How to Pour a Waterfall Edge
A waterfall edge can be trendy, elegant and practical. It adds visual impact and can turn a basic kitchen into something clean and modern. It can also be used to hide plumbing or electrical wiring, provide support for an overhang, or cover an unattractive cabinet or undercounter appliance. The downside is that it is not the easiest detail to achieve for a DIY project.
There are two ways to create a waterfall edge with a concrete countertop: pre casting or pouring in place. The guidance below is intended as general advice on how a waterfall edge can be achieved. The Concrete Set does not offer a one size fits all waterfall edge kit, but many customers have successfully formed and cast waterfall edges using our products. We will start with the easier option, pre casting.
Pre casting a waterfall edge for concrete countertops
This method is done in the same way as any other pre cast slab. You build a form, typically from melamine, to the correct dimensions, apply a release agent, and pour the concrete.
The width of the form should match the depth of the countertop it will sit beneath.
The length of the form should match the distance from the floor to the underside of the finished countertop.
The thickness will usually be between 38 mm and 57 mm.
There are a few things to consider when deciding the thickness. A standard square edge form produces an edge thickness of around 38 mm. You can make your waterfall panel the same thickness so it aligns cleanly. If you want the waterfall edge to match a thicker countertop edge at around 57 mm, you will need to allow extra overhang so the waterfall panel can be poured thicker. This is done by allowing the cement board to overhang the cabinet on the side where the waterfall edge will be installed.
When pouring, include reinforcement such as fibreglass mesh or welded wire mesh. Most pre cast concrete countertops will have small air pockets or pinholes once flipped, so slurry and polishing is normally required before installation. A slurry is a fine patching mix used to fill pinholes or voids along the surface and edges.
When pre casting, it is strongly recommended to wet cure or keep the slab covered with plastic for 48 to 72 hours. This reduces the risk of curling, which happens when the exposed surface cures faster than the concrete inside the form.
After curing, sand and seal the waterfall panel in the same way as the main countertop. Once installed, use a patching material to blend and disguise the seam where the countertop meets the waterfall edge.
Cast in place waterfall edge for concrete countertops
Pouring a waterfall edge in place is much more difficult than pre casting and is not recommended for beginners. The main advantage is that there is no seam between the countertop and the waterfall edge. The downside is that if the form fails or leaks, the results can be serious.
If you are confident enough to attempt this method, start by preparing the cement board in the same way as the rest of the countertop. The forms will need to be mitred so they continue down the vertical face of the cabinet.
Cut the cement board to size and install the forms, clips and reinforcement mesh. Once everything is set, install the cement board on the side of the cabinet. Pre cut a piece of melamine to size and place it over the side forms. This melamine must be securely fixed and all seams sealed.
You can secure the melamine using woodworking clamps or by building a custom brace. Temporary bracing should be fixed to the floor to prevent the melamine from bowing under the weight of the concrete. Adequate bracing is critical and it is better to over brace than under brace. If the melamine bows or concrete starts to leak, it will result in a significant mess and likely failure.
Fill the waterfall form slowly so the concrete settles properly. Vibrate the melamine during the pour to help air escape and reduce voids. After curing, remove the melamine, patch any air pockets or surface defects, and apply a concrete sealer.
Whichever method you choose, The Concrete Set recommends using a flowable concrete mix such as our Off White Mix or our Admix system. If you are unsure which products to use or how much material to order, contact us by email or complete our enquiry form and we will help ensure you have everything needed for your project.
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