Description
Roberts FlexiFlo — branded FLEXI on the datasheet — is a fibre-reinforced, flexible self-levelling compound built specifically with timber flooring installation in mind, alongside general use over concrete and particle board substrates. Its enhanced flexibility is the point of difference from a standard rigid self-leveller: timber flooring moves with humidity and temperature more than tile or resilient flooring, so the levelling layer underneath benefits from some give rather than being completely rigid.
When levelling ahead of timber flooring over a concrete substrate specifically, the minimum coat thickness is 3mm — thinner applications aren’t rated to give timber flooring the stable, flexible base it needs. For internal use only, it also handles wheelchair traffic and underfloor heating once cured, broadening where it can be specified beyond just timber-flooring prep work.
Technical Specifications
| Thickness range | 1-20mm (minimum 3mm under timber over concrete) |
|---|---|
| Mixing ratio | 20kg bag with 4.6-4.8L clean water |
| Mixing method | Forced-action, high-shear stirrer at approx. 600 rpm |
| Accepts most floor coverings | Approx. 12 hours |
| Timber flooring installation | 24 hours after application |
| Coverage | Approx. 4m² per 20kg bag @ 3mm thickness |
| Substrates | Concrete, timber, particle board |
| Packaging | 20kg bags |
Where to Use
- Preparing concrete or particle board substrates for timber flooring
- New or existing internal concrete and timber substrates generally
- Areas requiring good load resistance, including wheelchair traffic
- Underfloor heating systems — internal use only
How to Apply
- Prepare the substrate — must be structurally sound, smooth, stable, dry and clean, with rough surfaces and voids evened or filled first.
- Check readings — carry out relative humidity and pH testing on concrete per AS 1884-2021, using RLA Moisture Seal where required.
- Mix — add Roberts FLEXI gradually into pre-measured water, mixing for a further 3 minutes to a smooth, homogenous consistency.
- Apply — spread to the required thickness (minimum 3mm under timber over concrete) by trowel or pump.
- Allow to cure — ready for most floor coverings after approximately 12 hours; timber flooring installation after 24 hours.
Important Notes
- Do not mix by hand and do not add excess water.
- Concrete substrates must be at least 14 days old before application.
- Minimum subfloor temperature before installation is 10°C; contact RLA Technical for guidance outside 5-35°C.
- Internal use only.
Timber flooring puts different demands on a levelling layer than tile or vinyl does — it moves with seasonal humidity changes far more than a rigid floor covering, so a completely inflexible levelling compound underneath can become a stress point rather than a stable base over years of use. FlexiFlo’s fibre reinforcement and enhanced flexibility are specifically there to move with that seasonal cycling rather than crack or delaminate, which is the real distinction between a general-purpose self-leveller and one purpose-built to sit under timber.
