What to put under Real Timber Flooring?

[DIYWell]

Suspended ground floor; joists with floor panels on top, a little flexible screed on top to level off a duff area. Now the plan is to put 18mm real oak flooring on top.

I've read in some web sites that a that some sort of damp proof covering sould go down e.g. builders' paper, and on other sites, just put the new floor straight down.

What do folk here advise?

 

[WoodYouLike]

It manly depends on the sizes of your 18mm solid Oak floor if you can install it floating or if you have to fully bond it to the concrete with flexible adhesive.

 

[DIYWell]

It's a suspended wooden floor, no concrete.

Plan is for it to fixed down with secret nails.

 

[HMCFlooring]

What are the floor panels? Ply or chipboard?

 

[DIYWell]

What are the floor panels? Ply or chipboard?

Chipboard

 

[HMCFlooring]

Nailing into chipboard is not the best option at all. Chipboard does not hold a nail very well, it may seem good at first but the nail will get looser with the natural expansion and contraction of the hardwood floor.

A trowel out flexible wood flooring adhesive would be the best option for fitting your floor.

 

[WoodYouLike]

Nailing into chipboard is not the best option at all. Chipboard does not hold a nail very well, it may seem good at first but the nail will get looser with the natural expansion and contraction of the hardwood floor.

A trowel out flexible wood flooring adhesive would be the best option for fitting your floor.

Agree with the nailing on chipboard, but don't agree with glueing it down. Most chipboard has a moist repellent surface nowadays, which does not agree with any of the modern adhesives.

Best bet would be to opt for Elastilon self-adhesive underlayment if the boards are narrow and many short lengths.

 

[HMCFlooring]

Never encountered this and i have for various reasons had to lift floors/single boards that i have glued down with a flexible PU over waterproofed flooring chipboard. The lifted boards always pull the top surface of the chip board much in the same way as with a ply.

Never fancied the Elastilon (just a floating floor at the end of the day) always wondered how damaged boards in the floor are replaced?

 

[DIYWell]

That's an interesting option.

There's a thin layer of flexible screed on top of the chipboard which the builder put down to fix a problem with the floor. Would you still recommend the Elasilon approach?

 

[WoodYouLike]

Glueing straight over a thin screed layer over chipboard? I wouldn't.

 

[DIYWell]

Glueing straight over a thin screed layer over chipboard? I wouldn't.

What's your reasoning for a change of heart?

The glue is between the underlay and the timber. The underlay sits unbonded on the surface. Can you tell me what is the difference between the underlay sitting on chipboard versus sitting on the screed that's bonded to the chipboard please?

 

[crazydaze]

Chipboard is significantly weaker than the bond of glue and screed, the chipboard WILL blow.

 

[HMCFlooring]

sorry missed the screed over an area probably not the best bond to be fair starting to favour the floating floor.

Crazydave
Yeah it is a weaker bond but then so is nailing into ply. There is nothing worse than lifting a floor glued to screed/concrete (always pull clumps of concrete up), lifting nail down boards on ply is a piece of ****.

Woodyoulike
Elastilon is not glued to the sub floor, it forms a bond with the flooring, now when the wood flooring wants to expand (summer) the elastilon is under tension (it wants to pull the wood back). Its not attached to the sub floor the wood wants to expand the elastilon wants to pull it back, surely this has to pull the floor out of shape (lifted in the middle)?
This is just interesting to me and would like to hear you thoughts.

 

[DIYWell]

Ok, I'm confused now and perhaps I've misunderstood something here.

WoodYouLike - Are you happy that the Elastilon on top of a screeded floor is a workable solution?

 

[HMCFlooring]

Its a workable solution yes. much better than nailing it down.