As an expert in providing heat welding help and training, I am often brought into a commercial flooring project when a problem arises on a heat welded resilient floor. Usually, I am asked to visit a facility when there is a noticeable problem with heat welded flooring seams post installation and after the customer has moved into the space.
Typical visible issues, with heat weld floor joints, range from subtle floor seam gaps to completely split seams on, what should be, a seamless resilient floor. Openings in the heat weld seams can cause major problems because it allows bacteria and other germs to hunker down in flooring cracks and crevices. An otherwise sterile environment might be compromised when a floor’s heat weld seams fail. In addition, the compromised floor will take on a dull, dingy appearance because of the dirt deposits that get trapped in the faulty seams during floor cleaning. These are all great reasons to master the fine art of heat welding, or hire someone who is a master at heat welding resilient flooring seams, before completing a large commercial or institutional flooring project.
Widely used in hospitals and other health care facilities, heat welded resilient flooring hermetically seals PVC and non-PVC sheet or linoleum flooring in sterile operating rooms, laboratories and critical patient care spaces so it’s best to get the weld rods thermally fused correctly the first time because making repairs around a busy medical facility schedule requires more time and interrupts the customer’s business. When the process is executed correctly resulting in no gaps in the resulting monolithic flooring surface, a sterile floor can be achieved when the seams are properly heat welded.
Heat welding is a straightforward process that requires a great deal of precision and practice. When equipped with the correct tools, mastering the art of heat welding seams on a commercial vinyl floor is within reach of most quality flooring installers.
Critical Rules to Mastering the Fine Art of Heat Welding:
1. Consistently work through heat welding procedures, in order and in accordance with each flooring manufacturer’s heat weld specifications. Instructions for tools, temperature and rod size vary with each flooring brand and model. This means that you must read the directions on each and every heat weld job!
2. Practice heat welding technique on scraps of flooring material, specific to the job on which you are working, before welding seams on the installed sheet floor. Do this on-site so your technique is appropriate to the environment of your customer’s floor. All environmental factors influence the outcome when welding and trimming, including room temperature, slab temperature and humidity.
3. Cut seams NET, or slightly gapped UNIFORMLY, to accommodate an auto groover! Failure to do so will result in welded joint failure and an unhappy customer -facilities manager, building owner, etc.
4. Thermally fuse, or melt, the vinyl welding rod so it fits uniformly on each side of the seam and underneath the seam. This creates the needed strength at the welded floor joints to hold up in environments where extreme use and heavy rolling loads are common.
5. Avoid contamination and NEVER groove seams until you are ready to weld! When the time is right, center grooves on the seam line. Depth of the groove should be approximately 2/3 of the overall resilient flooring material thickness so that the finished groove provides material underneath and on both sides of the seam line for optimal fusion. Important note: If flooring manufacturer instructions indicate a different groove thickness, follow the flooring brand information.
6. Use welding gun tools that deliver the flooring manufacturer’s required temperature for fusing the rod to their flooring. (reminder: Read flooring installation instructions!) The throat of the heat weld speed nozzle is where the weld rod melts. It is critical that the speed nozzle be the correct diameter for the welding rod and the nozzle’s throat, behind the nozzle’s rod feed port, should be a little smaller than the width of the groove. This will keep the heat from the welding gun focused in the groove and will avoid “glazing” the flooring on each side of the seam. “Glazing” makes the flooring at the seam appear to be glossier than the rest of the floor. See rule number 2 – Practice on a scrap flooring so that you marry YOUR speed with the temperature of welding gun; you should visibly see a nice “wash” or slightly distorted area at the juncture of the welded rod with the flooring on each side of the seam as you weld. If you do not see this wash, the rod can be easily pulled from the groove.
7. Trim welded seams with a sharp spatula knife designed for skiving welded seams or similar tools engineered for the same purpose. Use a trim plate to take the bulk of the excess rod off. THEN WAIT! Wait for at least 30-minutes before making the finish trim. Welding rod has a natural tendency to shrink as it cools. With too short of a wait time, this contraction will leave a slight concave at the trimmed rod eventually becoming a haven for holding dirt, so have patience and wait.
If you love boring flooring like I do, you might want to learn some history about the fine art of heat welding flooring seams…
Heat welding made its debut in 1960s and 1970s in the United States with welded vinyl sheet flooring and welding rods produced by a, then, little European company known as Tarkett. The goal for heat welded seams – to position PVC sheet flooring so it could compete with other “seamless” floors in the marketplace such as epoxy, poured polyurethane and terrazzo.
Heat welded PVC flooring was embraced by healthcare facilities where there was a need for a germ-free environment in hospital treatment and patient rooms.
In the early 1980s, Armstrong introduced a line of homogeneous sheet floor, Medintech, developed as an easy-to-clean, long-lasting commercial flooring solution that required heat welding at the sheet seams and at coved joints for a seamless finished floor. This monolithic, uninterrupted floor provided superior infection control to meet the needs of medical, institutional and technical facilities, for which the product was named. This hard working flooring found great success in the 1980s and continues to evolve and hold strong through the start of the new millenium. Interesting fact – When Medintech was first introduced, Armstrong would only sell this new line of flooring to suppliers that participated in and passed their heat welding certification course.
Forty years after it’s introduction into the flooring market, welded seams on resilient sheet flooring continues to be an ideal solution for the growing number of healthcare and senior living facilities throughout the United States of America and worldwide.
Today, most commercial flooring makers, including Tarkett, Armstrong, Mannington, Roppe, UPO, Altro, Forbo, Gerflor, Shaw, Parterre, Mohawk, CBC America, Lonseal and more, make vinyl, linoleum and other sheet flooring goods that require the expertise of flooring installers to master the fine art of heat welding flooring seams.