Hi @snowgoose62,
Raising the floor of your plunge pool by 100 mm can likely be done, but it’s not as straightforward as pouring new concrete over the existing surface. Because your current pool floor has already been coated with a waterproof membrane, new concrete won’t bond properly to it. The coating acts as a barrier, and if you pour concrete directly on top, the new layer is likely to separate, crack, or lift over time. For that reason, the coating would likely need to be completely removed before any new concrete is added, which involves mechanical grinding or other professional preparation methods.
Once the coating is removed, the new concrete layer would need to be bonded to the old slab using a bonding agent and potentially with steel reinforcing dowels. This helps the two layers act as one solid structure.
It’s likely best to consult a pool contractor or structural engineer for this kind of project. Raising the floor changes the structural load and could affect how the pool shell handles water pressure. A professional can confirm whether your existing base can safely support the added concrete and can recommend the correct materials and waterproofing system for your specific pool design. They’ll also ensure everything meets local standards for waterproofing and structural integrity.
While it may seem like a simple project, getting expert advice will save you from costly repairs later if things go wrong and help keep your pool watertight and safe.
Let me know if you have any further questions.
Jacob
