Tanning ledges: the shallow shelf everyone uses

What a tanning ledge actually is

A tanning ledge — sun shelf, Baja shelf, tanning shelf, the names all mean the same thing — is a large flat platform set 10 to 40 cm below the water surface, usually at 15 cm. It is not a step and not a bench. A step is something you pass through; a bench is something you sit on with water at your chest. A ledge is a room: wide enough to lie down on, shallow enough to hold a lounger and a glass, and wet enough to keep you cool while the sun does its work.

That combination is why it wins. Ask owners which square metres of their pool get used most and it is almost never the deep end. The ledge is where the toddler plays within arm's reach, where the adults sit out the hottest hour, where the towels and the coffee end up on a Saturday morning. It is the part of the pool you use when you are not swimming, which is most of the time.

It is also the one feature that is essentially impossible to add later. It belongs in the first sketch, not the last.

Depth is the whole decision

At 10 cm the ledge looks perfect in photographs and disappoints in use. The water is too thin to cool you, a lounger's frame stands proud of it, and one person getting in sends a wave that leaves you briefly stranded on wet concrete.

At 15 cm everything works. A lounger sits stable, the water covers your back and calves, and the surface ripples over the shelf instead of sloshing off it. That is why almost every ledge lands at 15 cm. If you plan to buy in-water loungers, check their base height first — most want 12 to 20 cm.

Deeper than 25 cm and you have built something else: a toddler pool, or a very generous bench. That is a legitimate choice if small children are the point, but nobody will lie down on it. Remember the freeboard too: in a skimmer pool the water already sits about 15 cm below the coping, so a ledge with 15 cm of water over it has its floor roughly 30 cm down from the deck — one comfortable step.

Size it for the furniture, not for the drawing

A sun lounger is about 2 m long and 70 cm wide. So a ledge meant to be lain on reaches at least 2 m into the pool, and 2.2 m is better — it stops your feet hanging over the drop. Under 1.8 m you have a wide step with ambitions.

Width decides how many people. 1.6–1.8 m takes two loungers pushed together; 2.5–3 m takes two comfortably with a gap for a side table. A ledge running the full width of one end is the most architectural answer and the simplest to build, because it just meets both side walls.

Then check the share. On an 8 × 4 m pool a full-width ledge reaching 2 m in takes 8 of 32 m² — a quarter — and still leaves a 6 m swim. On a 6 × 3 m pool the same idea takes a third of the water and there is no pool left. Small pools should add the ledge to the footprint rather than carve it out of the water.

A tanning ledge is the only part of a pool that gets used more when nobody is swimming.

Where it goes: sun, terrace, wind

Three things decide the position. Sun, because a ledge in shade is just a wet floor — put it at the end that keeps the afternoon light, and check what the house, the fence and any mature tree shade at four in the afternoon in July, not at noon in May. Closeness to the terrace, because everything that ends up on the ledge is carried there: towels, drinks, a book, a child. And wind, because the ledge's thin water is where floating debris lands first.

In practice the ledge almost always belongs at the shallow end, beside or opposite the steps, so the whole shallow zone is one continuous place instead of two islands separated by a swim. That keeps the deep end clear as well, which is exactly what the swimmer wants.

What it does to the rest of the pool

Two consequences, both easy to miss on a plan. First, a ledge is not swimming area. Size the swimming part of the pool as if the ledge were not there — this is the most common sizing mistake in the whole hobby, and it turns a good 8 m pool into a mediocre 6 m one.

Second, a ledge removes water. Eight square metres at 15 cm holds about 1.2 m³; the same footprint at 1.4 m would hold 11 m³. So a generous ledge takes roughly ten cubic metres out of the volume you heat and treat. With a heat pump that is a real, permanent saving, and it is one of the few pool decisions that makes the pool nicer and cheaper to run at the same time.

How it gets built depends on the shell. In a concrete pool a ledge is a formed slab: cheap, any shape you like. In a liner pool it needs a shaped former under the membrane and generous radii. In a one-piece fibreglass shell the ledge is whatever the mould has — you choose a model, not a size.

Thin water goes green first

A ledge collects every disadvantage water can have: shallow, still, warm and in full sun. Chlorine burns off faster there, the surface can run several degrees above the rest of the pool by late afternoon, and if the shelf sits outside the circulation loop nothing ever flushes it.

The fix is cheap and has to happen during the build: at least one return inlet feeding the ledge, either in the wall below it aimed along the shelf, or a floor inlet in the shelf itself. Without one, your algae season starts here every year, weeks before the rest of the pool.

The finish matters too. The ledge is the most-scrubbed and most-looked-at surface in the pool, under 15 cm of very clear water. Pale plaster shows every leaf, and a textured, non-slip finish is worth more here than anywhere else, because this is the surface people stand on wet.

Details to buy while the shell is open

An umbrella sleeve cast into the ledge floor turns a two-hour zone into an all-day one. During the build it costs almost nothing; afterwards it means drilling a finished pool. Ask for a sleeve with a flush, removable cap so there is nothing to stub a toe on.

A bubbler — one low geyser jet in the middle of the shelf — is the water feature children actually use, and it stirs the thin water while it does it. And the drop-off deserves a marked edge: a band of contrasting tile along the line where 15 cm becomes 1.4 m, so that nobody walks off it in the dark.

Test the size before you commit

Put masking tape on the terrace at the exact dimensions and set your real loungers inside it. Lie down. This takes ten minutes and settles the 1.8 m versus 2.2 m argument better than any drawing.

Then open the 8 × 4 family plan in the designer, switch the tanning ledge on and set its width, its reach into the pool and its depth; the swim area left over changes as you drag. Between a roll of tape and a free plan you will know your ledge dimensions to the nearest 10 cm before you ask a builder for a price.

What goes wrong in practice

1. A ledge too shallow to lie on

   At 10 cm the water stops cooling you and every wave exposes the lounger frame. Fifteen centimetres is the depth that works; it is also the depth people regret skipping.

2. A ledge stolen from the swim area

   On a 6 × 3 m pool a full-width ledge 2 m deep takes a third of the water and the pool stops being swimmable. Add the ledge to the footprint instead of subtracting it from the water.

3. No inlet under the ledge

   Thin, warm, sunlit water with no flow is where algae starts. One return inlet aimed along the shelf, planned during the build, saves a chemical fight every summer.

4. An invisible drop-off

   A shelf that ends in 1.4 m of water with nothing to mark the edge is the one genuine hazard a ledge adds. A contrasting tile band costs almost nothing and reads clearly even at dusk.

5. Forgetting the umbrella anchor

   By mid-afternoon the ledge is the hottest place in the garden. Retrofitting an anchor means drilling the finished shell, where a cast-in sleeve is a few minutes of a builder's time.