Laying an engineered wood floor on underfloor heating

[Leftie]

I am getting conflicting advice from suppliers and installers about installing an engineered wood floor (18mm, with a 4mm hardwood top layer) over a concrete floor with underfloor heating.

The manufacturer video shows the installer simply glueing the tongues and groves over a vapour proof, low tog underlay to create a floating floor. One of the installers is suggesting laying the floor on a trowelled adhesive as he suggests that if it isn't entirely glued down the floor may bow/cup up if there is any movement at all.

I am obviously leaving the right expansion gaps but wondered if the installers were right to think about a complete glue job. I think I am using an old fashioned joiner to lay the floor for whom the idea of trowelling adhesive to stick the wood down appears strange. He did a solid wood floor a few years ago for me and there was certainly no trowelling in that!

 

[WoodYouLike]

The main benefit of fully bonding a wood-engineered floor on to a concrete floor which has a underfloor heating system embedded in it, is to avoid any air gaps between concrete and wood floor.
Air gaps can influence the effectiveness of your UFH in a negative way.

When fully bonding the floor, your fitter needs to use flexible adhesive and the correct notched trowel.

Most manufacturers of wood-engineered flooring will recommend the fully bond method to warrant their product guarantee.

 

[Leftie]

That is useful, is there an adhesive you recommend and the 'special' trowell??

 

[Leftie]

That is useful, is there an adhesive you recommend and the 'special' trowell??

Also, does it still need an underlay and if so, what type? I think that last time we used an underlay with a peel-off backing to stick the wood to the underlay as we went along and didn't use an adhesive at all.

 

[WoodYouLike]

You're confusing two different installation methods: fully bonding with flexible adhesive and fully bonding on self-adhesive underlayment.

Flexible adhesive does not need an underlayment, just a level, dry, cold concrete floor and notched trowel

You can't use just any self-adhesive underlayment when there's UFH involved: Elastilon Lock is specially made for this

 

[Leftie]

You're confusing two different installation methods: fully bonding with flexible adhesive and fully bonding on self-adhesive underlayment.

Flexible adhesive does not need an underlayment, just a level, dry, cold concrete floor and notched trowel

You can't use just any self-adhesive underlayment when there's UFH involved: Elastilon Lock is specially made for this

Does the underlay have to be double sided? I kiow it needs to be low Top and moisture resistant.

 

[WoodYouLike]

The Elastilon Lock is double sided for a specific reason - to give you the best result on UFH.
Otherwise, use flexible adhesive.