Advice please with levelling concrete floor for solid oak

[flyingsparks]

Hi I am about to be laying a solid oak floor through kitchen dining room and hallway. Where the dining room and kitchen are there use to be. Wall I between and there is a slight difference in floor level. I need to lay some self levelling compound but unsure on the best one to use for this job. I'm not sure if there is a Dpm under the floor but the house is a 1947council built house so do you think there probably is a Dpm? What's the best way to lay the oak floor over this? Lay another Dpm and glue with something? All help Ppreciated! Thanks Chris. [/img]

 

[crazydaze]

You can't lay the oak direct to the floor until you have either measured for moisture in the floor or gone the whole hog and treated the whole floor with a DPM.

If you are thinking of floating the floor, a moisture tolerant Screed maybe the minimum you can get away with, a proper moisture test of the floor with a hydrometer should really be used to test it, if you float with a sheet DPM you may get away with a 'gappy' finish through the seasons, like most things it's all in the prep. If you are fitting multiple areas through standard doorways it is important to fit suitable door profiles in these areas.

 

[coolevilangel]

at 1947 theres no way at all that you have an existing dpm, they only came into effect after the 1960's
Do NOT float a solid oak floor, it has to be fixed to the floor only
Either glued ot nailed etc, but def not floating
dpm dpm dpm, if in doubt dpm

 

[flyingsparks]

Coolevilangel, why do you say not to float the floor when it appears that this is quite a common way to fit solid oak flooring? Just curious to your reasoning! Ok no worries will make sure I dpm! Thanks.

 

[mattysupra]

floating solids is a big no.


Solids move around a lot more than a engineered. As a example- for ever 1%mc change the face of a solid will move 0.25%.

So if we had a 4% MC change the solid wood will now expand by 1% of its face size. Lets take a 100mm wide product. If we had a 4%mc change that 100mm wide product will expand by 1mm.

So we have -

100mm + 1% = 101mm.

If the room is say 4m wide and we have a 1% movement factor (4%mc change) that means we need 4cm expansion. (when floating)

So lets go back to floating. If we do have a 4%mc change in the wood flooring then we have worked out we need 4cm expansion. If the floor is moving as a mass then the pressures put on the tongues (maybe 6mm or so of timber) is put under great pressure. The tongues can fail. But more to the point is the mass of expansion. (when floating)

IF the flooring is glued down then the glue will have a lot more contact than just the tongue. It will also be holding onto the subfloor. This will restrain the wood a lot more and reduce its movement. (fully bonded)

so, how possible is it to get a 4%mc change?

well very . A simple shift from 40%rh to 65%rh will give you a 4%mc change in the wood flooring.

 

[coolevilangel]

Coolevilangel, why do you say not to float the floor when it appears that this is quite a common way to fit solid oak flooring? Just curious to your reasoning! Ok no worries will make sure I dpm! Thanks.

Its a common way to do it for the diy'ers out there
No professional would ever consider that way, due to the reasons mattysupra has kindly pointed out in detail

 

[popandu]

floating solids is a big no.


Solids move around a lot more than a engineered. As a example- for ever 1%mc change the face of a solid will move 0.25%.

So if we had a 4% MC change the solid wood will now expand by 1% of its face size. Lets take a 100mm wide product. If we had a 4%mc change that 100mm wide product will expand by 1mm.

So we have -

100mm + 1% = 101mm.

If the room is say 4m wide and we have a 1% movement factor (4%mc change) that means we need 4cm expansion. (when floating)

So lets go back to floating. If we do have a 4%mc change in the wood flooring then we have worked out we need 4cm expansion. If the floor is moving as a mass then the pressures put on the tongues (maybe 6mm or so of timber) is put under great pressure. The tongues can fail. But more to the point is the mass of expansion. (when floating)

IF the flooring is glued down then the glue will have a lot more contact than just the tongue. It will also be holding onto the subfloor. This will restrain the wood a lot more and reduce its movement. (fully bonded)

so, how possible is it to get a 4%mc change?

well very . A simple shift from 40%rh to 65%rh will give you a 4%mc change in the wood flooring.

Very nice explanation!