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Unit: Subfloor coatings and toppings

LMFFL2102A: Prepare, select and apply smoothing and patching compounds
LMFFL2103A: Select and apply appropriate compounds and additives
LMFFL2105A: Select, prepare and apply moisture barriers and damp proof membranes to concrete sub-floors

Section 1: Preparations

Preparing timber substrates


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Timber surfaces include plywood and particleboard sheeting and solid tongue-and-groove boards.

Solvents and strippers don't work well on timber floors, so you'll need to remove contaminants by sanding down to bare wood.

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Drum sanders are best on floors that need a lot of material removed.

Belt sanders provide a finer finish, but get clogged up more easily, so they are most effective when the surface only needs to be lightly sanded.

Orbital 'edgers' are used around skirting boards and corners.

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Once the sanding is completed, vacuum up all dust with an industrial vacuum cleaner.

Also check that all boards or sheets are well fixed and there are no squeaks or movement underfoot.

Re-nail or screw any loose boards or panels.

Cement-based toppings should not be used on a particleboard substrate unless the manufacturer recommends it.

This is because the particleboard is less tolerant of the high levels of moisture in the fresh underlayment than plywood or solid hardwood flooring.

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Where cement-based toppings are used on wooden subfloors, a diamond metal mesh should be put down first.

Installers often use 12 mm 'tilers lath', which provides a strong support structure for the underlayment to bond to.

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Learning activity

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The link below will take you to a YouTube tutorial produced by 'Allaboutflooring' on how to prepare and sand a timber subfloor. Have a look at this clip now.

Hardwood flooring subfloor preparation

Have you been involved in sanding a timber subfloor?

Did you do anything differently from the way it's shown in this clip?

If so, describe the differences.

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