“Dry set” or “pressure sensitive” adhesive is the most common choice for VCT, but other types of resilient tile like solid vinyl or rubber may be better with a “wet set.”


9 x 9 size tiles were not the only ones containing asbestos. Many tile and sheet goods floors and adhesives installed before 1992 should be tested if you are not sure.

I get a lot of questions about resilient flooring from you, my readers, from people who find me on my website FlooringAnswers.com, from students in my seminars and just in the course of conversation when people find out I am in the floor covering business. Here are some that are specific to installation that I though you’d find of interest.

Q: I have to do a job where 12” x 12” resilient tile is down that was installed around 1990.  My customer is worried about asbestos and wants me to go over it with new VCT instead of ripping up the tile. Is it true that only 9” x 9” tile contained asbestos? When did they stop making it? How can I tell?

A: Both 9” x 9” and 12” x 12” tile contained asbestos; don’t make that common assumption about 9” x 9” tile.  Asbestos was also contained in tiles of other sizes, in backings on a lot of sheet goods and many adhesives. Many of those floors are still in use 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 because many local and state laws prohibit removal except by certified abatement contractors.

There is a lot of misinformation about the dates with regard to Asbestos floors. The Federal law banning asbestos building materials was passed in the late 1970s, BUT the products could still be manufactured until 1990 and sold until 1992. The actual language from the law says: “Manufacture, importation and processing must cease by August 27, 1990” and “The ban on distribution in commerce …will become effective on August 25, 1992.” Most manufacturers stopped using asbestos in floor coverings well before these dates but it was still legal to sell them so when dealing with a floor installed in 1993 or before, there is a chance that it contains asbestos.  The only way to tell is to have the tile, sheet goods and/or adhesive tested by an independent lab.

To test this plank solid vinyl floor tile for shrinkage, use the appropriate ASTM test method, but also look at variables like temperature at the time of installation and the type of adhesive that was used.



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. These materials have become popular because of their unique look and because of the “green” attributes of cork, which is “rapidly renewable” and “recycled.” I have seen products claiming to be 60% cork; true when calculated by the overall volume but by weight they are less than 10% cork because cork is lighter than rubber.  US Green Building Council “LEED” standards call for “recycled” or “rapidly renewable” content to be calculated by weight, not volume.  So the proper term should be Rubber-Cork, which is rubber flooring with cork in it. Not the other way around, which is good news for installers who get nervous about cork.

Several products being marketed with cork content are said to have added slip resistance. This is technically correct since cork swells slightly when it’s wet, providing extra grip. However, if left unfinished the cork can get dirty faster than the rubber, so most rubber-cork products are coated with a floor finish after being installed, just like other resilient floors, meaning that in actual use the slip resistance is no different than any other resilient floor with floor finish on it.  As far as installation, rubber-cork floors get 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.  Then again, if you were installing on a wall, you probably would use contact.

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. In my January 2011 “Let’s Talk Resilient” column on vinyl tile, I pointed out that  “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 to refer to the manufacturer’s literature and see which standard their product is manufactured to.  Is it VCT or SVT?  From there, you can do testing on the actual tile for dimensional stability, size, squareness and so on to see 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 problem, which laboratory testing for dimensional stability can detect.  Otherwise, 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.

Two can be the wrong adhesive, like 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 on a concrete slab where excess moisture and alkalinity are present – as we have covered many times here. Another substrate issue is an overly porous substrate where the water in the adhesive is absorbed and there is no holding power.  This could be on a gypsum underlayment that was not primed or over porous patching compound or concrete that was not properly mixed.

Rubber-cork tile, often incorrectly called cork-rubber tile, is installed like a rubber floor, usually with a “wet set” adhesive, and not with contact adhesive like a traditional cork floor.



Q: I hear terms like “wet set” and “dry” resilient floor adhesives ad recently someone told me I have to lay into a “tacky” set adhesive. What’s it all about?  

A: “Dry” set adhesives, also known as “pressure sensitive” have long been a preferred product for resilient floor installers and are most often used on Vinyl Composition Tile (VCT), although there are other products also being installed this way.  The adhesive is spread and allowed to completely dry – this can take 45 minutes to an hour depending on temperature and humidity.  The adhesive will be very “sticky” and clear when ready and if you touch it with a finger there will be no transfer.  The down side of this method is a long open time waiting for the adhesive to be ready and the inability to shift tiles once they are set into adhesive. The up side is that once it’s ready there is a very long working time for the installer to lay the floor – often many hours.

Also, the installer can work on top of the newly installed floor without fear of shifting material, adhesive oozing between the joints or indentations from kneeling on the floor. “Wet” adhesives tend to be a harder setting and stronger bonding method and are often used for rubber, solid vinyl, linoleum and other products where a hard set and strong bond are preferred.  The adhesive is spread, and after a short open time (typically 10-15 minutes) to allow some of the water to “flash off,” the material is set into adhesive while still wet. If you touch the adhesive and get a “smudge” on your finger, then it is still wet. The advantage of working with wet adhesive, in addition to the bonding characteristics, are being able to move flooring material and even pick it back up to get things set properly.  The down side is that they may not work well on non-porous substrates and only small areas can be done at a time.  Also, one needs to take care if working on top of flooring set into wet adhesive.  You can prevent shifting, oozing or denting of the material by working backwards so you never are on top of the new floor or using a board to kneel on.

“Tacky” adhesives are increasingly being used as an alternative to wet set adhesive because they still have a fairly strong bond but are not quite as sensitive as a true wet set and tend to work better over less porous substrates. You could call it a modified wet set. After spreading, there is a specific open time that is usually longer than a wet set - typically 30 minutes or so. When you touch the adhesive, a “smudge” means it’s not ready and no transfer at all means it’s been too long.  If you touch and see lines on your finger that follow the lines from the adhesive trowel, the adhesive is ready. I’d recommend that the first time you do a floor this way that you call the adhesive and/or flooring manufacturer, tell them exactly what you are installing and over what, and get some advice on how to best handle it.

Q: After many years installing I have been thinking of moving off my knees. A friend suggested getting certified as an inspector.  How can I do that?

A: The term “Inspector Certification” gets people talking and not everyone agrees with what “certified” means or if there is any value to a “certification.”  I agree that what is most important is what you know, and your ability to provide unbiased information in an easy to understand report of findings.  If you are good, you will have work as an inspector. That being said, there are some excellent training certification programs being rolled out in the industry that I recommend if you are serious about inspecting.  If you are working as an installer now, start with the resilient flooring manufacturer’s installer training programs.  The resilient industry still does a very good job in that regard. I’d also recommend learning how to do concrete moisture testing, since so many floor covering failures are related to moisture. Learn the Calcium Chloride test (ASTM F 1869) and the Relative humidity Test (ASTM F 2170).  Once you have some experience, the International Concrete Repair Institute (ICRI) offers a “hands on” certification for moisture testing technicians.

Finally, the most intensive inspector training and certification comes from The Clean Trust, formerly IICRC. Well known for their Industry Standard certification programs for carpet and upholstery clearers, smoke, water damage and mold remediation, The Clean Trust has introduced a complete program of certifications for hard surface floor covering maintenance technicians and inspectors in ceramic tile, stone/marble, wood/laminate and resilient flooring.  The prerequisite for the inspector certifications is the The Clean Trust “Introduction to Substrate/Subfloor Inspections” (ISSI) class, which covers issues related to wood and concrete including moisture testing.  The Clean Trust is a 30-year-old non-profit, volunteer operated certification body and is an ANSI Accredited Standards Development Organization (SDO). You can find more information at www.iicrc.org/courses.

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 “Resilient Q&A column!