MICROCEMENT ON STAIRS

ASSESSING THE QUALITY OF THE SUBSTRATE

Correctly assessing the quality of the substrate is extremely important and determines the success of the entire project. The substrate for microcement should be load-bearing, without loose parts, the screed should not be very recent (wait a minimum of 28 days). Ideally, the stairs should be made of precast concrete. Then we have practically nothing to worry about, as they are almost perfectly straight and smooth. Worse if they have been sloppily poured or are covered with dried mortar that has fallen off when plastering, or if they are old and crumbling. In the following paragraphs we describe how to prepare the substrate for microcement. However, it is worth saying at the outset that when the substrate is of questionable quality or you are uncomfortable with bringing it out properly, it is better to say no to the client than to risk cracks or other surprises. Microcement is a very versatile product, but sometimes it is better to explain to the client that another material (e.g. a board) would be a better solution under the given conditions.

SURFACE PROTECTION AROUND

When carrying out finishing work, especially on stairs, protecting the remaining surface from accidental damage is crucial. One of the basic steps you should take is to protect the walls near the steps with strong painter’s tape. Be sure to choose a heavy-duty tape that adheres well to the surface and does not leave marks. This will protect the walls from possible dirt or mechanical damage.

The second step is to adequately protect the floor at the bottom of the stairs. For this purpose, the use of paper, thick painter’s foil or painter’s felt is recommended. Choosing the right protective materials can significantly reduce the risk of damage and make the renovation process easier.

STAIRCASE SANDING

Unfinished/developer condition stairs, which have no finish, require special attention and preparation before further microcement application work. Stairs in development condition may have various types of unevenness or even remains of concrete or other building materials. Grinding allows these imperfections to be removed, which is a key step in preparing the substrate for further work. What do you grind concrete with? The unfinished staircase should be grinded with an angle grinder with a concrete grinding wheel. This type of tool effectively and quickly removes irregularities and unnecessary layers of material from the surface of the staircase.

Next, once the grinding of the cement stairs is complete, it is important to vacuum the surface thoroughly. Then vacuum thoroughly to remove dust and any loose parts. We recommend using industrial hoovers, which are more effective at removing large amounts of dust and dirt.

PRIMING (FIRST TIME)

The next step in finishing the staircase is to level it. However, before this can be done, the stairs need to be primed to even out the absorbency of the substrate and improve the adhesion of subsequent layers. Levelling a stair involves bonding a cement board to the treads and then pouring a self-levelling screed over it. By priming the stairs before levelling, we improve the adhesion of this screed to the stair treads.

To prime the stair surface before levelling, use our acrylic substrate primer, FESTGRUNT, which will improve the absorbency of the substrate and improve the spread of the self-levelling mortar.

LEVELLING STEPS

Depending on the quality of the substrate, the steps must be levelled to achieve perfect angles and the same step height. How do you level concrete steps? For this purpose, the technique of reprofiling the steps with cement boards (e.g. Cementex) works well.

• First cut the boards to the right length and prime them.

• Then glue them (e.g. with tile adhesive) to the treads and, if necessary, make a formwork of gypsum boards and seal the joints with foam.

• Then pour a suitable amount of self-levelling screed on the treads.

• Once the screed has set, any irregularities should be sanded down and the next step can be taken.

PRIMING (SECOND TIME)

Before proceeding to the application of microcement, the levelled steps must be primed. For this step, we also recommend using our surface primer, FESTGRUNT, which seals the substrate, prevents water from being drawn off the mortar, increases the adhesion of the mortar to the substrate, improves the spreading of self-levelling mortars and is vapour-permeable. If microcement is laid without priming, it can become loose or poorly bonded and soft.

• The surface should be hardened, dry and clean.
• Apply the primer with a roller or brush.
• Allow to dry for 2 to 4 hours. After this time, further work can be carried out.

Worth reading:
What do you know about priming? Priming for microcement

MICROCEMENT APPLICATION

To create a microcement staircase, you can use a traditional microcement set for floors or ready-to-use microcement. Spread the mixture using trowels and other metal tools to a thickness of no more than 1 mm. Apply in quick, energetic movements in different directions depending on the desired effect, always using the wet-on-wet method. After about four hours, when the material has completely set and is dry, the stairs should be sanded using an eccentric or orbital sander with 60-80 grit sandpaper. After sanding the stairs, the entire surface should be thoroughly vacuumed. The second coat is then applied in the same way as the first.

You can find out what the entire microcement application process looks like:
– from the technical data sheets of our microcement systems,
– from our YouTube channel, where we present the whole process step by step.

SEALING

Finally, we cover the stairs with two layers of sealer. The stairs are exposed to abrasion, so the sealer must be very resistant. In this case, a two-component polyurethane sealer for microcement and concrete, PU FEST 2K, will work best. For exterior stairs, a dedicated exterior sealer, PU FEST TURBO, should be used. It is also important to use a good quality roller. Cheap rollers leave lint on the sealer which can ruin the end result. Before using the roller, we recommend wrapping it with masking tape to remove any loose lint. Sealing requires wearing a protective paint suit with a hood and shoe protectors. This way, no pollen from clothes, sand from shoes or hair will fall on the freshly painted stairs.

Worth reading:
Mistakes when sealing microcement – don’t do it!