How to Complete the Form and Pour Concrete for a Vanity Top
DIY pros show how to complete building a form and pour concrete for a customized vanity top.
Concrete offers great versatility for shape, size, thickness and color. In our project, we designed a concrete vanity-top with exposed glass. Begin the project by surveying the site where you'll install the vanity.
Check to see if the wall is square and decide on what dimensions are best for your vanity project. In our project, we created a vanity 39 inches wide and 2 inches thick with a curved front.
Once you've purchased the vessel bowl and faucets for your vanity, carefully take note of measurements for the sink, hardware and the envisioned concrete top. In our project, the faucets would be hard to reach behind the glass vessel sink so we built two small backsplash shelves on either side of the gooseneck faucet for the handles also in the same 2-inch thickness.
It's a good idea to have your vanity base selected or purchased in advance. It's important to make sure the height of the vanity, once you add the concrete top and vessel sink, is comfortable for washing hands. In our project, we created a concrete pedestal but you can use a pre-made base, a cabinet with four legs or any other option.
Next, create a template out of thin wood veneer or masonite to the exact size of the proposed vanity (Image 1).
Cut the wood with a sharp table saw and make the curves with a jigsaw.
Do a dry run by positioning the template in the installation space as it's far easier to make changes to the template than to the finished vanity. Finalize the placement of the sink and hardware on the template (Image 2), outlining their location with a marker.
With the template design and hardware location finalized, build the watertight form for the concrete. The forms for the vanity and backsplash shelves are created by attaching 2" melamine rails to a melamine base. The front curved rail of the form is made of high-density foam.
Flip the template over onto the melamine (the top of the vanity is the bottom of the mold). Next take careful measurements of the sides of the template pieces and cut 2" melamine rails to fit. Make a curved rail by cutting a 2-inch square piece of foam and then routing out one square inch to create a shelf for securing the foam to the melamine.
Cut the melamine pieces using a sharp table saw. Melamine chips easily and chipped melamine isn't waterproof.
Tip: Before you start assembling the form, drill a screw through the bottom of your template. After you build the form around it, lift up on the screw to remove the template.
Secure the rails to the melamine base and around the template with clamps (Image 1).
Pre-drill holes with a piloting bit through the rails every six to eight inches then screw in 2-1/2" screws (Image 2). Pre-drilling holes helps prevent the melamine form from splitting when the screws are added.
Next, pilot drill and fasten the rails to each other with shorter screws. Take your time as the poured and dried concrete will hold the exact shape of the form. Repeat the process for the backsplash form rails. Remove the clamps.
To create the curved rail for the front of the vanity, waterproof the face of the form that will be exposed with clear packing tape. Packing tape will also give the concrete vanity front a shiny finish.
Secure the foam at the top of the curve with screws. Then secure the foam at each end and attach additional screws all the way around. Use small blocks of wood or melamine along the outside edge for additional support (Images 3 and 4).
Finally, remove the template from the form by carefully pulling up the screw added earlier.
In the next phase of the project, the form is completed and the concrete is poured.