Should I test for moisture in the substrate before installing any flooring?

Yes. All flooring manufacturers recommend some type of moisture testing and standards that must be met before the installation of their products. For example, resilient flooring and carpet manufacturers recommend the calcium chloride test. Wood manufacturers may recommend other means of testing. If recommended limits are not met, failure of the flooring installation may result. At this point, the flooring and the adhesive manufacturer are no longer responsible for the failure of their product due to moisture.

Keep in mind that moisture testing cannot predict long-term moisture conditions. Tests are only indicators of moisture conditions at the time they are run.

What is the most common moisture test method?

The calcium chloride test kit, which is a quantitative test, is the method recommended by most, if not all, resilient flooring manufacturers. This test, now an industry standard, ASTM F-1869, must be run in all areas where there is a concern for moisture. Calcium chloride tests are normally run for 60-72 hours depending upon the manufacturer. The results are expressed in terms of pounds per 1000 square feet per 24 hours. To install resilient flooring, the results must be 3 to 5 pounds/1000 sq. ft/24 hours or whatever the flooring manufacturer recommends. Calcium chloride test kits can usually be purchased from flooring and sundry supply distributors.

When installing wood underlayments, what precautions should be taken?

Use only the underlayment boards recommended by the flooring manufacturer for the type of flooring being installed. Wood underlayments must be acclimated by placing them in the area where they will be installed for at least 24 hours before they are installed. Panels should be lightly butted and not filled or flashed unless the board manufacturer specifically recommends filling the joints. Differences in thickness of wood panels should be corrected by sanding. If not acclimated, the boards will expand and contract at rates different from the subfloor over which they are installed and this will increase the risk of tunneling and/or ridging. Filling or flashing joints between panels may also increase the tunneling and/or ridging over these joints and especially in conjunction with lack of acclimation.

Why should I test for alkali and what should I do if it measures above 9?

pH is the symbol used in conjunction with a number to indicate acidity or alkalinity. The numbers on the pH scale are 1 to 14 with 7 being neutral. Below 7 is acid while above 7 is alkaline. Testing is done using a wide range pH tape and distilled water. Alkali testing material is now found in all calcium chloride test kits. The allowable pH range for the installation of flooring is normally between 5 and 9. Flooring adhesives are designed to be alkali resistant up to a pH of 9. Above 9, the alkali becomes excessive and can actually burn your skin and start to dissolve concrete aggregate. Alkali comes to the surface of concrete with water and once the water evaporates, it leaves the alkali salt residue. If alkali is too high, it is best to use clear water or soda water to clean the surface, allow the concrete to dry, and retest. Traditionally, acids have been used to "neutralize" the concrete, but acids may leave a residue which is as detrimental to the flooring installation as the alkali. Excessive alkali may cause white deposits at tile joints and when excessive, may actually corrode or burn the edges of the tile. It can build up under flooring causing bumps to occur. Alkali may eat away at adhesive causing failure of the bond and damage to the flooring itself. Alkali can also cause dusting of the concrete surface. Alkali testing can only show the amount of alkalinity at the time the test is run and cannot be used to predict long-term readings.

What is meant by grade level?

Grade level, when speaking of resilient flooring, is where the flooring will be installed in relation to the ground around the building. A suspended or above-grade subfloor is one which has a minimum of 18" of well-ventilated air space beneath it. Normally, this would be over the basement, but in some homes, this could be over a crawl space. An on-grade subfloor is one which is in direct contact with the ground or over a fill which is in direct contact with the ground. A below-grade subfloor is one which is partially or completely below the ground surrounding the building and is in direct contact with the ground or over fill which is in direct contact with the ground.

Can I install a new floor covering over old adhesive residue?

When installing new resilient tile,  tile adhesives can be used over old adhesive residue as long as the adhesive residue has no ridges or puddles evident and what remains is a thin, smooth film. When installing vinyl-backed sheet flooring, we recommend the removal of 100% of adhesive residue. With all other floors, the adhesive must be removed so 80% of the overall area of the original substrate is exposed. However, if the adhesive residue is asphalt cutback, as an alternative to removal, you can use a cementitious underlayment  mixed with water.

Can I use an adhesive remover to remove adhesive residue from a subfloor before installing a new resilient floor?

Many adhesive removal products contain solvents that leave a residue within the subfloor. This residue can negatively affect the new adhesive and bleed through the new floor covering. Floor covering warranties do not cover instances where existing subfloor conditions cause damage to the flooring or installation failure.

I have existing adhesive residue on my substrate and would like to install a new felt-back sheet flooring. Why must 80% of the original substrate be showing through?

All flooring expands and contracts. When a new flooring is installed over existing adhesive residue, it expands and contracts as usual, and can actually move the existing adhesive residue. Depending on the bond of the adhesive residue to the substrate, the flooring may pull away from walls and apart at seams.

Why shouldn't you install flooring directly over paint or other coatings on a subfloor?

The bond of the flooring to the subfloor is only as good as what you bond to. If you bond to old paint, sealers, polish, or other foreign matter, you are dependent upon the bond of that material to the subfloor to hold the flooring in place. Since we cannot determine how strong that bond may be, it is best to bond directly to the substrate.

What is meant by porous and nonporous in relation to subfloors?

A porous substrate is one which is capable of absorbing water or liquid, such as concrete or wood. Liquid beads up on the surface of nonporous substrates which are typically existing resilient flooring. If there is any doubt as to porosity of the substrate, it can be checked easily by placing a few drops of water on the surface. If the water is quickly absorbed, the substrate is porous. If the water beads up and remains on the surface, the substrate is nonporous.

What is lightweight concrete?

Lightweight concrete is concrete made with lightweight aggregate (shales, clays, pumice, etc.) or with the addition of chemicals which foam and produce air spaces in the concrete as it hardens. This should not be confused with products which are manufactured and used as floor fills and toppings.

What is a sleeper-constructed subfloor and why can’t I install flooring over this?

This is a wood subfloor installed over an existing concrete subfloor on or below grade without 18" of well ventilated air space. Concrete on or below grade will have some moisture in it due to its proximity to the ground. When there is not enough ventilation, moisture will build up causing not only installation failure, but possible rotting of the wood. Since suspended concrete today may contain excess water due to steel pan construction, wood over concrete on any grade level is not recommended.

What is APA trademarked plywood?

APA trademarked plywood is plywood underlayment approved as suitable for the installation of resilient flooring by APA - The Engineered Wood Association.
 
 

What is meant by pot life?

Pot life is the amount of time a product, which must be mixed, remains workable in the original mixing container. This is generally applicable to two-part epoxies and powder underlayments.

Why do flooring manufacturers recommend not smoothing true expansion joints with any type of underlayment product?

True expansion joints are those placed between separate pours of concrete. These joints are designed to absorb the movement of the concrete and are normally filled with elastomeric fillers which absorb the movement of the separate pieces of concrete. If an underlayment is placed across or in these joints, the movement of the concrete will cause the underlayment to break up or will push it out of the joint. Additionally, any flooring placed across these joints will break or crack with the movement of the concrete. Expansion joint covers, which are designed to span these joints, should be used in these areas.

What does it mean when a specification states that commercial and institutional environments must have a compressive strength of 3,500 psi for floor fills, patches, and toppings?

Compressive strength is expressed in pounds per square inch. This means the material can withstand 3,500 pounds per square inch without breaking. Because

of the concentrated floor loads that exist in commercial and institutional environments, concrete must be higher in compressive strength than for residential applications.

I am installing over existing vinyl composition tile. Can I float the existing tile with a powdered underlayment product?

We do not recommend covering an existing vinyl composition tile installation with a powdered underlayment. The risk is in the existing tile breaking loose from the substrate. However, powdered underlayments are recommended for patching and repairing small areas of damage or broken tile in an existing VCT installation.

What is an embossing leveler and why do I need to use one?

An embossing leveler is a specially designed material for leveling embossing in existing resilient flooring before the installation of a new flooring. Embossing is the textured-like design in a floor. If this design is not smoothed and leveled, it will show through the new flooring installation.

Does the use of an embossing leveler render an existing resilient flooring porous?

No. Embossing leveler fills the embossing and levels it with the surface of the flooring. It does not cover the surface of the existing resilient flooring. Therefore, the surface remains nonporous and directions for installation over nonporous surfaces are the ones which should be used.

What is the purpose of latex when using powdered underlayments?

Whether added as a liquid or in powdered form, latex adds resiliency to the underlayment so it does not break up with a limited amount of deflection. Latex also improves the bond of the powdered underlayment to the substrate and increases flexural strength of the powdered underlayment over wood and metal substrates. The use of a latex primer on a porous substrate improves the bond of the mixed underlayment or adhesive, but does not add any additional properties to the powdered underlayment.

I used an embossing leveler over an existing resilient floor and still have bumps and ridges showing through my new flooring. Why?

You may not have completely filled in the embossing with the embossing leveler. When using an embossing leveler the product fills in the low places or embossed areas of the existing flooring. If the embossing is deep, two layers must be applied. Once the first layer is done, you need to determine if the leveler is even with the surface of the flooring. If not, then another application is required.

Why can’t I install a new tile floor over an existing tile floor in my basement?

Tile over tile is not recommended on a floor below grade. A basement is below grade and concrete below grade will almost always have moisture in it. A single layer of tile allows any moisture in the concrete to escape through tile joints. When you place new tile over existing tile, you cover the tile joints and cut off the escape route for the moisture. This traps the moisture beneath the tile and can cause loosening of the old tile as well as the new tile.

Why must sheet flooring be rolled when it is installed?

Rolling pushes the flooring down into the adhesive and flattens the adhesive ridges. This assures contact with the adhesive and also assures the adhesive ridges will not show through the finished flooring. Rolling also pushes air out from beneath the flooring between the ridges left by the trowel notches. This significantly reduces the amount of trapped air which may cause bubbles in the finished installation.

Why must all materials be conditioned before installation?

Vinyl flooring is stiff when cold, flexible when warm. Vinyl flooring that has been conditioned at the recommended room temperature has better installation characteristics. All materials expand or contract when atmospheric conditions change. In order for the flooring to expand or contract with the subfloor, it must be conditioned to the same atmospheric conditions.

How should I protect my carpet until the adhesive cures?

Traffic on a new carpet installation should be restricted for a minimum of 24-48 hours to allow proper adhesive cure. Premature traffic can cause installation failure. Exposure to water from cleaning and other sources should be restricted for a minimum of 30 days.

What is meant by open time?

Open time is the amount of time recommended by the manufacturer for the adhesive to set before it is covered with the flooring. Open time is affected by temperature, humidity, and porosity of the subfloor. Placing sheet flooring into the adhesive too soon may cause the flooring to bubble. Placing tile into the adhesive too soon may cause the tile to move and adhesive to ooze up between the tile joints.

What is meant by "working time"?

Working time for tile and engineered wood is the amount of time from when the adhesive is set until the flooring will no longer bond. Working time for sheet flooring and carpet is the amount of time from when the flooring is laid into place until all fitting and cutting must be completed. Working time is affected by temperature, humidity, and porosity of the subfloor. Placing flooring into the adhesive after the working time has passed will result in a failed installation as the flooring will not bond.

What is meant by freeze-thaw stable in relation to adhesives?

Freeze-thaw stable adhesives are not as prone to cold weather damage as other adhesives, but they must still be treated with care. They should be shipped in heated trucks and stored in above-freezing temperatures. Most freeze-thaw stable adhesives can be thawed if the temperature has not dropped below 10° F. Below that temperature, they can be damaged too badly to be used. If a product has been frozen at above 10° F, it often can be used after thawing at 72° F for 12 to 24 hours. NEVER APPLY HEAT DIRECTLY TO FROZEN PRODUCTS. Some adhesives are not affected at all by freezing. These are usually epoxies or solvent-based products. To ensure proper handling and performance, all adhesives should be stored at room temperature above 65° F for at least 24 hours before they are used.

What does the CRI Green Label mean?

A product that features the CRI Green Label identifies that product as a low VOC adhesive. Only those adhesives that do not exceed the rigid test criteria of CRI’s Indoor Air Quality Adhesive Testing Program are authorized to display the label.

The Carpet and Rug Institute (CRI) is the national trade association for the carpet and rug industry. The membership is comprised of manufacturers and suppliers representing 94% of all carpet produced in the United States.

How important is the use of the recommended trowel?

Very important - this is the most common mistake made during installation. Most flooring adhesives are applied with a notched trowel. The size of the notching is important as it controls the amount of adhesive applied. Notches which are too large spread too much adhesive. This can cause excessive indentations to show through sheet goods and trowel mark show-through or bleeding at tile joints. Using too much adhesive with some flooring can cause swelling and buckling where the adhesive is applied. Always check the adhesive label for the proper notching.

What does "dry to the touch" mean?

Dry to the touch means when you place your fingertips lightly on the adhesive ridges, no adhesive transfers to them.

I just purchased a can of adhesive, and when I opened it, I found it very thick and stringy. Is there something wrong with the adhesive?

Generally, when adhesive becomes very thick or heavy and stringy in the can, it is no longer usable. Sometimes this can occur when the adhesive is well beyond its shelf life. In a rubber-based product , the product may have been frozen and thawed. Try stirring the adhesive as in some cases one freeze-thaw cycle will not harm the product. Freezing does not hurt the bonding characteristics - just the handling characteristics. If the adhesive is trowelable after stirring and does bond the flooring, there will most likely not be any future problems.

What is meant by Next Generation?

Environmentally compatible products are being requested more frequently by customers. Our Next Generation products meet those customers’ needs. These products are formulated to be environmentally compatible, yet continue to provide the working and handling characteristics required of a floor covering adhesive. Next Generation products are:

• Either low in VOC’s (less than 150 g/l, SCAQMD) or have no VOC’s (calculated at 70(F, SCAQMD) 
• Nonflammable 
• Ammonia-free and low odor 
• Contain low or no organic solvents 
• Contain no reportable hazardous substances (as per current regulations) 

I spread tile adhesive 2 hours ago, and the recommendations say open time is 1 hour or until dry to the touch. The adhesive is still wet. Why?

If a larger notch trowel than recommended is used, too much adhesive is spread, and this will increase the amount of open time required for the adhesive to be dry to the touch. If there is moisture in the subfloor this too can cause retarded setting of the adhesive. If the controlled climate is not in use in the building where the tile is being installed, and the outdoor temperature and humidity are high, the setup time is greatly increased. This will especially happen on hot, humid summer days or rainy days. When the adhesive is spread on days like this, moisture can condense on the surface of the adhesive, severely slowing the setup.

While the use of fans to circulate air in the room may help, it is important to remember not to place the fans so the air blows directly on the adhesive. In most cases, if the adhesive has a long working time, it is possible to let the adhesive set overnight and install the tile the next morning.

What is meant by "telegraphing" or "show-through" and what causes this to occur?

Telegraphing or show-through is when the irregularities, imperfections or patterns of the substrate are visibly transmitted through the flooring. Possible causes of this are:

• Improper trowel notching was used (too large, too far apart, irregular) 
• Subfloor was not cleaned properly 
• Subfloor was not properly prepared and/or patched 
• Non recommended underlayment boards were used 
• Embossing leveler was not applied properly 
• New flooring was applied directly over heavily embossed existing flooring 

What causes a clicking/crackling sound when walking over a resilient floor?

This can occur when tile has not conformed properly to the subfloor. When flooring is installed, it is recommended you acclimate the flooring to the area in which it will be installed. It is also recommended the area be 65° F or more. These temperatures will allow tile to conform when it is laid onto the floor and pressed into place. If the installation area is cold, and/or the tile is cold, or if the substrate is not flat, the tile will not conform properly. When you walk on tile, you are pushing it down into the adhesive and, if the tile is not conformed, you are pushing it into contact with the adhesive which causes the clicking/crackling sound. To fix this you can usually heat the area for at least a day and then roll the tile using a 100 pound roller. Another cause of this type of sound is the installation of new underlayment boards over old adhesive residue. To prevent this, you can put felt over the old adhesive before installing the new boards.

What is adhesive bleeding and what causes it to occur?

Adhesive bleeding is the undesired migration of the adhesive at the joints of tile to the surface. If a black adhesive has been used, then the bleeding will appear black. If a light-colored adhesive has been used, it sometimes appears as a buildup of dirt at the joints. This can be caused by:

• The use of too much adhesive (improper trowel used) 
• Placing tile into the adhesive without waiting the recommended open time 
• Moisture migrating through the substrate 
• Installing over incompatible sealers, curing agents, asbestos encapsulants, polish residues, etc. 
• Use of solvent-based adhesive removers, paint thinner, and other solvents 
• Use of no-rinse strippers within the first two years of installation 

In order to remedy the situation, it must be determined what has caused the bleeding to occur.

What causes alkali (white deposits) at tile joints?

White, salt-like particles at tile joints are normally an indication moisture has carried alkali to the surface of the flooring. This condition is not usually noticeable in open areas where there is a lot of foot traffic but can occur under furniture and in corners where there is no traffic. Mopping with clear water will keep the alkali from building up at tile joints. Alkali can cause serious damage to flooring so all precautions should be taken before installation to make certain it will not be a problem. Testing for moisture and alkali should be done before any resilient flooring installation takes place on concrete.

Tile, installed over concrete on grade in a converted warehouse, has brownish deposits coming up between the joints. What could be the cause?

Most likely, the concrete had a metallic hardener used and due to moisture coming up through the slab, the metallic flakes are rusting. The adhesive, which probably softened due to the presence of moisture, mixes with the rust, and bleeds to the surface of the tile at the joints as a brownish deposit.

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