Self Levelling Compound on Floorboards
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Can you use Self-Levelling Compound on Floorboards?

You can’t usually apply self-levelling compound directly onto timber floorboards due to Gaps, Steps and Movement between the individual floorboards. Domestic Floor Layers usually insist that the floor is overboard with a minimum of 6mm thick plywood, before applying any self-levelling compound.

Note: The floorboards must still be firmly affixed to the floor joists before the floor is over-boarded in Plywood. This can be done by screwing the floorboards down with wood screws. The basic principles behind over boarding floorboards can be found in our other article “How to Ply over Floorboards“.

My Floorboards
My Tongue and Groove Floorboards

You can usually apply self-levelling compound onto Chipboard floorboards or Chipboard flooring sheets, as they usually interlock together tightly removing any gaps or steps. Can you use self-levelling compound over chipboard?

Chipboard flooring sheets
Chipboard floorboards (Chipboard Flooring Sheets)

Providing they are screwed down adequately they will make a suitable sub-floor for the self-levelling compound. Just make sure to seal any gaps around the perimeter of the room with silicone or expanding foam.

The only way you could self-level directly on traditional timber floorboards would be if they are all tongue and grooved together tightly (preferably glued), so there is nowhere for the self-levelling compound to escape. There must be no steps between individual floorboards and the whole floor must be securely fixed to the joists with no movement. I am yet to see this in reality.

Gaps

Gaps between the individual boards can allow the self-levelling compound to seep out. This can create a big problem if self-levelling compound starts pouring out of your ceiling.

Gappy Floor Boards
Gappy Floor Boards

Over-boarding with large Plywood sheets helps to reduce the number of joints over the floor, therefore reducing the number of places the self-levelling compound can escape from.

Steps

Quite often you can have steps usually up to about 2mm between floorboards where they meet together, end to end. This can cause a problem if some of the more pronounced floorboards stick out through the finished pour of self-levelling compound.

Over-boarding the floor with Plywood helps to smooth out any small steps between floorboards, leaving a smooth, seamless floor covering with fewer joins.

Movement

Individual timber floorboards are also likely to move slightly when walked on. This can cause the self-levelling compound to crack. The plywood over-boarding helps to unify the floor. Because the plywood is screwed to all the individual floorboards It will move as one. Rather than a large number of independent floorboards.

Screwing Down Floorboards
Screwing Down Floorboards

When screwing timber floorboards down with wood screws, you should try to position them next to the old fixings. This ensures that you are screwing into a floor joist, it also reduces the likelihood of screwing through a pipe. This is particularly important if you are working on a bathroom floor.

Can you use self-levelling compound on chipboard floorboards?

If the chipboard flooring does contain lots of gaps, steps and cut-outs where pipe runs have been, it may still be best to over-Ply the floor. We have provided the fundamentals of over-boarding your floor with plywood in our other artical How to Ply over Floorboards

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