Plywood over floorboards?

If your floorboards are gappy and uneven then it is often best practice to overboard them with Plywood. This helps you to create a smooth unified surface without having to rip up all your old floorboards. Once the floor has been over-boarded with Plywood, you can confidently apply your finished floor covering or self-levelling compound.

If you have a timber floor with wooden tongue and grove floorboards like the one pictured on the left, it would be wise to Ply over the floorboards, before applying a self-levelling compound or floor covering.

Over-Plying the floor before applying a self-levelling compound solves two major problems. One is Leakage between the floorboards and the other is Movement in the subfloor. This is especially important when working on a suspended timber 1st floor, like the one pictured below. Or on an upstairs bathroom for example.

Over-boarding the floor in Plywood drastically reduces the total number of joints in the floor covering. This dramatically reduces the chances of any leakage between the floorboards.

Plywood sheets come in a standard size of 1220mm x 2440mmm, so for a small bathroom, you might only need two or three sheets. You may only have two or three joins instead of 20 or more with traditional timber floorboards.

6mm thick Plywood is often the best to use, as it will not greatly raise the floor level. It is still thick enough to bridge any small gaps and steps between floorboards or flooring sheets.

If the chipboard flooring sheets have been fitted neatly with no gaps or steps between the sheets. There will be no need to over-ply it, before applying the self-levelling compound. Just make sure to use a latex-mixed self-levelling compound. If you use a self-levelling compound that is mixed with water, the chipboard will absorb the moisture and start to expand.

If you want to find out the basics of How to Ply over Floorboards you can read our other article.