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The Real Difference Between Engineered & Multi-Layered Wood Flooring

Multi-layered floors, multi floors, or semi solid floors as they are sometimes known, have become incredibly popular over the past 5 years, mainly because of the ease of manufacture and lower production cost. However, although most wood floor companies simply call them ‘engineered’, a multi floor is not an engineered floor. It’s not that they are trying to deceive you, it’s just that the word ‘engineered’ has almost become generic. But be warned, there is a huge difference between the two.
diagram of a ‘true’ engineered floor showing the constructionphotograph of a typical multi-layered floor panel cross-section

The two pictures above show (on the left) a cross section diagram of a ‘true’ engineered floor, and (on the right) a photograph of a typical multi-layered floor panel also in cross-section. They may look similar, but they are not.

A multi floor is made of plywood, usually birch, with a top layer of oak (or in fact any wood species) glued on top. For most environments, it is fairly stable and will perform quite well with minimal movement.
Moisture content, and why it matters to you

The moisture content of the top layer is usually between 9% – 11%, and although this may not mean much to you, it is vital to the fitter installing your floor. However, the problem arises the moment you introduce a multi-floor to underfloor heating. Most companies will tell you they are suitable, with some even offering some kind of guarantee. However, the guarantees are usually quite worthless as the criteria that needs to be met will prove to be impossible to maintain.

So here are the facts: multi floors are not suitable for use with underfloor heating unless they are EPH certified. Although many companies will sell multi floors for use with under floor heating and tell you they are guaranteed, the site conditions you will need to comply with will make the guarantee almost worthless.

Here’s why. The plywood used on these floors is incredibly stable and will not move at all. However, the top layer (with its 9% or so moisture content) will want to shrink the moment the underfloor heating is switched on, and this will cause ‘gapping’ or even surface splitting in the floor.

Engineered floors are much more complicated to manufacture, but the top layer of the wood species usually has a lower moisture content of between 6%-8%. It is a combination of this and the different construction technique that makes them more suitable.

Are engineered floors guaranteed for use with underfloor heating? Yes, but again with conditions attached.
So, is there a guaranteed product for use with underfloor heating?

Is there a product that you use that will make your floor ‘bomb proof’ against underfloor heating? The only products we are aware of that are fully certified against movement over underfloor heating with no conditions, are EPH certified floors.

We’ve more information on both semi-solid and engineered floors in our FAQ section, and also a page on underfloor heating in our ‘Guide’ section.