Installation Q and A

I get a lot of questions about floorcovering installation from customers, friends and readers, during continuing education seminars and in the course of conversation when people find out I am in the floorcovering business. I like to accumulate those questions and share them from time to time here in Coverings.

Q: I’m installing plywood underlayment in a large, rectangular room. Is there a specific pattern that it should be laid in? For example, should it be laid north to south (with the boards going the long way) or east to west (across the width)?

Christopher Capobianco

Christopher Capobianco

A: The rule is that if there is an existing plywood subfloor, install the underlayment perpendicular to the existing plywood. Other rules are to stagger the joints six to 12 inches so you don’t have four corners meeting. Place the fasteners in a pattern of three to four inches on the seams and five to six inches throughout the rest of the boards. I prefer underlayment staples over any other fastener. Underlayment nails would be my second choice, but never screws because they tend to “countersink” so they’re more likely to telegraph, (be visible) through the new floorcovering, especially resilient flooring. Make sure the fastener length is no longer than the combined thickness of the new underlayment and the existing subfloor. If your fasteners are too long, they go into air space beneath the subfloor, making a structurally weaker system.

Q: I have to do a job where 12-by-12 resilient tile is down that was installed around 1990. We are concerned about asbestos. Is it true that only nine-by-nine-inch tile contained asbestos? When did they stop making it? How can I tell?

A: Asbestos containing tile came in 9- by 9-inch, 12- by 12-inch and other sizes. The products were sold as asphalt tile or vinyl asbestos tile (VAT). Asbestos was also used in backings of sheet flooring and in some adhesives. Many of those floorcoverings are still in service today so you may have to answer these questions, and be asked to deal with the old floors. It is not a good idea to tear them up unless you are sure they do not contain asbestos. In the United States, asbestos-containing products could still be manufactured until 1990 and sold until 1992. Much of that production was shipped to Canada, so if you are not sure, have the material tested by a lab.

Q: I am bidding on a “cork-rubber” tile job. What is this product? Is the same as rubber-cork? Is it installed like cork or like rubber?

A: There are a number of products that mix rubber and cork, and there are some very confusing marketing terms being tossed around. I have seen products claiming to be 60 percent cork; true when calculated by the overall volume but by weight they are less than 10 percent cork. So the proper term should be rubber-cork; rubber flooring with cork in it. It’s installed like a rubber floor, usually with a wet-set adhesive that is spread on the floor, not by using contact adhesive as you would on cork tile.

Q (From an inspector): I have to inspect a luxury vinyl plank floor that is gapping. What ASTM standards apply to these products? Is it shrinking tile or an installation related failure?

A: First, let’s get our terminology right here. Luxury vinyl tile (LVT) is not a separate category, it’s a marketing term. There are only two ASTM standard specifications in the category of vinyl tile – F 1066 Vinyl Composition Floor Tile (VCT) and F1700 Solid Vinyl Floor Tile (SVT). So the answer to the first question is, refer to the manufacturer’s literature and see which standard their product is manufactured to. Is is VCT or SVT? From there, follow the standards for testing on the actual tile for dimensional stability, size and squareness to determine if the material is up to standard.

The answer to the second question is “maybe.” If everything is done by the book and the tile shrinks, it could be a manufacturing defect, which laboratory testing for dimensional stability can detect. More commonly, I have seen three different causes for vinyl plank gapping that are installation related.

One is temperature — if the product and/or the space is very warm at the time of installation the planks can “grow” or be stretched during installation, just as I’ve seen in vinyl cove base and vinyl edgings. When the building cools to normal “in use” conditions, vinyl will relax back to its original size, creating gaps at the ends.

Second can be the wrong adhesive, such as when VCT adhesive is used on SVT and there is not enough holding power. The edges can curl or the tile develops gaps.

The third gapping scenario I have seen is substrate related. Adhesive can break down over a concrete slab where excess moisture and alkalinity are present — as we have covered many times here.

Another issue is overly porous substrates where the water in the adhesive is absorbed and there is insufficient holding power. This could be gypsum underlayment that was not primed; cement based patching compound that was not properly mixed; or a bad concrete slab.

Q: What’s the preferred method for testing moisture in
concrete? Calcium-chloride or relative-humidity testing?

A: ASTM F 2170, the relative-humidity probe test was published in 2002 and is generally accepted and preferred by most manufacturers. The calcium-chloride test has been around for more than 50 years and is now known as ASTM F1869. It only measures moisture emissions from the surface of the concrete. It’s not as good a predictor of future moisture emissions as the ASTM F 2170 method that measures moisture inside the slab using a probe placed in a hole drilled in the concrete. If you do use the F1869 calcium-chloride test, follow the procedure. It’s done wrong very frequently! It’s important to grind the slab clean and follow the proper waiting time after grinding. Temperature and humidity at the time of testing are also critical.

More questions? Please feel free to contact me — I’d enjoy hearing from you and helping point you in the right direction for unanswered questions, and maybe even use your questions and answers in my next Q&A column!

Christopher Capobianco has been in the floor covering industry since the 1970s in various roles including retail and commercial sales, technical support, consulting, journalism, education and
volunteer work. He currently is part of the sales team for Spartan Surfaces in New York City. You can reach him via [email protected]

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