Floating a Solid Oak Floor with No Glue

19 Nov 2016
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United Kingdom
Hi there,

We have already bought our 18mm thick tongue and groove Solid Oak Flooring, that is pre oiled. It's also very heavy and weighs approx 700kg across 50 sq metres.

It is currently being acclimatised for 7 days.

The concrete sub floor has has been self levelled and is mostly very level, expect for minor 1-2mm variations around 2 join areas. The sub floor has also been treated with 2 coats of Sika liquid DPM and there should no moisture coming through at all.

I have already bought 5mm thick Fibre Board underlay, that has good insulation and sound reduction properties and levelling properties to compensate for those minor floor variations.

The manufacturers website and other websites also state that this fibre board CAN be used with Solid Wood Flooring.

So what i want to do is to apply the 5mm fibre board underlay and "Float" the solid oak floor with no glueing and with 12.5mm expansion gaps on all 4 sides. These gaps will also be filled with 12.5mm cork strips. The fibre board is also fairly course and the undersides of the oak flooring are grooved and will dig into the fibre board slightly when you stand on the oak floor.

OR could i float the floor, but Glue all of the tongue and groove sections?

OR is this just a TERRIBLE idea?

The flooring company mention using a Self Adhesive Underlay that sticks to the wood but floats on the sub floor. But this isn't as thick or as insulative as the fibre board or as good for levelling imperfections.

One other idea of mine is to use the 5mm Fibre Board and another seperate adhesive to stick the oak flooring to the fibre board. Providing a similar result to the self adhesive underlay recommended by the flooring company.

Any advice would be greatly appreciated,

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You can’t float solid wood. If you do it will move a lot over the season and it will gap and creak.
Thanks for your reply.

I think I will go for a semi-float option, which is mentioned by the manufacturer of my flooring and by several other solid wood specialists.

They recommend a 3mm self adhesive underlay that floats on the sub floor, but sticks strongly to the oak boards.

I will use my 5mm wood fibre board floated on the sub floor and i will stick my oak boards to the fibre board using a strong and flexible wood glue.

Which isn’t exactly the same, but it’s fairly close. I will most make my own version of an adhesive underlay.

This is from the flooring manufacturers website:

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Fibre board is very weak and the wood will sheer off that in no time.

I've used the insterlay system before as one of my customers bought it at B&Q with some cheap wood. It went down ok to be fair and felt solid but I would still rather glue the wood to the screed.
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We will return the 5mm green fibreboard and buy rolls of 3mm AcuStick self adhesive and acoustic underlay that is sold on several solid wood flooring websites.
You can’t float solid wood. If you do it will move a lot over the season and it will gap and creak.

I have c60 sqm of 18mm oak in my house, all floated on weyroc, which itself is floated on insulation. I've had remarkably few problems, mainly due to minor leaks. The first bit: hall, kitchen, utility and back hall and wc is 15 years old. That wasn't glued in the t&g. I recently sanded and resurfaced it. The other 2 areas, tv room and lounge dining room have been 9 and 2 years respectively, and both are glued in the grooves. They are in near-perfect condition.

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