Bathrooms · 6 min read
Is microcement waterproof in showers? The honest answer
Yes — when applied as a complete CimentArt system with the right primer, reinforcement and two-component polyurethane sealer. Here's what 'waterproof' actually means.
By Jonathan Heywood · 4 May 2025
This is the single most asked question we get. The short answer is yes — but with a caveat that matters: waterproofing is a property of the entire system, not of the microcement itself.
The system, not the surface
A shower-grade microcement build is a layered system: a tanking membrane on the substrate, two base coats reinforced with fibreglass mesh, two finish coats applied wet-on-wet, and finally two coats of a 2-component polyurethane sealer. Skip any of these and waterproofing is compromised.
Why microcement beats tiles for wet zones
Tiles leak through grout. Microcement has no grout. There are no joints to fail, no silicone to discolour, no membrane behind the wall waiting to be punctured by a fixing. The waterproofing is the surface you see — visible, sealed, and inspectable.
Where waterproofing goes wrong
- Wrong sealer. Single-component acrylic sealers are not rated for continuous wet exposure.
- Substrate movement. A flexing plywood floor without proper decoupling will telegraph cracks through any finish.
- Skipped mesh. The fibreglass reinforcement in the base coats prevents micro-cracking — it is not optional.
- Untrained applicators. The CimentArt training programme exists for a reason — wet-zone work is unforgiving.
What you can expect from a Cornwall Microcement shower
A fully waterproof, seamless shower in any CimentArt colour. A 10-year warranty on the system. A surface that looks better at year five than tiles do at year one. Book a free site visit and we'll walk through your substrate, drainage and finish options before quoting.