbrella. This was achieved by  predrilling a 1 1/4″ dowel rod 2″ long and screwing it in the center of the table form. I placed a piece of 2″ PVC around the dowel and shimmed it in place for easy removal after the concrete set up. The PVC will stay in the concrete and be part of the finished product.

concrete table formAfter the form was finished, I applied a thin bead of caulk around the inside perimeter. This was done to seal the form and to give the finished product a soft edge when the form is removed.

The form is now ready for concrete. I estimated the weight of  the table to be about 400 to 500 pounds. For that reason I moved the form as close as possible to where the tables final resting place would be. I put the form on the edge of our deck on horses. I CAM00071put plastic down on the composite  decking to keep it protected from concrete stains and scuff marks.

After I poured a layer of concrete into the form, I placed rebar and wire mesh into it. I then filled the rest of the form with concrete and smoothed it out even with the top of the form. This would be the bottom of the table. As I poured the concrete into the form, I hit the bottom of the table with a hammer and had my help use a orbital sander to vibrate and settle the concrete into place to keep from getting voids.

Once the concrete set up, the form was flipped over onto another set of horses and the form was removed. This was done with the help of 3 other people. The slab was then slid over onto the aluminum frame and legs.

Because I used laminate for the inside of the form, it came out super smooth. If I was to do it again, I would use a countertop cement. I used a product called Cement-All and it set up faster than I liked, so I didn’t have a lot of working time.

 

 

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