Moisture’s role in preventing floor failures

by Darren
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Moisture and humidity are two key factors to consider when looking at floor failures, along with several other notable elements.

Nobody in the flooring industry deliberately sets out to install a floor in order to have it fail. This is especially the case in the commercial sector, as these floors have to withstand significant wear and tear on a daily basis. When speaking to industry experts in the flooring sector, or even conducting exhaustive research, the critical role that moisture plays soon becomes very apparent not only in preventing floor failures, but in ensuring that any installation is a success.

When looking to determine if a concrete slab is dry enough to proceed with a finish, flooring or occupancy, there are several methods commonly specified for testing the relative humidity (or moisture content) of the slab. A dry slab is never at 0% humidity, but determining the level of moisture still held in the concrete can determine either the success of a flooring installation or a problem-prone floor system.

Following the cracks

In the 1940s, moisture levels were tested by placing an enclosed amount of desiccant onto the slab surface for a period of time, with calcium chloride (CaCl) being the most common desiccant used for this type of moisture testing – often referred to as the anhydrous calcium chloride test. Any change in the weight of the desiccant was thought to indicate the amount of water vapour that had left the slab and been absorbed by the desiccant. That weight was presented as a ratio of the total moisture content within the slab, and was referred to as Moisture Vapour Emission Rate (MVER).

The real problem with MVER or CaCl testing lies in the fact that it primarily tests only the surface conditions of the slab. In any drying concrete slab, the moisture conditions within that slab are subject to a gradient effect, with higher moisture levels at times that are deeper in the slab. As moisture evaporates from the surface, additional moisture rises through the natural capillaries of the concrete in a progressive cycle until the moisture content in the slab reaches a balance with the ambient conditions. MVER is incapable of providing accurate readings of those internal moisture levels.

Smooth Solutions

In turn, relative humidity (RH) testing for concrete measures internal moisture levels of a concrete slab by placing sensors, or in situ probes, within the concrete slab itself. Testing that started in Sweden and elsewhere in the 1990s demonstrated that slabs which dried from one side required placing the probes at 40% of the slab depth, giving a reading that would reflect accurate moisture conditions for the slab if it were sealed, i.e. a floorcovering installed, at that point in time. Slabs drying from two sides require the probes at 20% of the slab’s depth.

Based on the realities of moisture vapour’s distribution in drying concrete, RH testing can accurately determine internal moisture levels, or relative humidity of the concrete. These differences between MVER and RH testing have had a profound impact on the flooring industry, allowing concrete and flooring installers to make informed decisions when choosing products that will tolerate actual RH levels of the slab, or allowing them to make remedial choices before elevated moisture levels result in flooring problems.

The SA Scene

Test equipment -SANS code of practice – 10070 for Vinyls –  Horse hair hygrometer 10043 for wood flooring – Electronic devices Recommended by manufacturers/suppliers: European manufacturers recommend the CM Gerratt

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We recommend that potential buyers explore the available options thoroughly before buying.

Protecting Installations

Often, flooring materials and installations are damaged as a result of being installed on a project too soon and not being properly protected until all following trades have completed their work. Scheduling work and product completion are crucial on the contractor’s and end user’s list of requirements to get a project completed, occupied and up and running to ensure businesses are able to proceed with their activities. Flooring installed too soon will turn out as a base for following trades to work on, and the material will inevitably be damaged.

Beyond moisture and humidity checking to prevent flooring failures, other prominent elements need also to be taken into consideration. Neglecting these simple yet essential factors could severely affect the desired outcome of any flooring installation.

• The material itself, which may be defective. However, a product installation may have been compromised by an installation issue such as the wrong adhesive or not enough adhesive being used, or the inappropriate application of an adhesive.

• Environmental issues may cause failures. The substrate may be at fault having high moisture vapour emissions and, with it, high alkalinity that can cause the installation to fail or adhesive to emulsify and squeeze through the surface or joints.

• Maintenance can actually create floor failures if not performed with enough regularity and if the wrong materials are used that aren’t conducive to maintaining the appearance of the flooring material and that may cause damage.

• Usage – the functionality required by a floor type is critical. Flooring needs will differ from one office environment to another. An open plan office using tables and chairs that are constantly being moved about in the space will subject the flooring specified to various unique activities, e.g. a carpet installed in this space may be subjected to activities involving crossing over the seams that can damage them if they are not manufactured for hard-wearing areas.

• Specification or selection of a product needs to be carefully considered, as flaws in this process could result in decreased performance and an appearance that doesn’t fulfil expectations.

• Care should be taken not to be over-zealous in representing a product when it is being sold. Words can’t make promises the flooring material cannot be expected to keep.

• Ignorance is another recurring reason for floor failures. Just because a product is being represented as a perfect solution or choice for a particular application doesn’t necessarily mean it will actually perform as expected. In other words, knowledge on the capabilities of a product is imperative.

• Always follow manufacturer recommendations and set standards of installation.

The above factors are by no means an exhaustive list when considering the success of a flooring installation, but offer a solid foundation from which to work in order to minimise or prevent those dreaded flooring failures.

Acknowledgement and thanks are given to Wagner Meters for their article “Moisture Testing and Protect the Installation” on http://aciernocompany.com/publications, along with other material sourced from this website, for the information contained in this article.

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