Adhesive bleeding is like the gift that keeps on giving. No matter how many times you clean it up, it will keep coming back up through the tile joints over and over, again. What causes this Adhesive Bleeding? There are a few reasons that I know of.
- Excessive Subfloor Moisture – The moisture content of the concrete subfloor is higher than what the flooring adhesive can withstand and over a period of time it totally breaks the flooring adhesive down into a watery state called re-emulsification. This broken-down flooring adhesive then wicks up through the joints of the flooring and gets tracked over the floor. Solution; always run the appropriate moisture test prior to installing the flooring so you know where the concrete slab is at. You now have a reference point and if these readings change later on, it could be another issue. To fix excessive subfloor moisture, remove the existing flooring and adhesive and treat the concrete moisture issue.
- Too Large of a Trowel Notching – The installer uses to large of a trowel notch and applies more flooring adhesive than is required. Combine this with a subfloor with minimal porosity and applying a fan directly to the adhesive to force dry it. The subfloor with minimal porosity can wick no moisture away and now the adhesive must dry from the top down. But wait, we used more adhesive than necessary and we are now forced into drying it with a fan. The adhesive ridge forms a skin over the top of the adhesive. It is not totally dry throughout. It appears dry to the touch and the flooring is installed. The building becomes occupied and people begin rolling chairs and loads over the flooring. The skin over the adhesive ridge breaks and the adhesive starts seeping up through the seams, generally right beneath the rolling casters of an office chair. It usually is assumed as a moisture issue. Generally, moisture issues just don’t appear under the office chairs. They are throughout the installation.
- Chemically Abated Adhesive Residue – This one happens quite often in older buildings that are being renovated. An abatement company comes in and removes the old “asbestos” flooring and old “Cutback Adhesive” is down, which also contains asbestos fibers. The abatement company floods the floor with a liquid mastic remover. It slowly dissolves the Cutback Adhesive and it also soaks into the concrete subfloor.
The installation company comes in and installs the flooring and seals up the concrete subfloor. As time goes on the liquid mastic remover begins seeping up through the concrete and starts to break down the new adhesive that has been applied and it now starts to wick up through the joints of the new flooring. I have had calls on this when installers knew solvents were used and they thought applying a patch over the solvent ridden slab would stop the migration of the solvent back up through the concrete. The patching compound is a porous material and will not stop the migration of the solvent. There are adhesives and products that can go over “Cutback Adhesive”, but generally the key is:
- Adhesives must be left so that no ridges or puddles are evident and what remains is a thin, smooth film.
- Can be applied over old asphalt cutback adhesive residue as long as the adhesive ridges and raised residue havebeen completely removed from the subfloor with only minor stains remaining.
- Armstrong VCT Adhesives (S-515, S-525, S-700 or S-750) may go over “Cutback Adhesive” as long as the Adhesives must be left so that no ridges or puddles are evident and what remains is a thin, smooth film.
- DriTac 7700 & 7800 Can be applied over old asphalt cutback adhesive residue as long as the adhesive ridges and raised residue have been completely removed from the subfloor with only minor stains remaining.
- WF Taylor Ironwood – Well-bonded residue from cutback adhesives.Primers
- WF Taylor Zephyr – Encapsulates cutback residue.
Mapei has several recommendations to aid in the re-installation of floor covering over a concrete substrate that has had a chemical mastic remover/stripper applied to it.
1. The contaminated slab should be mechanically abraded (shot blast or diamond grind) to attempt removal of any remaining contaminants. Typically, this may be achieved by ensuring that at least 1/8” thickness of the top layer of the concrete is completely removed.
2. Please note though, at this point the only way to try to determine if any residual chemical stripper may still be present is to do a core drill(s) and test for the presence of the contaminant. This test is NOT an absolute determiner if all residual chemical adhesive remover/stripper has been removed but can give insight and may help determine the next action steps. Any damage caused by residual contamination at this point is still not warrantable. To be fully warrantable all substrates must be structurally sound, dry, solid, and stable. They should be clean and free of dust, dirt, oil, grease, paint, curing agents, concrete sealers, epoxy adhesives, urethane adhesives, and any substance that may prevent, reduce, or affect adhesion or performance. This would include any residual adhesive stripper/remover.
3. If the chemical stripper is determined to still be present or if that is unknown, then the recommendation is to apply an epoxy primer/moisture barriers such as MAPEI Planiseal VS or Planiprep ET which will encapsulate potential residual stripper/adhesive remover and provide 100% RH and 14pH protection for the subsequent floor covering installation.
4. As an alternative method for installing over chemically treated concrete, MAPEI offers a two-step system to clean and encapsulate chemically treated concrete. MAPEI’s Planiprep Dust-Free Subfloor Preparation Solutions.
a. Remove any remaining adhesive residue with Planiprep AR adhesive remover. If the floor has no residual adhesive, then this step can be skipped.
b. Scour the surface with Planiprep SA concrete scouring agent to remove Planiprep AR residues and etch the concrete surface.
c. Cap the concrete subfloor with Planiprep ET epoxy concrete subfloor treatment to lock out any remaining Planiprep AR or Planiprep SA, and to control subfloor moisture up to 99%RH.
As a summary of options:
Best – Mechanically abrade (shot blast or diamond grind) and apply MAPEI Planiseal VS epoxy, prime with MAPEI Primer T, skimcoat with MAPEI Planiprep SC skimcoat patch and reinstall flooring. This is a fully warrantable option.
Better – MAPEI’s Planiprep Dust-Free Subfloor Preparation. Follow by priming, skimcoat and reinstall flooring. This is a fully warrantable option.
Good – Mechanically abrade (shot blast or diamond grind), skimcoat and reinstall flooring. It is important to note that this option cannot fully guarantee that subsequent damage from any remaining residual chemical stripper will not still occur. This option should have the full acknowledgment from all concerned parties (owner, architect, and GC).