Dealing with Cutback Adhesive

With the resilient flooring industry shifting to more and more vinyl backed products, dealing with old cutback adhesive residue can become an issue. The issue at hand is that the plasticizers in the vinyl migrate down through and attack the Cutback Adhesive which softens it and then the cutback starts migrating up, causing staining in the vinyl flooring. Cutback Adhesive residue will also eventually bleed up through a felt-backed flooring product as well. There are adhesive bonding issues when going over cutback adhesive as well. 

Most cases, the issues arise with Cutback Adhesive over concrete. If the Cutback Adhesive is on a wood underlayment you may remove the underlayment or cover the Cutback Adhesive with a layer of plastic or felt paper (not roofing felt) then install new underlayment. The felt or plastic keeps the tack from the adhesive sticking and releasing from the underlayment causing a popping sound under the underlayment. 

Other issues associated with Cutback Adhesive are:

  • Hardwood and some Vinyl Adhesives do not adhere to the Cutback Adhesive 
  • Old Cutback Adhesive can contain asbestos

Then comes the age old question, “How do I deal with the Cutback Adhesive?”

There are options. 

  • If the cutback does not contain asbestos, you may grind or even shot blast the adhesive away. Shot blasting then requires a self leveling compound to smooth out the rough subflooring.
  • You can patch or self level over the Cutback Adhesive using a cementious compound. Please note, some manufacturers require a 1/8” application of cementious compound to prevent bleeding. 
  • Mapei Self Leveling
    • When self leveling over cutback here are the general rules 
      • Remove excessive adhesive until you have “residual” adhesive left.
      • Prime with a primer designed for this application like MAPEI’s Primer T
      • Install a self leveler that go over a floor that has not been mechanically profile. MAPEI’s Ultraplan Easy is an example of this type of self leveling underlayment.
  • Mapei Patching Compounds Planiprep SC and Planipatch
    • You should achieve complete coverage and that will leave a “new” porous substrate to glue to. 
    • Please note; many installers just skim coat Ardex Feather Finish over the Cutback Adhesive residue. This is what Ardex says; the existing adhesive also must be tested to verify that it does not interact with the new flooring adhesive, and the new flooring must be tested to ensure it is not susceptible to bleed through of the existing adhesive. If adhesive interaction and/or migration are a concern, install an ARDEX self-leveling material such as ARDEX K 15 Premium Self-Leveling Underlayment.
  • In many commercial renovation projects, they use liquid adhesive removers which do a great job of removing the old Cutback Adhesive, but can come back up through the slab at some point in time and eat away at the newly applied adhesive.
  • I recently discovered that JJ Haines sells a product called Triseal Adhesive Residue Encapsulator (item #632861 from Interface). Triseal is a light-colored, high-strength acrylic polymer compound formulated to isolate cutback and other types of old adhesive residues that would affect the bond of the new floor adhesive over concrete substrates. This is a single coat application. The key word here is residue.

You may use water based adhesives over the Triseal, but urethane Hardwood Adhesives are not recommended. For vinyl and rubber flooring, the adhesive must be able to be used dry to the touch. If the vinyl or rubber flooring is set into the adhesive wet, the adhesive will not dry out. The Triseal cannot absorb the adhesive moisture and the vinyl or rubber will not absorb the adhesive moisture. The adhesive will remain wet for a long period of time leading to indentation and possibly adhesive bleeding. Triseal blocks the migration of the plasticizers to prevent vinyl staining. 

Below are some recommendations for installing different categories of flooring over Cutback Adhesive:

Vinyl Composition Tile

  • Armstrong VCT Adhesives may go directly over Cutback Adhesive. Existing adhesives must be left so that no ridges or puddles are evident and what remains is a thin, smooth film. 
  • Mapei ECO 711VCT Adhesive must have the adhesive removed or covered. Can prime with Mapei Primer T, then use ECO 711.
  • Mapei ECO 611 can direct bond to cutback

Many other VCT manufacturers recommend that the adhesive be removed or covered. 

Luxury Vinyl Tile (Glue Down & Floating)

  • Glue down – LVT has a vinyl backing, which cannot come in contact with the Cutback Adhesive. The Cutback Adhesive could be covered with a cementious patch or self leveler, or use the Triseal and an adhesive for LVT that can be used dry to the touch.
  • Floating LVT – again, the Cutback Adhesive could be covered with a cementious patch or self leveler, or use the Triseal and let dry and then float the LVT.

Engineered Hardwood (Glue Down & Floating)

  • Hardwood Adhesives will not adhere to Cutback Adhesive. The Cutback Adhesive could be covered with a cementious patch or self leveler and then use either a resin base or urethane adhesive. If using the Triseal, the only Hardwood Adhesive I would use would be DriTac 6200 because it can be used dry to the touch. Using other water/resin based adhesives, the wood is placed into the wet adhesive. Over the Triseal, the wood must absorb all the moisture from the adhesive, which could lead to cupping.

Vinyl/Linoleum Sheet & Tile

  • Glue down – vinyl backings cannot come in contact with the Cutback Adhesive. The Cutback Adhesive can be covered with a cementious patch or self leveler, or use the Triseal and an adhesive for vinyl that can be used dry to the touch. 

Rubber Flooring

  • The Cutback Adhesive can be covered with a cementious patch or self leveler, or use the Triseal and an adhesive designed for non-porous substrates.

Carpet (Stretch & Glue down) 

  • The Cutback Adhesive can be covered with a cementious patch or self leveler, or use the Triseal and an adhesive designed for non-porous substrates. 

Earlier, I spoke about the use of “Adhesive Removers” and resilient flooring. If you are doing any kind of renovation work you want to start asking questions about what kind of flooring was down previously and how was it removed?

Adhesive Removers are not recommended or endorsed by the Resilient Floor Covering Industry. RFCI states; These products may leave a solvent residue within the sub-floor that can adversely affect the new adhesive or floor covering. Thus, the warranties provided by the manufacturers of new floor covering materials will not cover instances where subfloor conditions damage their products or effect their installation”. It does not matter if they are solvent, citrus, or soy based, these products are not recommended. Skim coating over a slab where these products have been used will not stop these products. The Adhesive Remover products can be absorbed into the subfloor and migrate up at some later point in time and eat away at the new adhesive you just installed. Remember, if you accept the slab, you accept responsibility. You need to ask questions before proceeding. 

Mapei does have a system for encapsulating the Adhesive Remover products: 

  • First, the slab must be cleaned using Mapei Planiprep SA which is a scouring agent that chemically etches the concrete for the next step. 
  • Second, the slab is then treated with Planiprep ET. Planiprep ET is a penetrating epoxy subfloor treatment that penetrates deeply into the concrete and strengthening and creating a suitable surface for application of all Mapei adhesives that are approved for use on non-porous substrates. 
  • If the slab would need smoothed out, prime the Planiprep ET with Mapei Primer T and then skim coat over the Primer T.

The Mapei system above provides subfloor moisture control for concrete slabs up to 12-lbs. Calcium Chloride and 90% Relative Humidity without the need for shot blasting the concrete.

 

Tim McAdoo Author Box