What Types of Substrates Can Epoxy Be Applied Over?
Epoxy floors have properties that have lots of great advantages for a variety of industries including food processing, commercial kitchens, chemical processing, and warehousing. Their smooth and seamless flooring make them ideal for enduring heavy vehicle traffic and for cleaning that does not allow the accumulation of dirt and bacteria. They also come in different varieties each with their own special properties and aesthetic qualities. So how do you know if an epoxy system will work in your facility? One of the first things you should consider is whether your substrate is in proper condition to allow the epoxy to adhere to it.
Epoxy floors work best when the substrate is hard, typically 3500 psi or greater, and properly leveled concrete but often epoxy can be used in restoration projects when that is not the case. If the concrete is rough and uneven it will not bind to the epoxy which, causes immediate failures in the flooring system such as bubbles and pinholes. When epoxy is applied on rough and uneven concrete it takes a lot of material for the surface to become even. In the long term this will cause the epoxy to chip and come up in chunks. Depending on your concrete placement, whether it is slab-on-grade or an elevated slab, you may also need a vapor barrier to prevent hydrostatic pressure problems (to learn more about hydrostatic pressure check out my blog post). The age of the concrete will also be a major factor to consider as fresh or “green” concrete, less than 30 days old, will need a primer prior to installation. No matter the age of the concrete, the flooring installation expert will want to check the moisture and strength of the concrete (to learn more about concrete testing methods check out my blog post).
Sometimes flooring experts will try and apply epoxy onto wood floors. At first it will look great however, that will not last long. Wood is a flexible material that has a tendency to expand and contract with differences in temperature and humidity. Epoxy cannot contract and expand with the wood so it splits and cracks very quickly. If your facility has a wood floor it is highly recommended that you either replace it with concrete or you use an elastomer as a base coat to increase the floor’s expansion coefficient. By using an elastomer as the base coat you will create a transition between the wood and epoxy thereby, decreasing the rate of expansion the epoxy endures.
Marble works as a substrate but it is imperative that your epoxy flooring expert understands how to prepare it. If the surface is not properly ground, to remove the polish and seal, than the epoxy will have nothing to bind to. In addition to the mechanical bonding, a primer should be used to chemically penetrate the marble.
Terrazzo presents similar problems to marble in that surface preparation is key. The surface needs to be ground so that the surface is scratched up enough to allow the epoxy to mechanically bond. Also, any existing sealers will want to be removed so that the epoxy bonds to the substrate instead of sitting on top of it. Terrazzo is a composite material made up of various materials such as cement, stone, and limestone so you will want to consult your flooring expert to make sure the epoxy is strong enough to bond with all of the materials. In particular, stone is notorious for being a difficult material to bond. Any cracks or pores in the terrazzo will need to be filled and if you have an old, worn-down floor you will want to make sure your flooring expert has the attention to detail necessary to adequately prepare it.
It is not recommended to apply epoxy directly on ceramic or quarry tile, as it is very brittle, however, it can readily be applied as long as you first put down a urethane cement base coat and perform proper surface preparation. The first thing that needs to be done is to make sure the ceramic or quarry tile is still bonded to the substrate underneath. The epoxy will only last as long as the tile is bonded to the substrate underneath so any loose or cracked tiles should be removed. It is also important to use an adequate cement urethane product to aid in bonding and prevent the joints from coming through on the finished epoxy. Do not forget that the epoxy top coat will only be as level as the cement urethane top coat is so make sure the substrate has all joints and seams filled.
Vinyl tile presents its own unique set of challenges. While old or loose tile should be removed, depending on the adhesive used it can be dangerous. Older installations may have been completed using cutback adhesive which, usually contains asbestos or crystalline silica. If that is the case, it will need to be professionally removed, possibly using a wet removal technique. In this situation, applying epoxy over vinyl tiles rather than removing them first may be the preferred option or you may just want to install a subfloor over the tiles rather than sanding the adhesive. This decision is best left up to a resinous flooring expert.
Vinyl asbestos tiling (VAT) can present a major health hazard due to the asbestos contained within it. To safely remove VAT tile you will need a professional who will use respirators and hazard suits to observe Department of Environmental Quality procedures. The other option is using an epoxy to encapsulate the harmful asbestos particles from being released. This is a much more cost effective way of protecting your floor and your health. The first step in this process is to carefully remove and properly dispose of any loose tiles. You will want to use a thickened epoxy to make sure that the floor levels out and can withstand abrasion and puncturing so the VAT cannot be damaged and release particulates. If you are planning on installing an epoxy system over VAT it is absolutely imperative you get a resinous flooring expert.
Depending on the substrate and needs of your facility, epoxy may not be the right choice. To learn about other flooring systems check out my blogs “Cementitious urethane flooring system over tiles” and “What resin flooring options are available for the food and beverage industry?.”