We love the industrial look the concrete desktop brings to our home office. The wood of this desk keeps things natural and brings a bit of warmth. Since the desk is pretty simple, we added shelves in the legs for a bit of extra storage.
How to Make the Concrete Desktop
- Melamine board (for concrete mold frame)
- Circular saw
- Measuring tape
- Drill and screws
- Painter’s tape
- Silicone caulk
- Hardware cloth (Wire mesh)
- Olive oil
- Concrete mix
- Concrete mixing tub
- Hoe (for mixing the cement)
- Orbital sander
- 2″ x 4″
- Mason trowel
- Plastic sheeting
- Concrete sealer
Creating the Concrete Mold
Cut melamine board to create side pieces and bottom of the concrete form. The side pieces should be the thickness of the melamine board plus the thickness you want your desktop to be (our side pieces were 2¼-in. because we wanted a 1½-in. thick counter).
Cut side pieces to length so that they form a square around the bottom, two of the sides will be the same length as the side of the bottom where they attach, the other two sides will be 1½-in. longer so that they overlap the other two sides.
Drill holes ⅜-in. up from the bottom edge of the side pieces to attach them to bottom of form. Also drill holes in the ends of the sides that are longer than the bottom.
Line side piece along the edge of the bottom piece and pre-drill holes thru so the wood doesn’t split.
Put in screws and screw together. Repeat with all four edge pieces.
Wipe the inside of the form to remove any sawdust.
Place painters tape around inside edge leaving a gap big enough for a bead of caulk. (Concrete can react with silicone, changing the color of it. The tape keeps any smeared caulk off the inside of the form, leaving just the thin line along the edge.)
Caulk along the inside edges, going up along the corner seams, too.
Smooth out the caulk with your finger to remove any excess and round the corner. Let the caulk dry according to directions on tube.
Once the caulk is dry, remove tape, make sure to pull tape back toward itself not sideways.
Set the mold on a flat surface and make sure it is level. Coat the inside (bottom and sides) of the mold liberally with olive oil. This is to keep concrete from sticking to the mold.
Mixing the Concrete
Pour concrete mix into mixing tub.
Add water a little at a time and mix until the concrete is about the consistency of oatmeal. You don’t want it too watery, as that can make a weaker counter.
Pour concrete into mold — it should be about half full– and smooth it out.
Once the cement is smooth, use an orbital sander along the outside edge of the form to vibrate the mold – this gets air bubbles out.
Cut the wire mesh so that there will be a ¾-in. gap between it and the inside of the mold. Then place the mesh in the center of the mold on top of the wet cement.
Mix more concrete, and pour it over the mesh. The concrete should now be level with the top of the mold. Smooth out and repeat the step above with the orbital sander.
Using a piece of 2 × 4, firmly press the board across the top of the form to smooth and level the concrete. Warning: This can get a bit messy.
Let the cement dry for a couple hours, then go over it with a trowel to help smooth it out.
Cover the mold with plastic, and let the cement dry according to the directions on the bag. We let ours dry for three days.
Once the cement is dry, remove the screws from the mold and pull off the sides. They will stick a little from the silicone.
Carefully lift the concrete top to its side, and pull away the bottom.
Sand off any rough edges.
We let ours dry for another day outside of the form.
How to Build Desk Legs for the Concrete Desktop
- Large piece of paper (or scrap wood) – for scale drawing of legs
- Measuring tape
- Pine boards
- Table saw
- Power planer
- Jig saw
- Hammer and nails or nail gun
- Wood glue
- Wood stain and/or polyurethane (optional)
Do a scale drawing of the legs (we did ours on scrap wood) to figure out the dimensions and angles. Ours are: 28½-in. tall by 9-in. at the bottom. We made our leg pieces 1½-in. wide.
Cut enough 1½-in. strips from the pine board to make the leg pieces in the drawing. Cut them 1/16 of an inch larger than you need so that when you power plane the saw marks off the edges, you will end up with 1½-in.
Cut your eight leg uprights to length, cutting the top and bottom of each piece at a 5-degree angle so that they sit flat on the floor and against the bottom of the table.
Cut your four shelf supports and your four upper desktop supports to length (ours were 23-in.). Cut a 5-degree angle along one long edge of each of these support pieces with the table saw so that the shelf and table supports sit flat.
Next, mark out the notches in the legs for the shelf and table supports to sit in, then cut out with a jig saw (you could also use a scroll saw or a coping saw).
Glue and nail the supports into the leg uprights making sure everything is kept square.
Using the table saw, cut a piece that will go between the two upper supports with a 5-degree angle on each of the long sides. (We determined the dimension of this from our scale drawing).
Glue and nail the piece between the upper support pieces. Cut shelf to size, cutting a 5-degree angle with the table saw on each side so that the edges will be flush with the leg uprights.
Smooth the edges with the power planer, and glue and nail the shelf in place.
Once the glue has dried, sand the shelf and legs.
Determine how far apart your two leg pieces will sit. This will depend on the size of your desktop and where you want the legs to be under the desktop. For ours, the outside of the leg pieces line up with the edges of the desktop.
Cut and attach two cross pieces to fit between the tops of the legs to secure the two sets of legs together and to give support to the desktop (we used 1×6 pine board and the two pieces were 33½”x 7¼”). If desired, a finish can be applied to the legs.
Attaching the Concrete Desktop to the Legs
Apply silicone caulk to the support boards where the concrete top will sit.
Set the concrete desktop on top of the silicone.
Apply sealer to concrete, following directions on the sealer can.
This project is part of our Cement DIY Challenge series here on The Home Depot Blog. We challenge some of our favorite DIY and decor bloggers to come up with a DIY project, and the only stipulation is that it involves cement.
Manda McGrath writes about DIY projects, cooking and family at The Merrythought. She lives in western New York with her husband and three boys.