Can You Pour Self-Levelling Compound Over Timber?

Yes, you can pour self-levelling compound over a timber subfloor, provided the timber is rigid, dry and securely fixed, and it is primed with a primer made for timber. Plywood, particleboard and Yellow Tongue flooring are all suitable when they meet those conditions. A timber floor that flexes, moves or is damp is not.

This guide explains how to check the subfloor, how to prime it, and how to pour LEVELMAX ProFlow over it.

Which timber subfloors are suitable?

Primer and self-levelling compound cannot compensate for a substrate that flexes or moves. If the floor bounces underfoot or sheets move at the joints, fix the structure before levelling.

Step 1: Check and prepare the subfloor

• Make sure it is rigid. Walk the floor and check that sheets do not move or deflect. Secure any loose sheets.
• Make sure it is dry. Timber must be dry before priming. Do not wet the timber at any stage before or during priming.
• Clean it. Remove dust, grease, wax, old adhesive and any loose material, then vacuum thoroughly.
• Seal gaps. Fill small holes, gaps between sheets and openings at walls with expanding foam or sand so the compound cannot leak through. Leaks are a common cause of a floor that looks flat when poured but dries with dips.

Step 2: Prime with a timber primer

Timber needs a thicker primer than concrete. Use LEVELMAX Primer X Timber, a ready-to-use grey acrylic made for timber substrates. Do not use Primer X Concentrate on timber.

1. Stir the primer thoroughly.
2. Apply it undiluted with a roller of at least 12 mm nap, and use a brush for edges and corners.
3. Work in two directions to a total wet film of at least 1.5 mm, with no bare timber showing.
4. If the timber absorbs the first coat quickly, apply a second coat once the first is dry.
5. Let it dry for 3–4 hours until it is completely dry. Keep the area free of dust and foot traffic, and vacuum and touch up any contaminated areas.

Do not pour onto primer that is still wet, tacky or patchy. For more detail, see Self-Levelling Compound Primer: Do You Need It?

Step 3: Mix and pour

1. Add one 20 kg bag of ProFlow to 4.8 L of clean, cool water.
2. Mix with a drill mixer at around 300 rpm for at least 3 minutes, rest for 2 minutes, then remix briefly.
3. Pour and spread within the 20–30 minute working time.
4. Keep doors and windows closed and the floor out of direct sun for 24 hours after pouring.

Do not mix by hand or in a concrete mixer, and never add extra water.

How thick can it go over timber?

ProFlow can be applied from 1 mm to 40 mm in a single coat. For greater depths, apply it in layers: let each layer set and dry, then prime it again before pouring the next.

When can you lay the floor covering?

Under normal conditions (23 °C and 50% relative humidity), ProFlow takes light foot traffic after about 3 hours and floor coverings from 24 hours. Thicker pours, low temperatures and high humidity extend these times. Over prepared timber, ProFlow can take tiles, vinyl, timber flooring or carpet.

Common mistakes on timber subfloors

• Pouring over a floor that flexes or has loose sheets
• Using a concrete primer instead of a timber primer
• Wetting the timber before priming
• Pouring before the primer is completely dry
• Leaving gaps between sheets unsealed, so the compound leaks through

Related reading

• Self-Levelling Compound: An Australian Guide
• Self-Levelling Compound Primer: Do You Need It?
• How Many Bags of Self-Levelling Compound Do You Need?

Primer X Timber (20 kg) and ProFlow (20 kg) are stocked at our Greenacre warehouse in Sydney. Call 1300 601 898 or request a trade quote.