The #1 Mistake Many Pool Builders Still Make
There’s one mistake we see all the time in new pool construction.
It’s simple.
It’s inexpensive.
It takes very little time to do correctly.
And when it’s skipped — it can ruin the look of your pool for years.
That mistake?
Not waterproofing behind the waterline tile.
What Is Efflorescence (And Why Should You Care)?
If you’ve ever seen a pool that’s only a year or two old with a white haze forming on the tile, you’ve likely seen efflorescence.
Efflorescence is a white mineral deposit that forms when:
- Moisture moves through the concrete shell
- Minerals and salts travel through the grout lines
- They deposit on the face of the tile
Tile itself isn’t permeable.
Grout is.
So moisture travels through the grout lines, bringing calcium and minerals with it — and that’s what creates that chalky white buildup.
And once it starts, it’s extremely difficult to stop.
The Simple Fix Most Builders Skip
Waterproofing the tile line behind the tile.
That’s it.
Before tile is installed, a waterproofing membrane (like RedGard or a similar product) should be rolled onto the bond beam — the top portion of the concrete shell where the waterline tile sits.
The correct process looks like this:
- Prepare and flatten the surface
- Apply waterproofing membrane
- Install thin set
- Set tile
- Grout
It’s not complicated.
It doesn’t take long.
It doesn’t cost much.
Yet many builders skip this step.
Why Skipping Waterproofing Is a Big Deal
When waterproofing isn’t applied:
- Efflorescence forms through grout lines
- White haze builds up on tile
- It’s extremely labor-intensive to remove
- It usually comes back
The most common removal method?
Scraping with a razor blade for hours.
And even then, it can return.
In some cases, efflorescence can even push against the back of the tile. If poor thin set was used or the tile wasn’t installed correctly, tiles can loosen or pop off.
It’s a small shortcut that can create long-term headaches.
Common Misconceptions
“It’s just salt.”
Not usually. Efflorescence comes from minerals in the concrete shell.
“Thin set makes it waterproof.”
No. Thin set is not waterproof. It is adhesive. A true waterproofing membrane must be applied first.
“Shouldn’t you just seal the grout?”
Not necessarily. Grout type (standard or epoxy) depends on the application. Sealing grout does not replace proper waterproofing behind the tile.
What You Should Ask Your Pool Builder
If you’re interviewing contractors, ask this direct question:
“Do you waterproof the tile line before installing tile?”
If they say:
- “Thin set handles that.”
- “It’s not necessary.”
That’s a red flag.
Waterproofing behind the tile is one of the easiest steps in the entire build — and one of the most important for protecting the long-term appearance of your pool.
Final Thoughts
A swimming pool is a major investment.
Something as small as skipping waterproofing can:
- Diminish the appearance
- Create constant maintenance issues
- Affect tile longevity
It’s a small detail — but small details are what separate a good build from a great one.
If you’re building a pool, make sure this step isn’t overlooked.