Rhomba Concrete Bench


For our Rhomba Bench we decided to use cedar 2 x 4’s that were available at our local lumber yard and relatively affordable. While any species of lumber will work, there are some species that standup to the elements better than others.

Step 1 – Build the Bench Top

  • The bench top is constructed of 2x4s.
  • Follow the cut list in the instructional drawings for full details.
  • The length of the bench top can be changed depending on where it will be installed.

Step 2 – Install

  • The wood bench top drops down onto the concrete ends.
  • The bench can be easily relocated because it remains as 3 separate interlocking components.

Alternate Casting Methods

This how-to guide features casting the Rhomba Bench Cubes with a fiber reinforced concrete mix like CHENG D-FRC or Surecrete’s Xtreme Series products but you can also cast the cubes using CHENG Pro-Formula Outdoor Concrete Mix and Sakrete 5000 Plus Concrete Mix as shown in the following video.

The three main differences between these two approaches to pre-casting are the form construction, final project weight, and final cost. The form for fiber reinforced casting is easier to build, doesn’t require a center knock-out, and the final weight of the fiber reinforced concrete casting will be roughly a third of the Pro-Formula and Sakrete 5000 version. However, the cost of concrete material in the Pro-Formula and Sakrete version will be approximately one quarter of the fiber reinforced concrete method.

In this video Fu-Tung Cheng explains the marriage of form, function, and materials resulting in the successful design of this popular bench.

Previous: DemoldingRhomba Concrete and Wood Bench - Demolding and Polishing | CHENG Concrete Exchange

Carefully dismantle the form by removing all the drywall screws before extracting the concrete casting and take precautions to assure the….