Main Bathroom Renovation [Forming a Concrete Counter with an Integrated Backsplash]

The story of our concrete counter for our main bathroom renovation is a little long. I thought I would break it up and share how we made the form to pour it first because this totally worked! We wanted an integrated backsplash because it was going up against an uneven log wall. We also thought it would look cool. And since we have never finished concrete, we decided to pour it upside down. We were probably overreaching our abilities, but we never let that stop us, haha. In the end it turned out great and we are extremely happy with it. So here is what we did and hopefully it will be of use to someone. 

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Here is the plan, top view and side view (upside down)

Now to break down the design:

First, we figured out how high we wanted the backsplash. We chose 4-3/4".  We wanted a 2-1/4" thick counter, so the 3" minus the 3/4" thickness of the melamine gets us there.  The 7" was figured by adding the thickness of the counter (2-1/4") and the height of the backsplash (4-3/4").  

Next we determined the depth and width we wanted for the counter. We needed a 22-1/2" deep counter. Minus the 2" thick backsplash brought us to the 20-1/2" piece. A 1/2" overhang was included. Our cabinet is 72" long and butts up to the wall on the left, so we added 1/2" for an overhang on the right, for a total of 72-1/2" wide. So the main piece of melamine that will be the bottom of the form, but when flipped over will be the top of the counter, ended up being 72-1/2" x 20-1/2". 
When built, this section ends up looking like this. Remember it is upside down and the cavity on the left becomes the backsplash when flipped over.

Still with me?

The rectangle in the center is the sink cut out. This measurement was determined by looking at the underside of the IKEA semi-recessed sink we used. This cutout may even just be circles for the pipes if you are using a vessel sink. 

We chose to use a sink that the faucet mounts on to simplify how many cutouts we had to make. All of the pipes come up through the large hole. 
To get started, you need:

3/4" thick melamine (we needed one 4'x8' sheet total)
1-3/4" drywall screws
2-1/2" drywall screws
Kreg jig and screws
Wax (we used a toilet ring)
Modeling clay and heat gun or Silicone caulk
Caulk spreader/applicator 
Table saw
Clear packing tape

We cut the entire 8' sheet on a table saw to the 72-1/2" we needed. Actually my husband did this part without me, so I use the term "we" very loosely. Then he drew out each of the pieces on the plan and cut them with the table saw.  I don't have photos of this part because I didn't know it was happening.

We started screwing the pieces together to make the profile shape. This is the 3" high piece going on.

We fastened it together with drywall screws about every 10".

Next we flipped it over to attach the front of the backsplash. We used pocket screws with a Kregjig because we needed to be able to unscrew the form to remove it when the concrete was dry. Had we screwed it normally from the other side, the screws would have been buried in concrete and would have made a divet in the concrete.

The view from the other end. We used clamps as needed to keep the pieces square.


We ended up with this one raw edge on the inside of the backsplash mold.  We sanded it well and covered it with clear packing tape to give it a smooth surface that would not soak up concrete.

Next we marked out where the screw holes would go on the two end pieces.  Basically, tracing the profile shape of the plan.

And they ended up looking like this.

Then we attached the end pieces to the form. Once both ends are attached, it gave us the base to continue adding the pieces for the backsplash part. This is looking at it right side up.

This is the completed form, upside down as in the plan view and side view.  Here you can see where we added the box for the cutout for the sink.

The measurements on the plan are the outside edge measurements for the box. We put it together with pocket screws and attached it to the form with 2-1/4" drywall screws, pre-drilled.

Any exposed raw edges of the melamine were covered with clear packing tape to provide a smooth waterproof barrier.

It seemed like the screw heads needed to be protected from the concrete so that any spillage would not prevent us from unscrewing the form after the concrete was dry. We used a cheap toilet wax ring that we had on hand as a source for wax to cover the screw heads.  It worked really well and released pretty easily.

The last step in preparing the form was to fill in the interior joints of the form.  We chose to use simple modeling clay.  We rolled it into tubes and pushed it into the joints, using a heat gun to warm it and make it more pliable. And then we used a caulk applicator to smooth it and give it a small rounded edge.  An alternative to this method would be using silicone caulk to fill the joints. We ended up using both methods on two different pours. The clay produced a more rounded edge on the counter. The caulk was faster and produced a smaller round over, meaning more square edges on the counter.

We added a piece of rebar and some metal fencing for stability. This photo also shows the depth of channel for the backsplash.  Remember, this is upside down.

And one last view of the form before we poured the concrete.

So there it is. The concrete counter form for our main bathroom renovation. 
Please note that this is our experience making the form. If you plan on using this as a guide to build one, please double check all of your measurements and proceed carefully. 

1 comment:

  1. This whole process is so impressive!!! I feel like I could tackle it with this tutorial. It looks great against the logs!!!!!