Concrete second floor

[vertical fool]

My second flor flat has a concrete floor which is covered with a asphalt or a bitumen. Do I have to lay a damp proof course if its on the second?

 

[Static]

No, unless you live underground.

 

[vertical fool]

Ok, so I don`t need to use a damp proof membrane.

What will the stuff on floor be it looks like some sort of asphalt/bitumen?
Are there products like this that I can buy?
Would they be any better than self levelling compound?

I`ve bouught the niva boards from Ikea for using as an underlay, however they seem very firm/dense. Will these absorb slight differences in the level?

I`ve also got the foam underlay from B&Q that acts as a DPM as well. if I don`t need the DPM should I return this and get the thicker fibreboaads? Or use both the ikea boards and B&Q foam underlay ( all in one, grey stuff)?

 

[Static]

What will the stuff on floor be it looks like some sort of asphalt/bitumen?

Yep probably is.
Hmm sounds like you are putting something on the floor.. wooden flooring maybe and not replacing the floor itself.. in which case i'll let WYL answer

 

[vertical fool]

Yeah, I`m laying engineered wood flooring, sorry I forgot to say. I did put it in an earlier post but got no replies although I didn`t make my questions very clear. Thanks for your replies though Static.

 

[WoodYouLike]

.. in which case i'll let WYL answer

Vertical fool: you're thicker underlay can handle minor differences in the concrete. You can install them right on the bitumen/asphalt if you want.

Hope this helps

 

[vertical fool]

The niva boards are 4mm thick although very dense so I didn`t think they would compensate for much uneveness.

How much difference do you think they will compensate for?

Should I use both of the underlays?

Thanks

 

[WoodYouLike]

They can compensate little bumps. if you don't trust them to so the work go for a bit thicker underlayment boards. would help if you could tell us what uneveness you've got.
You don't need DPM on concete floors on the second floor (if the concrete is 'old' not new).

 

[vertical fool]

The uneveness I`ve got is upto around 6mm around the doorway. Around where the fireplace has been has been fiiled with a black bitumen or ashphaly. In the bay window which has been squared of since being refurbed has a dip which is heading toward 10 mm especially in the corners which have been filled with the ashpalt stuff.

The concrete is old but if I have to use a self levelling compound then this would obviously be new, would this require a DPM.

Thanks

 

[WoodYouLike]

You're best options is indeed to level out. Depending on the leveling compound you use leave the new screed to dry out naturally as long as indicated on the instructions (and then some). If there are only patches of new screed a DPM is not really needed, but wouldn't do any harm also.

 

[vertical fool]

Thanks WUL

What be the greatest surface deviation you would work on without using a levelling compound?

What underlay would you use?

Is there any self levelling compounds or similar products that are the easiest to use? Such as being able to add lots of water so that they can pretty much level themselves.

I`m worried about my ability to fill the deviations and to feather it out properly without making a pigs ear of it.

Thanks

 

[WoodYouLike]

Thanks WUL

What be the greatest surface deviation you would work on without using a levelling compound?

2 - 3 mm over 1 meter
Then we use a simple underlayment (2 - 3mm thick) and where needed 'level' with extra bits of this underlayment.

For leveling compound I hand you back to Static, we stay away from anything containing screed/concrete cause it can have a terrible effect on the wood (concrete dust I mean, can/will mark unfinished wood, especially Oak)

 

[Static]

Also screed and leveling compounds can take weeks to dry. Your better off trying the simplest solution first (especially one that is easy to remove and try a different solution if its not what you wanted)

 

[vertical fool]

and where needed 'level' with extra bits of this underlayment.

How do you know where to add the extra underlay? Through knowing where the dips are or from when laying the wood and being able to see the difference?

When you say the concrete dust can mark the wood. Is this usually OK if the area is kept reasonably clean?

Thanks for your replies, I`m more confident in respect to levelling but more worried about the concrete dust marking the wood.

Thanks

Vertical

 

[WoodYouLike]

Sorry, didn't mean to worry you about the dust
What I meant was we don't stock, carry, deliver anything to do with concrete to avoid 'spilling' of the dry matter onto unfinished wood.
Stock the wood in another area when you use leveling compound. Once it has dried, no problems.
Extra underlayment: trial and error; check and double check the 'movement' of the installed boards when you have to use extra underlayment and correct where needed (remove or add)