You’ve heard the expression before: “Measure twice cut once”.
When it comes to concrete slabs, this is doubly important because an error in judgment or a lack of uncovering underlying issues, is much more costly when coating concrete than with just about any other renovation or addition to a structure.
It’s very important to test for multiple conditions in concrete before finishing a floor. This is especially true when choosing a finish that is not porous and doesn’t allow the slab to breathe.
If there is contamination in the slab that has not completely gassed off (evaporated) or been worn away, this may not even be noticeable prior to putting a coating down. Once the floor can no longer breathe, you may become surprised to see some unwelcome additions to your finish such as; bubbling, hollow spots or complete de-lamination can be the end result of trapped floor contamination.
It is also very important to check the slab porosity, hardness, pH levels and moisture content.
There are do it yourself ways to test all of these variables; however, they typically only test one extreme end of the range of measurement.
Concrete flooring professionals can provide you with the results and peace of mind you need prior to making an investment in decorative or protective concrete flooring. In fact, even if you are installing your own tile or hardwood it is always a good idea to have a concrete professional come to your project and test for moisture and porosity prior to install.
In the case of hardwood flooring, high moisture can cause warping and swelling. With tile, low porosity could leave to a bad bond of the glue or mortar.
When working on concrete close to exterior walls or foundations or even in garages, it is very common to see a white powder – called efflorescence appearing due to high moisture content. While in some cases the moisture content causing this a efflorescence is low enough to be coated, however, in other cases if coating was the action taken, it would most certainly lead to a failure.
Hardness of concrete is also a factor when choosing to seal or paint. When sealing or painting a concrete slab it is very important to prepare the surface via abrasion. If the concrete is too hard, which can be measured using the MOHS scale, it very like won’t be a good surface to receive a topping until it has been grinded via diamond segments. This is because high hardness and low porosity are quite often found in the same places.
To ensure success with flooring over any concrete surface, your best bet is to have a concrete professional provide you some data on your slab before install.