Installing Polished Concrete Floor On An Existing Slab

Installing polished concrete floors on an existing concrete slab can create a beautiful floor finish but here’s what you need to know. A popular fitting in some of the most stylish homes and businesses, polished concrete floors offer a versatile decorative finish. What makes concrete floors an even more compelling alternative to other flooring options is its low maintenance and exceptionally durable attributes. Difficult to dent or scratch, DIY concrete flooring is not only cost-effective as a first-time installation but also promises low-cost long-term maintenance.

An affordable decorative floor solution, Sephaku Cement highlights key factors to take into account when fitting polished concrete floors on top of a pre-existing slab.

Ace the Base

The key to fitting long-lasting concrete floors is determined by the quality of the base or subgrade on which it’s installed. While easy to assume that placing concrete on an existing slab would be the most ideal condition to fit polished concrete floors, this can be a common misconception. The quality of the existing slab will determine the lasting durability of the polished concrete floors installed on the surface. If the integrity of the base slab has been compromised in any form this will adversely affect the concrete floor fitting on the surface side. (E.g. If the base-slab is cracked the top slab will crack in exactly the same places). As with any concrete floor installation, the base or subgrade on which concrete floor surfaces are installed must be adequately prepared and primed to provide a stable and sound foundation for your concrete polished floor. 

Partition the Two Slabs

When installing polished concrete floors on an existing concrete slab best practice recommends the two layers are partitioned, separating the slabs from making direct contact. Using a layer of river sand or plastic sheeting should do the trick but depending on the quality of the sub-slab, fitting steel rebar may be a better option which would also be effective in reducing the risk of cracking due to freeze-thaw shrinkage.

Check Your Measurements

Be sure to check floor height measurements and how placing polished concrete floors on top of an existing slab will increase the height. Installed anywhere between three (3) and five (5) mm in depth, keep in mind that even the slightest lip on any floor surface can create enough of a ridge to trip over. Another consideration to keep in mind is door hangings that that will also need to be measured to fit when original floors are raised.

Keep up with Routine Maintenance

While polished concrete offers some of the most durable and low maintenance flooring solutions available, placing polished floors on top of a pre-existing concrete slab may be more vulnerable to cracks and other damage. Servicing your polished concrete floors on an annual basis and inspecting for cracks in order to repair these as soon as they become apparent, will ensure lasting durability and a beautiful, polished floor surface. Routine maintenance of polished concrete floors includes cleaning of the surface with fresh water and a pH neutral soap and in-between wet water cleaning use a dry microfiber mop head to sweep away dirt and debris.