Prep for Saunas & Steam Rooms
MicroRock Base is used in Saunas & Steam Rooms, to ensure ground water won’t affect the microcement system. It is a very strong epoxy based products so has some special requirements:
Strength of Substrate
MicroRock can only be installed on a substrate with a minimum compressive strength of 25N/mm2 (aka MPa) and a Tensile strength of 1.5N/mm2 (aka MPa)
Surfaces must be completely flat before microcement is applied. It will follow the contours of the substrate and can’t be used to fill large voids. Blocks and bricks will need to be rendered with concrete before microcement is applied.
Generally, the following surfaces meet the necessary critera, but please check with the manufaturer to be sure:
Preparing Concrete, Screeds, Concrete Render
Cured to less then 10% moisture content
If there is still moisture in the substrate, the microcement could blister or de-laminate as moisture is trapped under the surface. Surfaces that aren’t fully cured are also more likely to crack as they do so whilst curing. The moisture content can be tested with a moisture meter or by checking with the manufacture of the screed. The drying time will depend on the depth & the type of product used.
Repair cracks under 3mm wide
Use a 5” grinder to open up the crack (take care not to cut into any underfloor heating), hoover out any dust then mix Epoxy with Epoxy Hardener (Ratio 5:2) and pour into the crack. Leave to cure fully this will take for at least 12 hours. It may need topping up depending on how deep the crack is.
Repair cracks over 3mm wide
Use a 5” grinder to open up the crack and grind approx 100mm “stitches” horizontally across the length of the crack around 40mm apart (take care not to cut into any underfloor heating), hoover out any dust then insert steel helical stitching bars into the stitches. Mix Epoxy with Epoxy Hardener (Ratio 5:2) and pour into the crack. Leave to cure fully this will take for at least 12 hours. It may need topping up depending on how deep the crack is.
Do not Prime the Surface
It is best to go directly onto the surface with MicroRock Base, no primer or mesh. However if there are a lot of cracks &/or joins in the substrate. It may be appropriate to use epoxy, mesh & sand blind.
Preparing Cement Boards
You can apply this kit onto cement boards but you must use the Epoxy Mesh & Sand Blind by choosing the High Performance Primer when you order your kit.
Epoxy, Mesh & Sand Blind
Reduce the chance of movement transferring through to the surface by applying Epoxy, Mesh & Sand Blind over the entire floor. The epoxy will also fill the joins and screw holes to level off the floor.
If both walls and floor are to microcemented, use wide adhesive skrim to bridge the internal corner before applying the Epoxy. Use a trowel to apply an even coat of Epoxy over the sub-floor and mesh. You’ll need to ensure you have completely filled the joins and screw holes in the sub-floor and also completely covered the mesh, so that it has good adhesion with the floor.
Whilst the Epoxy is still wet, spread the quartz sand across the surface. You can scatter it by hand, starting at the entrance to the room and walking on the sand into the room. Or by walking on the Epoxy with spiked shoes. The following day, sand any high spots and hoover up all the loose sand.