following-the-manufacturers-instructions-for-adhesive-and-substrate-preparation
Date
Jul 31, 2025
Substrate preparation is the foundation for your resilient flooring. Without proper substrate preparation your floor could fail or simply be unsightly. Either way you will have an unhappy customer. That is why selecting the right patching and leveling products is essential. Selecting the right adhesive for the project is equally important because it can be the difference between success and failure.
I recommend starting by reading the flooring manufacturers’ installation instructions. Keep in mind that some flooring manufacturers put their limitations in their adhesive instructions. These instructions and limitations will typically include the acclimation period, substrate moisture limitations, pH limitations and acceptable temperature and humidity ranges. Some flooring manufacturers may require a wet set or semi-wet installation with resilient flooring that would typically call for a dry set with a pressure sensitive adhesive. In these cases, the installer must follow the flooring manufacturer’s instructions even if they are not using their private label adhesive. It is not only flooring products that may have special requirements. There may be special instructions for materials such as cove base, transitions or stair treads where the bonding surface of the material will need to be cleaned with denatured alcohol or sanded to remove mold release. Proper adhesive coverage will also be required with the specified trowel or cartridge nozzle for proper bond.
Before you order material and start a project you need to ask questions about the site. If the project is in an existing building find out the age of the slab. Ask about the history of the site. Things like moisture related flooring failures, floods, and previous flooring types can all be red flags. If the building predates the ban on asbestos in flooring, you need to find out if a chemical abatement was performed to remove hot adhesive. You should also ask about any other adhesive removers that have been used that could have contaminated the substrate. If you are working over a new slab, ask about admixtures, fly ash, accelerants, curing compounds, bond breakers or hardeners that were used in the mix or on the slab. When it comes to fly ash, knowing the pH levels as well as the percentage used is critical. It should be noted that flooring, adhesive and patch manufacturers may not recommend their products over all or some of these concrete components. This vital information will provide you with much needed information regarding special precautions that may be needed.
Knowing the requirements and limitations for the flooring, cove base, stair treads, adhesives, primers, sealers, patching and leveling products or any other materials being used is essential for a successful flooring installation.
Many resilient flooring, adhesive, and patch manufacturers will refer to ASTM F710 which is essentially a guide for a successful resilient flooring installation. In my opinion, every flooring installer and contractor needs to familiarize themselves with ASTM F710 to make certain they are following the proper steps. Naturally these installation protocols will update and change to adjust to industry changes so keeping up to date is critical.
Whether you will be installing over a new or existing concrete slab both moisture and pH testing is always an important first step. For existing substrates, you should consider the age of the slab as part of your moisture test. For instance, an older slab with high substrate moisture readings, either ASTM F1860 moisture vapor emissions or ASTM F2170 in situ RH could indicate a damaged or missing under-slab vapor retarder. Most resilient flooring products and the associated adhesives require a functioning under slab vapor retarder per ASTM E1745. The requirement for an under-slab vapor retarder is also included in ASTM F710. Depending on state and local building codes and the original intended use for the building, an under-slab vapor retarder may not be required by code, so it is important to research. If the slab was poured for a garage or warehouse an under-slab vapor retarder may not be required even if they are common in that state. Also, when you are installing on a new concrete slab, knowing what admixtures, hardeners and curing compounds used is essential. If you are unfamiliar with any of these components your flooring, adhesive or patch manufacturers should be able to provide insight and guidance.
If moisture mitigation is needed selecting the right product for the project is essential. Most moisture mitigation products will have limitations. Those limitations can vary depending on the product selected. For instance, most moisture mitigation products will exclude hydrostatic pressure or other pressurized sources of moisture. Hydrostatic pressure requires an elevated moisture source. In other words, the slab will need to be below the water table. In most cases this requires the slab to be below grade. If any portion of the slab is below the surrounding grade hydrostatic pressure is possible. In large commercial buildings with flat roofs, it is not uncommon to find downspouts placed in the middle of the facility. If these downspouts become blocked or restricted rain events can create a hydrostatic head. It can even happen when elevated planters or water features are adjacent to the building. Plumbing leaks from both supply and drain lines can also provide a pressurized source of moisture. Osmotic pressure can also cause flooring failures with blisters. Many moisture mitigation adhesives and coatings will exclude slabs without functioning under-slab vapor retarders per ASTM E1745. This requires the slab to be poured directly over the vapor retarder. Some state and local building codes still allow for a granular blotter layer on top of the vapor retarder which will render it ineffective. Even worse there are some state and local governments who still do not require an under-slab vapor retarder in their building code.
Virtually every substrate that will be covered with resilient flooring will require some patching and leveling. Naturally the amount of substrate preparation will vary from site to site. Selecting the right patch or leveling product to flatten the substrate in preparation for resilient floor covering is important. Knowing the patching or leveling compound PSI requirements of the flooring manufacturer for your application will help you in your selection. You will also need to consider the moisture and pH limitations of the patching and leveling products that you select. This is particularly important if you are installing using a moisture barrier adhesive. Remember that any adhesive is only as good as what it is attached to. Using the right patch under high moisture and pH tolerant adhesives is also recommended. It should be noted that most patch and leveling manufacturers do not recommend applying their products over water-soluble adhesives. In my opinion, old adhesives should always be completely removed prior to installing new resilient flooring since you cannot depend on the integrity of the old adhesive. Spending a little more time doing substrate preparation will often save you headaches and expensive repairs or failures down the line.
Do your homework before starting any project with a flooring product you are not familiar with. If you feel the customer, designer or architect has selected a product that will not perform as desired it is your obligation as a flooring professional to advise them.
