Hi everyone new screed advise needed

[rob1]

great forum people almost to much information to read!

Anyway i would very much appreciate some advise, i am in the process of building myself an extension, I have just laid 7/9/12 a 75mm deep C25 concrete & fibre screed over wet underfloor heating pipes., i have not as yet sealed the floor.


my screeding has created a few bumps in the floor so in order to get this as flat as possible i have purchased some Tarmac flexible floor leveller (with latex), my problem is that information suggests that i should let the screed dry for 75 days this is not really an option ! i am thinking of leaving it two weeks weeks.


1. Do i need to seal the floor before i apply the Tarmac floor levelling compound as i am worried about moisture, being trapped between the screed & the levelling compound
2. I have purchased 600mm X 600mm 10mm porcelain tiles to lay on the floor what would you recommend as a tile adhesive as the levelling compound has latex properties in it?
the floor area is only 28 sq. meters


many thanks

 

[DHTiling]

You cannot rush a new screed like that.

Oh and welcome..

 

[rob1]

Will happily leave screed longer if needed, more worried about the tiles fixing really?

 

[White Room]

There's alot of moisture in your floor and needs time to cure.....Hi and welcome.

 

[Ajax123]

Is it a concrete with coarse and fine aggregate and cement or is it a screed with just sand and cement?

 

[rob1]

Ajax its a bit of a combi-mix really, looks like sharp sand & cement, some of the grains of sand/gravel are 5mm in diameter which is what i would expect & includes fibres . I asked a site agent whilst on-site today his thoughts , he said he has not sealed a new screed floor in the last ten years & told me not to worry & just place the levelling compound down after a week or two. or don't bother & just put the tiles down., not that i don't trust his advice he has 40+ years experience but a second opinion is what i need, i am a sparky by trade so do ask & watch contractors when they are on builds i am on if i require information , but i am not on a build doing a floor at the moment, most of the information i have read is vague at best with regards to screeds most people quote (1day per mm)drying time which on modern builds is totally out the window. the last job i was on was a (new swimming pool) which had underfloor heating & 150mm screed laid across two floors & 4000 sq meters but i was not paying to much attention to it at the time and have as yet to see the finished facility.

 

[Ajax123]

On the basis that it is a sand cement screed presumably site mixed itis likely that it will be too wet for a few weeks yet to level directly. You have a couple of choices.
first choice would be to use a liquid damp proof membrane to suppress the residual moisture and a levelling compound on top of that. The second option would be to place an uncoupling membrane using a cement based adhesive and then either use a levelling compound on top of that or use a thick bed adhesive to take out the undulations. My preference would be option 1. There are loads of damp proof membranes available these days and they are not all that expensive.

 

[White Room]

On the basis that it is a sand cement screed presumably site mixed itis likely that it will be too wet for a few weeks yet to level directly. You have a couple of choices.
first choice would be to use a liquid damp proof membrane to suppress the residual moisture and a levelling compound on top of that. The second option would be to place an uncoupling membrane using a cement based adhesive and then either use a levelling compound on top of that or use a thick bed adhesive to take out the undulations. My preference would be option 1. There are loads of damp proof membranes available these days and they are not all that expensive.

What sort liquid membrane would that be Alan.....

 

[rob1]

Screed was mixed by an easymix concrete lorry & dropped on my driveway for me to barrow in & lay, thanks for the advice i everyone i will have a look at your suggestions Ajax and will let you know what i decide, & if anyone is remotely interested give & show the finished results.

 

[Ajax123]

What sort liquid membrane would that be Alan.....

2 part Epoxy generally. Eg bostik universal one coat, tremco ES membrane, Merlin barrier coat etc. ther are dozens. Hey tend to besed mre in the vinyl business but there s no reason why the should not be used with rigid coverings.