Most design and construction specifications rely on the manufacturer's installation instructions as a base reference document, and language like "Installed per the manufacturers installation instructions" has almost become common place. Unfortunately, installation requirements vary from manufacturer to manufacturer: some requirements are incredibly vague and hard to follow, and some are so exacting it's almost impossible to get right.
We're highlighting the four main points covered in manufacturers installation requirements, to help you understand why each is so critical for a successful flooring project.
Moisture Limits and Testing
Different flooring products can handle varying levels of moisture. Most manufacturers will provide guidance as to the moisture limits of their flooring and adhesive, and require moisture testing to be carried out prior to installation, to confirm that the flooring is suitable for the site conditions.
There are two industry-recognized moisture tests: relative humidity (RH) probe testing, and the anhydrous calcium chloride test (ACC). However, the RH test has become the industry standard, and while some installation standards may still recognize the ACC test, the RH test is often preferred.
When testing subfloor moisture levels it's important to consider not just the limits of the flooring you're installing, but also the limits of all products being used - including adhesives, sealants and encapsulating skim coats. One common installation mistake is to overlook these additional components, which may have lower moisture thresholds than your flooring, so while your subfloor may be suitable for your selected carpet, the moisture levels are too high for the skim coat, which becomes the failure point for the whole install.
And while moisture testing is required, a passing test doesn't always mean you are free and clear of moisture issues.
In fact, for slab-on-grade renovation projects, moisture testing is simply a snapshot in time. In many cases these existing slabs either don't have a vapor retarder, or it's been compromised, meaning moisture in the subsoil can work its way into the slab, elevating moisture to levels outside the recommended specifications. This is a case where even if you follow the manufacturers installation instructions you could still run into flooring failure down the line.
pH Testing and Limits
The natural pH range of cement is 11-13, but once it's poured and starts to dry, it reacts with the carbon dioxide in the air and forms a layer of calcium carbonate on top - which has a pH of 9. However, if you're in a high-moisture environment, there's a risk that moisture will get into the concrete subfloor and activate the pH, causing pH levels at the surface to rise.
Most commercial flooring is warranted to withstand pH levels not exceeding 9 pH, and most manufacturers require pH testing in line with guidance set out in the ASTM F710 standard - so to prevent any issues with warranty claims down the line, make sure to test your pH levels before installation, and crucially, keep records of the pH level recorded.
A Note on ASTM F710
The ASTM F710 standard is one of the most critical standards for contractors to adhere to when carrying out floor preparation and flooring installation. Many flooring manufacturers either draw upon the standard as inspiration for their install instructions, or directly reference it as a requirement. While the standard lays out the requirements for preparing concrete subfloors to accept resilient flooring, many of the requirements are just as relevant for carpet and other flooring types.
Floor Surface Preparation
Floor preparation is often the most time-consuming part of your flooring installation. It covers everything from cleaning the surface to ensuring it's ready to accept new flooring, to taking into consideration moisture levels, pH, and the condition of the surface. The requisite floor preparation varies depending on the flooring manufacturer, as well as the install conditions.
You may need to carry out floor levelling - for example, if removing existing flooring has damaged the surface and left cracks or dents in the subfloor - and you may need to encapsulate the subfloor to isolate your new flooring and adhesives from traces of old adhesive and other chemicals left behind from previous installations.
Adhesive removal is an important part of subfloor preparation, for several reasons. Firstly, it prevents chemical incompatibility between existing adhesive and PVC backed products. Additionally, some types of flooring (such as carpet tiles with thermoplastic backings) are relatively thin, and so are prone to 'telegraphing' - where lumps and bumps from the subfloor show up through your new carpet.
When it comes to adhesive removal, manufacturer recommendations tend to be either incredibly vague, or extremely precise. For example, we've seen one manufacturer who states that "pre-existing adhesive must be 90% removed" from the subfloor prior to installing new flooring. While that sounds very clear and precise, it's extremely difficult to action: what does "90%" of trace adhesive look like? How can you tell whether you've removed 85% or 90%?
One crucial, but often overlooked, installation requirement is the bond test. Put simply, it's a test to check that your adhesive will function as expected, and adhere your flooring securely to the subfloor. The standard requirement is to carry out the bond test 24 hours ahead of your main flooring install.
This step is often missed or overlooked, but it's important to note that not carrying out a bond test can completely invalidate your flooring warranty - meaning you're not protected in the event of any problems.