Wooden Floor height

[bathroomboy]

Need to over board usually use ply, but putting ufh then some latex slc and on top that of that Ditra, will I be better using a backer board instead of ply to keep the height down, will it be strong enough and whats reccomended.

[garythetiler]

all depends on the sub floor

[Dave]

What are you over boarding and how big is the floor..? And why are you using ditra..?..

[Sully]

And Ditra would normally sit under the UFH - covered in a 3mm bed of slc ensuring that the cables don't come in contact with the ditra.

[Dave]

Sully..Ditra can be installed both ways......but it performs better installed above the UFH....

quote from schluter..

Schlüter-DITRA is also recommended for uncoupling of radiant heated floors consisting of thin electric heating mats. Schlüter-DITRA may be installed either above or below the heating mat. However, the uncoupling function is more effective if Schlüter-DITRA is installed above the heating mat.

[bathroomboy]

It's t&g wooden floor which Idon't want to rip out due do it going under walls etc.

[Dave]

And why ditra...?

[Sully]

Sully..Ditra can be installed both ways......but it performs better installed above the UFH....

quote from schluter..

Good to know Dave - I've only used it to overcome issues with new screeds (fast track, whereby the screed hasn't had the full cure time) and in that case, it sits below the UFH - according to Schluter tech. It needs to be flooded with slc as the cables shouldn't come in contact with it. Out of interest, in what spec would you sit it above the UFH? I also assume the cables would need to be flooded with slc as again, the ditra shouldn't come in contact with them as far as I'm aware.

As for using it to overcome floorboard movement, if that's what you are planning Bathroomboy - that's not what it's designed to do. I personally would overboard with a tilebacker board / marmox insullation boards, fix mats, flood with SLC and tile (although some guys are happy to fix directly over ufh mats with adhesive - I can't see the benefit or justify the risks of damaging the cables).

[bathroomboy]

Thanks Sully how thick is the marmox board? and is it cemented down in any way or just screwed like ply 150m/m centres.

[Dave]

Out of interest, in what spec would you sit it above the UFH?

With piped( wet heat) or Electric UFH.....This allows the full functions of the uncoupling part of ditra...

[Sully]

With piped( wet heat) or Electric UFH.....This allows the full functions of the uncoupling part of ditra...

So we are not talking about new screed solutions here (as Schluter advise the opposite i.e ditra, slc and then mats) - are you referring to say old screeds which have settled with fractures?

[Sully]

Thanks Sully how thick is the marmox board? and is it cemented down in any way or just screwed like ply 150m/m centres.

I'd suggest 10mm (as the 6mm won't help with stabalising the floor). I'd fix it with a combo of addy and screwfixings - bolt and braces which reduce risks. I use aquapanel type washers to secure the marmox. Don't forget to secure the boards to the joists first.

[Dave]

So we are not talking about new screed solutions here (as Schluter advise the opposite i.e ditra, slc and then mats) - are you referring to say old screeds which have settled with fractures?

Obvioulsy on a new screed then you need Ditra to work in another way as well......"vapour equalisation" then YES!! you would put electric ufh on top....but wet heat is in the screed .....

Incidently whilst on the subject of ditra and new screeds....what adhesive do you use for sticking the Ditra down on new screeds..?..

This will help newcomers to ditra as well...

[doug boardley]

Bal Green?

[Dave]

YES doug......needs to be a slow setting highly flexible adhesive.....this will accomodate moisture from the new screed better than rapid setting ones....and cope with screed/concrete shrinkage...

[Sully]

Incidently whilst on the subject of ditra and new screeds....what adhesive do you use for sticking the Ditra down on new screeds..?..

This will help newcomers to ditra as well...[/quote]


Mapei Keraquick - and don't prime the new screed.

[Brad]

hi sully....

i don't understand your comment about not using ditra as a way to overcome lateral movement in a wooden floor.........from what i have read about the product that is one of the reasons for the manufacture and use of the product......please explain

[Brad]

hi dave

just wondering about your question as to why bathroomboy is using ditra on a wooden floor.....is it not advisable to use ditra as a remedy for any lateral movement that may occur?

[Dave]

hi dave

just wondering about your question as to why bathroomboy is using ditra on a wooden floor.....is it not advisable to use ditra as a remedy for any lateral movement that may occur?

I asked cause it is not always needed if using ceramics/porcelain tiles....i tend to just use it if using travertine etc etc....as they crack a lot easier than ceramics..

If a fixer thinks that he MIGHT have a lateral expansion issue with a floor, then yes use an uncoupling membrane..imo..

[Brad]

ok mate.....thanks