Floating a Solid Oak Floor with No Glue

Discussion in 'Carpenters' Talk' started by Marcus Dare, Nov 13, 2020.

  1. Marcus Dare

    Marcus Dare Member

    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 is this just a TERRIBLE idea?

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

    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,

    Last edited: Nov 13, 2020
  2. Jord86

    Jord86 Screwfix Select

    I wouldn't do it personally. If you're using 18mm oak then it will have cost you a pretty penny so you want to get it right. Either go with the flooring company's recommendation as they do it day in and out, or bond the oak to the floor using Sika T54 adhesive which will take up the slight deviance and allow the oak to expand and contract over the seasons without issue. Do not glue the tongues or grooves, oak needs to be able to move.
    Marcus Dare likes this.
  3. Marcus Dare

    Marcus Dare Member

    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 make my own version of an adhesive underlay.

    This is from the flooring manufacturers website:

  4. Red Star Boats

    Red Star Boats Active Member

    You may want to experiment first, I think you may find it difficult to get anything to adhere reliably to the fibre boards. It’s your floor but at 50m2 you’ve got to be in at least a couple of grand why risk it. The self adhesive underlay is unbelievably sticky and tough, kind of like bitumen covered cloth, it holds the floor together so that it acts and behaves a single entity. I believe if you follow your idea the floor boards will continue to move independently, breaking their bond with the fibreboard underlay and look a mess in short order. Do the job properly, if there was any advantage to your method and it worked flooring professionals would be using it.
    Marcus Dare likes this.
  5. Marcus Dare

    Marcus Dare Member


    I will return our 5mm green fibre board and buy rolls of 3mm AcuStick self adhesive and acoustic underlay, which is on several flooring websites.

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