This outdoor bar with a concrete countertop is a sturdy piece of outdoor furniture that serves as a nice place to sit and have a drink or as a food prep island. Concrete countertop slabs are pretty easy to make but are quite heavy so I recommend making this project near its final destination. This bar is made from 3 concrete slabs that bolted to support wall made out of 2x4s. This is one of the more challenging projects I have posted and it is critical to make sure that the bolts, which are cast, into the slabs are aligned with each other.
Cut the Melamine board.
I cut the 3 ½” wide strips of melamine board to use as the sides of the molds. If you do this with circular saw clamp a straight edge to the board to serve as a guide. A table saw makes this step a little easier.
Assemble the molds.
It is important that the 2 side slabs are the exact same size and that all 3 slabs are the same width so take care when assembling the molds. I used short pieces of 2x3 as supports and screwed the laminate boards to them.
Check your molds.
I checked to make sure the corners molds are at perfect right angles with a large speed square.
Glue the corners.
I like to make sure the corners of the molds will hold. I glue them tightly together using a hot glue gun.
Seal the mold.
I used silicone caulk to seal the edges and corners of the mold from the inside. I lay down a bead of caulk and then smooth it with my finger.
Sand the 2x6.
I used an orbital sander to sand the 2x6. I started with 100 grit paper to round down the edges and then finished with 220 grit.
Make the bolt holders.
You only get one shot at casting the bolts into the slab. It is important to make sure that the bolts in the 3 slabs will align with the support wall. I cut extra pieces of the melamine board into strips that are the same width as the molds. I then measured and drilled holes that the bolts can fit through. I didn’t want the supports to touch the wet concrete so I glued small pieces of ½” thick plywood to the ends of the so that they will hover ½” above the surface of the concrete.
Prepare the rebar.
I cut the ½” rebar with a reciprocating saw. I then wired the pieces of rebar into frames that will serve as reinforcement for the slabs. The frame should be about 3-5 inches from the perimeter of the molds.
Get the bolts ready.
Insert the bolts through the holes in the supports and use washers and bolts to keep them from sliding through. Adjust the nuts so that the bolts head will go about halfway into the slabs. I used 3 bolts in each of the slabs.
Mix and pour the concrete.
I mixed the Quikrete 5000 in a large plastic mixing tray using a hoe. I then shoveled it into the molds until they were 3/4s full. I placed the rebar frames onto the wet concrete and then filled the molds to the top. The rebar will settle deeper in the concrete as you work the surface above it. Use the hoe to push down the concrete as you fill the molds.
Screed and trowel.
I used a straight scrap board to screed the top of the concrete. Work the screed back and forth to level the concrete. I let the concrete set about 30 minutes and then used a metal float to work the cream to the surface. I spent about 2-3 minutes working the surface of each slab.
Cover + Keep Moist.
I covered the concrete with some boards and a sheet to make sure that nothing touched the wet concrete. I used a garden hose to keep the concrete moist over a 72-hour period.
Remove the molds.
After letting the concrete cure for 72 hours I removed the molds.
Build 2 frames for the support wall.
I used to 3” deck screws to connect 2x4s into 2 rectangular frames.
Drill holes for the bolts.
I aligned the rectangular frames and marked the locations of the bolts. I then drilled ¾” holes through the frame. I wanted the holes to be slightly larger than the bolts so that I could adjust the frames against the slabs before tightening the nuts and locking them place.
Assemble the support wall.
I cut 2 pieces of 2x4 to serve as base and top plates for the support wall. I tilted up the side slabs with the frames loosely bolted in place and then screwed the frames to the baseplate 2x4. The slabs are heavy so it is a good idea to have some help. Drill holes through the top plate and the top of the frames that align with the bolts in the top slab. Then screw the top plate onto the 2 frames.
Place the top slab.
Lift the top slab into place. The slab is very heavy so be careful about smashing fingers between the slabs. I recommend using at least 4 strong people to lift the slab into place and guide the bolts through the holes in the support wall.
Tighten the bolts.
Once the top slab is in place and properly adjusted and aligned you can tighten all the nuts to secure the slabs to the support wall. Since I drilled large diameter holes I needed to use large washers to fasten the slabs to the support walls.
Clad the support walls.
I cut, sanded, and stained the fence boards before screwing them onto the support wall. I clad both sides of the support wall since I intend this bar to be used from both sides. If the bar ever needs to be moved I can just take off a few of fence boards and release the bolts so that the slabs can be moved individually.