A guide to planning custom GFRC concrete countertops, covering thickness, overhangs, integrated sink design, and faucet clearance. First in our concrete countertop design series.
Concrete Countertops 101: Design Considerations
Concrete countertops are one of the most customizable countertop materials available. Custom concrete countertops can be cast into virtually any shape, color, or finish while minimizing visible seams and accommodating unique features such as integrated sinks, drainboards, waterfall edges, and custom edge profiles.
Like any custom product, thoughtful design during the planning stage helps ensure the finished countertop is both beautiful and functional. The following guidelines will help you make informed decisions before fabrication begins.
Countertop Thickness
Our countertops are manufactured using Glass Fiber Reinforced Concrete (GFRC), allowing for thinner profiles and longer spans than conventional reinforced concrete while maintaining excellent strength and durability.
The recommendations below serve as general design guidelines. Large sink openings, cooktops, grills, unsupported corners, or other significant cutouts can substantially reduce structural capacity and may require additional reinforcement, increased thickness, or strategically placed seams.
These values are intended as general guidance only. Final thicknesses and reinforcement requirements are determined during shop drawing review.
Countertop Overhangs
We recommend a minimum countertop overhang of ¼ inch, with ½ to 1 inch preferred for most installations.
This slight overhang helps conceal minor irregularities in cabinetry, millwork, stone veneer, brick, or other wall finishes that may not be perfectly straight or plumb. A properly sized overhang also creates a cleaner shadow line and produces a more finished appearance.
Integrated Sink Design
Our integrated sinks are fabricated using precision-built molds that produce smooth, consistent surfaces requiring minimal finishing. Every sink is designed with proper drainage slopes and can accommodate a variety of plumbing configurations, including:
- Standard residential drains
- Commercial drain assemblies
- Bottle traps
- Slot drain systems
The two most common sink styles are:
- Ramp-style basins
- Box-style basins
- Front Ledge Requirements
To maintain structural integrity and allow space for concealed support, we recommend maintaining a minimum 3-inch ledge between the front edge of the countertop and the sink basin.
Longer countertops or countertops with large sink openings may require wider ledges depending on span, reinforcement, and loading conditions.
Faucet Planning
One of the most common installation issues has nothing to do with the sink itself. It's the faucet.
When maximizing sink size, it's easy to overlook the clearance required beneath the countertop to install the faucet mounting hardware.
Most deck-mounted faucets require a 1⅜-inch diameter mounting hole. To properly tighten the retaining nut from below, installers generally need at least 1 inch of clear access between the edge of the sink basin and the backsplash or wall.
Planning this clearance during design prevents difficult installations and may eliminate the need for specialty mounting hardware.
When possible, we recommend selecting the faucet before finalizing sink dimensions so both components are designed to work together.
This is the first post in our concrete countertop design series. Future posts will cover additional topics like finish types, seam placement, and more, so check back as we continue building out this resource for anyone planning a custom concrete countertop project.
