Trowel Notch Selection for Resilient Adhesives

The adhesive label decides the notch, not habit, and the substrate decides which line of the label you use. Porous substrates (concrete, plywood) often take a larger notch than non-porous ones (old vinyl, sealed concrete, patch), because porous surfaces absorb some of the adhesive. Too much adhesive bleeds through seams and telegraphs trowel ridges; too little leaves hollow spots and failed bonds. Read the label, match the substrate, replace the trowel when it wears, and check coverage by lifting a piece after you set it.

Reading a notch size

Notch numbers tell you how much adhesive the trowel lays down.

Notch sizes are written width x depth x spacing. A 1/16" x 1/32" x 1/32" U-notch has notches 1/16" wide and 1/32" deep, spaced 1/32" apart. Never swap notch shapes, even when the numbers match: square, U and V notches lay down different amounts of adhesive.

Step by step

Follow these steps on every job to put the right amount of adhesive down.

1. Confirm the substrate is porous or non-porous. A drop of water that soaks in within a minute or so means porous.
2. Pick the notch from the adhesive label for that flooring and substrate.
3. Spread holding the trowel at a consistent angle so the notches reach the floor.
4. Follow the open time on the label. Setting flooring into wet or overdry adhesive can cause bond failure.
5. Lay the flooring and roll it as the flooring maker requires. See Rolling resilient floors for roller weight and technique.
6. Pull up a piece in the first area and look at the back. You want even transfer without puddles.

Common mistakes

Adhesive problems usually trace back to the trowel, the timing or skipping the roller.

• Worn notches. A trowel wears on concrete and spreads less and less. Replace or re-notch it regularly.
• Using a tile trowel for resilient adhesive. It puts down far too much, and the excess bleeds through.
• Ignoring open time. Many resilient adhesives need to flash before you set the flooring.
• Not rolling. Roll in both directions with a 100 lb roller to flatten trowel ridges.^[1]

Tools we carry

The right notch only works with a trowel that is true, so keep spares and replacement blades on hand for the wear points above.

• Crain No. 431 1/16" V-Notch Trowel
• Gundlach Versablade replaceable blades and handles
• Shop all trowels and adhesives.

References

1. AHF Contract: Commercial heterogeneous sheet vinyl installation instructions

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