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Competencies covered

MSFFL2006: Prepare, select and apply smoothing and patching compounds

MSFFL2007: Select and apply appropriate compounds and additives

MSFFL2009: Select, prepare and apply moisture barriers and damp proof membranes to concrete sub-floors

Applying moisture suppressants


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Moisture suppressants are mostly used to 'fast track' a floor covering installation when the concrete is still green and has not yet reached an acceptable RH level.

They're not designed to provide the same level of protection as a full moisture barrier.

Most moisture suppressants are water-based products that can be applied with a roller, brush or sprayer.

When a sprayer is used, several passes are applied until the area is evenly saturated. Then the excess material in the low spots is spread with a broom to the high spots.

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As the concrete pores fill up, any contaminants trapped inside the pores will tend to float to the surface. So the concrete needs to be sanded and vacuumed 24 hours after the suppressant is applied to remove the residual chemicals and substances.

As with moisture barriers, you must carry expansion joints through to the finished floor height. These are typically filled with a jointing system made from polyurethane, silicone or epoxy resin.

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Learning activity

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Do your own research on moisture suppressants and see if you can find a product that provides this level of moisture treatment.

Name the product and the manufacturer.

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