Is Microcement Waterproof? Sealer, Membranes and Wet Rooms

Short answer: microcement is water resistant once it is properly sealed, but it is not a waterproofing system on its own. In showers, wet rooms and around baths, it should go over a separate waterproofing layer. Get that wrong and water can find its way through hairline cracks or worn sealer into the wall or floor behind. Here is how it actually works.

Would you rather have it done for you? Our own applicators provide microcement installation across the UK.

Water resistant vs waterproof

The microcement coats are a mineral material, so on their own they can absorb a little water. The sealer is what stops water soaking in and makes the surface wipe clean. That is enough for splashes on walls, kitchen splashbacks and bathroom floors outside the shower. Where water sits or runs all the time, you need a waterproof membrane under the microcement as well.

Where you need waterproofing underneath

• Inside showers and wet rooms, on walls and floor.
• Around baths, especially the walls above.
• Shower trays and any area built to falls.
• Pool surrounds and outdoor areas.

Where sealer alone is usually fine

• Bathroom walls away from the shower.
• Bathroom and kitchen floors outside wet zones.
• Splashbacks behind sinks and hobs.
• Feature walls and furniture.

Why sealer needs looking after

Sealer wears with cleaning, foot traffic and time. Once it thins, the microcement can start to absorb water and stain. Using mild cleaners, avoiding abrasive pads and topping up the sealer when water stops beading on the surface keeps it protected.

The lime alternative

Some lime finishes resist water through a different chemistry, using soap or wax worked into the surface. They also need the right specification for wet areas. If you are weighing the options, read our Venetian plaster bathroom guide and microcement bathroom guide.

Questions

Can microcement be used in a shower?

Yes, over a waterproof membrane and finished with a sealer made for wet areas.

Does microcement need resealing?

Yes, from time to time. How often depends on use. Showers and floors need it more often than feature walls.

Can water get behind microcement?

Through cracks, worn sealer or badly sealed edges around fittings, yes. That is why the waterproofing layer underneath matters.

Is microcement good for a wet room?

It is a popular choice, as long as the floor is built to falls, fully tanked and properly sealed. See microcement shower trays.