Will A Microcement Crack?

A Crack In An Anhydrite Screed

Cracks in finished floor surfaces are common in all material types: tiles, resin, polished concrete, timber, vinyl. They just present themselves in different ways that are not always so apparent. Cracks in grout joints, ripples under vinyl, lippage in timber flooring etc. One floor surface is not inherently better than another at dealing with cracks.



Cracks come from the substrate below the finished floor and often caused by the modern floor designs we now aspire to have; underfloor heating systems, none rectangular rooms, columns in rooms, refusal to have movement joints, using insulation as a perimeter joint. Incorrect curing and drying of floor substrates and commissioning of underfloor heating are a major cause of problems.



Our microcement floor and wall products are designed to be dimensionally stable, shrinkage comensated with a high degree of flexibility. CARRcrete microcement products will not crack, unless they are forced to crack by tensile forces being applied to them in excess of the products design. This is the same for all microcement and microconcrete products on the market.



When we are asked to consult on cracked overlay floors (from a wide range of manufacturers) there is always one thing in common. The substrate (screed, concrete slab, tiles) has a crack beneath the micro overlay. That shows us that the crack has transmitted through to the surface from the substrate below. By slipping a feeler gauge into the crack, you will often find the crack penetrating far in excess of the thickness of the micro overlay.



If you imagine our product is just 3mm thick, or the thickness of 4-5 playing cards. It cannot be expected to hold back the movement in substrates such as floors and walls which are much thicker and have considerably more mass.



The key to crack free installations is to have well constructed and cured floor slabs and screeds that have been allowed to dry thoroughly, are installed over slip membranes and have movement and perimeter joints where required. During a site survey any cracks or problem areas where visible would be highlighted to the contractor/client.

