Preparing Surfaces

The surface that you are microcementing onto needs to be completely flat before the microcement is applied. So you can’t apply micorcement directly onto a breeze block wall. You will need to prepare the surface first.

Because microcement is very thin, with a finished depth of just 3-4mm, it can only be applied to a flat surface.

You can either overboard the breeze black wall or apply a cement render over it to get it smooth for microcement.

This guide explains more about preparing breeze block walls for microcement:

relentlessmicrocement.com/training/preparing-bricks-or-blockwork-for-microcement

Since there is a risk of moisture getting to the underside of the microcement, you can't go directly onto the surfaces with microcement. Instead, you will need to use a suitable tanking product to tank the surfaces before applying microcement.

Microcement is incredibly versatile, it can be applied to almost any substrate. But because it is trowelled very thinly, at just 3-4mm finished, it is very dependent on the surface that it is applied to for it’s strength & appearance.

This guide outlines the “golden rules” for preparing surfaces for microcement that must be followed in every case:

Essential Prep for all Surfaces: relentlessmicrocement.com/training/essential-prep-for-all-surfaces

The prep work required does vary depending on the substrate that it is being applied to & the state of the existing surface.

Some surfaces are easier to apply microcement to than others.

Our Surface Prep Guides detail all the common surfaces that you might be thinking of applying microcement to & explain in detail how you can prepare them so that they meet the necessary criteria.

relentlessmicrocement.com/microcement-training-and-installation-guides/surface-prep

As long as there is no risk of movement, tanking is not required because the microcement will act like a tanking sytem.

If the tanking system is already in place or you want to use one for extra piece of mind. You’ll need to make sure the tape is firmly fixed to the wall – especially along internal corners.

You’ll also need to flush it out so that you have a flat surface to microcement onto, as the microcement will follow the contours of the surface that it’s going onto.

This guide explains more about tanking & the prep required for it:

relentlessmicrocement.com/training/is-tanking-required

If you are still at the planning stage, then this is the ideal set up for microcement wet room:

Use a hard shower tray that is suitable for microcement and vinyl floors. Firmly fix the shower tray in place to eliminate the chance of movement.

Board shower area walls right down to the shower tray. Ensure boards are firmly fixed in place.

Silicone the joint between the boards & the shower tray/floors. Do not smooth out the silicone, leave to dry overnight and razor scrape off the excess. No silicone should be left on the surface.

There should be no gaps in any of the surfaces that are to be microcemented.

Ideally walls will be Aqua4ma panels or plaster boarded and skimmed. But you can go onto other surfaces with microcement, just let us know what you are planning and we can send you the relevant guidance on prep.

You can apply microcement on MDF, but it's better to use marine ply or cement boards in wet areas, because, if water gets to the MDF, it can doesn't cope well with it.

The only way to avoid water damage to the MDF is to fully coat all sides of each piece with microcement so that no water can get passed it to the MDF.

This is the ideal system for wet rooms, the panels are completely waterproof and rigid. And the solvent weld bonds the tongue and groove edges of the panels together very well. The solvent weld can also be used to flush joins between panels & cures within 30 minutes allowing you to sand it flat.

Here's the information for preparing Aqua4ma panels for microcement: relentlessmicrocement.com/training/preparing-kudos-aqua4ma-panels-for-microcement

And here are the install guides for the Aqua4ma panels:

relentlessmicrocement.com/training/installing-kudos-aqua4ma-shower-decks

The process is exactly the same for all boarded floors: OSB, Plywood, Cement Board. Once the boards are well glued & screwed in place, you will need to apply epoxy, mesh & sand blind aka High performance Primer, scroll down for detailed instructions on that process too.

Here's the information for preparing boarded floors for microcement:

relentlessmicrocement.com/training/preparing-boarded-floors-for-microcement

It’s important that all boarded surfaces, including cement board floors are completely flat & free from movement before the microcement is applied.

Because there are joins in the floor, we recommend applying high performance primer over the boards, this adds strength to the surface & helps to prevent movement transferring through to the surface.

Here's the information for preparing boarded floors, including cement board floors for microcement:

relentlessmicrocement.com/training/preparing-boarded-floors-for-microcement

Concrete, screeds and self-levellers are ideal surfaces to apply microcement to. Generally, they are flat and continuous, which is perfect for microcement.

It is important that the surfaces meet the following criteria before you start. These are covered in more detail here: relentlessmicrocement.com/training/preparing-concrete-screeds-self-leveller-for-microcement

• Cured to less than 5% moisture content
• Special prep for anhydrite screeds
• Put underfloor heating through a full cycle
• Repair cracks before starting microcement
• Never microcement over Cold Joints/Expansion Joints

Microcement is very versatile & can be applied to a wide range of materials to make furniture.

Timber composites like MDF, Plywood & OSB (chipboard) are good for building furniture out of before applying microcement. But you can also apply microcement to older furniture to give it a new lease of live.

Surfaces must be well consolidated, completely flat & free from movement.

Here's the information for preparing furniture for microcement in more details:

relentlessmicrocement.com/training/preparing-furniture-for-microcement

To get nice tidy corners with the microcement, it’s essential that the prep work is done right, surfaces need to be completely flat & free from movement.

This guide demonstrates how to prepare internal and external corners, with this is mind:

relentlessmicrocement.com/training/preparing-internal-and-external-corners-for-microcement

Our microcement range includes a number of products that can be used outdoors. This guide tells you everything you need to know about choosing the right surfaces & doing the prep right:

relentlessmicrocement.com/training/choosing-preparing-outdoor-surfaces-for-microcement

There are some limitations when it comes to ground level patios.

Read the guide below for full details of when to use it and how to prepare surfaces accordingly:

relentlessmicrocement.com/training/preparing-outdoor-patios-for-microcement

If you’re installing microcement onto a plastered or painted wall, then a lot of the work will have been done for you already.

The wall should be completely smooth and free from any movement before you apply microcement.

Visit our guide on preparing Painted and Plastered Walls for Microcement for more information on the process: relentlessmicrocement.com/training/preparing-painted-and-plastered-walls-for-microcement

Whilst microcement is very strong, smooth & flexible, it relies entirely on the surface (aka substrate) that it’s going onto to make it completely smooth and free from movement.

The surface must be flushed out and the chance of movement eliminated before microcement is applied.

This guide explains more about preparing steam rooms for microcement: relentlessmicrocement.com/training/preparing-steam-rooms-for-microcement

Tile-On Boards, like Wedi Boards, Marmox & Jacko Boards aren’t compatible with microcement on floors. They don’t have adequate compressive strength to hold the microcement rigidly.

Microcement can be applied to wall boards, but since they are fixed in place with large washers, that require a lot of flushing out, they require a lot more prep than some of the alternatives.

This video explains more about the limitations & explores some alternatives: relentlessmicrocement.com/training/choosing-the-best-surfaces-for-microcement-wet-rooms-bathrooms

If you already have Tile-On Boards installed, then this is the guidance on preparing them for microcement: relentlessmicrocement.com/training/prep-for-tile-on-boards

Tile-On Shower Trays aren't compatible with Microcement, because they aren’t strong enough to take the product. Often the waste is set too high for microcement as well, preventing water from flowing down the drain.

This video explains more about why they aren’t suitable & explores some alternatives: relentlessmicrocement.com/training/choosing-the-best-shower-trays-for-microcement

If you have a Tile-On Tray that has already been installed, then this is the guidance on preparing it for microcement: relentlessmicrocement.com/training/prep-for-tile-on-boards

It’s important that the surface is completely flat & free from movement before the microcement is applied.

To achieve this with floor tiles, you can either use joint filler to flush out the grout lines: relentlessmicrocement.com/product/cemher-joint-filler

Or for added strength, apply high performance primer over the surface.

This guide goes into loads of detail about each of the processes for preparing Tiled Floors for microcement:

relentlessmicrocement.com/training/preparing-floor-tiles-for-microcement

Because the microcement can only be applied on a completely flat surface. The grout lines will need to be filled in advance. Joint Filler is a great product for flushing out grout lines, it dries quickly & sands easily. relentlessmicrocement.com/product/cemher-joint-filler

This guide demonstrates the full process of preparing Tiled Walls for microcement:

relentlessmicrocement.com/training/preparing-wall-tiles-for-microcement

Once the screed or self-leveller is cured to with 5% moisture content, it’s important that the underfloor heating is commissioned & put through a full cycle before the microcement is applied. This will help to force out any movement cracks, which can then be repaired in advance of the microcement application.

Here's our full guide on using microcement on top of Underfloor Heating:

relentlessmicrocement.com/training/using-microcement-with-underfloor-heating

To avoid any problems with moisture getting to the underside of the microcement, we generally recommend building worktops out of marine ply or cement board, especially if the worktop is to be installed around a sink.

Once installed, the joins between the boards & screw holes will need flushing out, with a suitable filler & sanding back to get a smooth surface.

Here's some more detailed information on preparing Worktops for microcement:

relentlessmicrocement.com/training/choosing-preparing-worktops-for-microcement

You can install electric underfloor heating under or over the Aqua4ma panels.

If you install them over the underfloor heating, you will need to lay the heating wires, then screed over, then install the panels with flexible tile adhesive applied with a notch trowel.

If you install the heating on top of the panels, then you will need sufficient depth of screed, as recommended by the underfloor heating & screed manufacturers to give a solid, stable base for the microcement to be applied at a depth of 3-4mm.

We don’t recommend using angle beads with microcement. The microcement itself is a strong product, so doesn’t tend to need support in the corners. It’s also very thin, so angle beads would need flushing out before the microcement is applied.

You may decide to use a stop bead to bridge the join between the microcement and another surface.

For expansion joins, be sure to use an expansion joint allow movement along the join right through to the surface of the microcement.

It’s usually more straightforward not to use angle beads or stop beads, but if they are already installed here is our guide to preparing them for microcement, as well as a demonstration of the alternative approaches:

relentlessmicrocement.com/training/using-angle-beads-stop-beads-and-expansion-beads-with-microcement

The guide also explains the best approach to control / expansion joints, which do need to be followed through to the surface of the microcement.

We don't recommend using decoupling matts with microcement, because microcement is a very thin coating which needs to be applied to a solid surface. Since decoupling matts allow for movement on the surface, they're not compatible.

Instead, it's best to build a solid base. Either by applying high performance primer directly to floor grade tongue & groove boards. Or, in the case of underfloor heating, applying screed or self leveller directly over the under floor heating, then applying microcement onto that.

There is more detail on surface prep for those build-ups here:

relentlessmicrocement.com/training/preparing-boarded-floors-for-microcement

relentlessmicrocement.com/training/preparing-concrete-screeds-self-leveller-for-microcement

relentlessmicrocement.com/training/using-microcement-with-underfloor-heating

Microcement is very versatile & can be applied to most surfaces, but some require more prep work than others.

Generally, you’re aiming for a completely flat surface that is free from movement. For this reason, screeds on floors & plastered walls are ideal.

You can apply it to a wide range of other surfaces too. You might just need to do a little extra work to get it ready for the microcement.

Visit our surface prep guides for more information on the specific prep required for each surface:

relentlessmicrocement.com/microcement-training-and-installation-guides/surface-prep

Microcement can’t be applied directly to beam & block flooring. Before the microcement is installed, the surface needs to be completely flat and free from movement.

Your builder / flooring contractor can advise the best way of meeting these requirements. But generally, the beam & block flooring will be overlaid with a cement screed before microcement can be applied.

For more information on preparing beam & block flooring for microcement, see: relentlessmicrocement.com/training/preparing-beam-block-flooring-for-microcement

Because microcement, is applied very thinly, it can’t be applied directly to bricks or blockwork. Before the microcement is installed, the surface needs to be made completely flat.

You can either board over the surface or apply a cement render over it, to get a flat surface before applying the microcement.

This guide explains more about achieving a nice flat surface, ready for microcement:

relentlessmicrocement.com/training/preparing-bricks-or-blockwork-for-microcement

Outdoor surfaces need to be waterproofed (so that no moisture can build up on the underside of the microcement, or above ground level.

The external edges of the microcement must also be siliconed so not water can get behind it.

The following guide give more detail on preparing outdoor surfaces for microcement:

relentlessmicrocement.com/training/choosing-preparing-outdoor-surfaces-for-microcement

Limitations on Ground Level Patios

We don’t generally recommend using our microcement on ground level patios, since they are constantly exposed to ground water both below and around the external edges, which is very hard to control even when a damp proof membrane is installed.

For more information on preparing outdoor patios for microcement, see our guide: relentlessmicrocement.com/training/preparing-outdoor-patios-for-microcement

Microcement can only be applied to a rigid surface, so it’s important to choose the right shower tray & do the prep right.

This guide will help you to choose the best shower tray for microcement: relentlessmicrocement.com/training/choosing-the-best-shower-trays-for-microcement

And this guide explains how to prepare rigid & Aqua4ma shower trays for microcement: relentlessmicrocement.com/training/preparing-rigid-shower-trays-for-microcement

The easiest way to build a microcement sink, is to use a pre-formed undermount sink.

Cut the countertop to size & fit the undermount sink or basin firmly in place, so that movement is eliminated.

Next flush out the join between the sink & countertop with a suitable filler. You can use Joint Filler for this:

relentlessmicrocement.com/product/cemher-joint-filler

Make sure both the countertop, sink & the join between them meet the following guidelines:

relentlessmicrocement.com/training/essential-prep-for-all-surfaces

Then you can go ahead & start the microcement process.

Once complete, silicone the join between the sink & the waste, using the same technique that you would for shower wastes:

relentlessmicrocement.com/training/applying-silicone-to-the-join-between-microcement-shower-wastes