"Water in Transit" Edge Details... Choices, choices...

Aquatic Technology Pool & Spa
Paolo Benedetti

Infinity edge pool, vanishing edge pool, knife edge pool, perimeter overflow pool, wet edge, zero edge, flooded deck pool, slot overflow pool, elevated perimeter overflow pool, disappearing edge pool... what ever you call them, they all have something in common - water flows over the top of at least one wall of the pool.

Imagine a bowl of water overflowing it's rim, or if the top is not exactly level - the water overflows in the lower area. This brings us to the various types of edge details available.

The "hottest" detail and most difficult to construct is a perimeter overflow detail called a "knife edge." The knife edge perimeter overflow pool has the water raised right up to the level of the coping. But instead of any water flowing over the coping, the water drops into a diagonal slot that meets the top inside edge of the coping. The water is right at the top edge of the coping, but then it falls into the slot that is under the coping. This is the most complex design, due to the difficulty in constructing the gutter & "knife edge." The edge must be dead-on level. Additionally, because the coping covers the entire gutter, there is no opportunity to go back & rework or waterproof the gutter, without breaking out coping stones.

The second most popular edge detail, goes by many names: "wet deck," "flooded deck," & "slot overflow." As it's name implies, the water flows over the top of a portion of the coping stones, before dropping into a gutter or slot. Amateurish designers & builders rely on garish plastic or metal grating atop an open gutter. This is a very industrial and archaic method of building this style of pool. These plastic grate gutter systems are still very popular in Europe & some developing countries, due to their ease of installation.

A more refined appearance for a perimeter overflow pool, can be achieved by overlapping the coping & decking stones over the gutter, leaving no more than a 1/2" gap - thus the "slot overflow" name. A gap wider than 1/2" is in violation of the ADA. It just asking for a toe/high heel to get stuck or torn off. This method also requires that the portion of stone that is to be underwater be durable, submersible, and installed absolutely level.

One of the most striking designs is one of my personal favorites, the elevated perimeter overflow pool. As the name implies, the walls of the pool are elevated above the grade & the water flows over the top of the wall. The raised portion can vary from a few inches in height to as high as 18". Any higher than 18" and the pool becomes difficult to enter. It also poses a safety issue for those standing on top of the wall, if it is any higher than 18".

Though I will never publish it, my personal pool is of this elevated overflow style. The face of the 18" elevated walls are clad with polished absolute black granite. The top surface (that spans the thickness of the wall), was treated to provide slip resistance. The surface of the granite was "flamed," resulting in a natural sanded type of texture. The interior is lined with a custom blend of black, gray, and deep purple mosaic glass tiles from Bisazza Mosaico, Vicenza, Italy.

The most familiar and common edge detail is the "vanishing edge," "infinity edge," or "disappearing edge" pool. These pools usually have one side of the pool lowered to meet the operating elevation of the water. The water spills over this wall(s) and into either a catch basin, or a gutter. Where a gutter is used, the water is transported to a remote holding tank, from where the edge effects pump draws it's water.

Adding to the complexity of all of these choices, is the myriad of combinations of the various effects. The most complex pool that my firm has ever designed & constructed (though not the most expensive), combined a staggered vanishing edge, knife edge, perimeter overflow, and collection gutters. Executed flawlessly, the final results are absolutely breathtaking. To review an in depth article about this project, visit the following link:

http://www.aquatictechnology.com/articles/t_cubed.htm


Paolo Benedetti - Aquatic Artist
"Creating water as art."™
Aquatic Technology Pool & Spa
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