Mapei renovation screed primer

[EatingSnakes]

Hey guys

I've got a new, tampered concrete floor.

Not sure if I need primer before applying Mapei Renovation Screed

If yes, I've got a ton of SBR. Will this work?

The screed will be containing UFH pipes.

Thanks

ES

 

[Italy]

.............

 

[Qwerty]

As above, it's always best to follow manufacturers instructions and use the same primers. You could phone Mapei technical dept tomorrow and ask your question but I'm pretty sure they will stick to the primers listed above. They may possibly say that Primer G will suffice but to be honest your SBR will work and plenty here would use it with no issues. It does also depend if it is the correct type of SBR

 

[EatingSnakes]

Thanks guys

Yeah I had a good search of the forum and have seen plenty of people use SBR but just wanted to make sure as its my first time.

Its ever build brand Bonding SBR

 

[One Day]

I'd be happy using SBR. Diluted probably 3:1 as everbuild is quite diluted anyway.
Make sure you're not bonding dust though - vaccuum first.

 

[EatingSnakes]

Thanks mate.

So that's 3 parts SBR to 1 part water.

Thanks so much

 

[Wayne Brown]

What sort of underfloor heating going down? Electric or a wet system any insulation going down first

 

[EatingSnakes]

Wet.

got 100mm kingspan in place.

 

[Wayne Brown]

Like this ? 100mm celotex laid on the slab a polythene dpm laid on top the celotex and cut and taped expansion foam strip added all around the perimeter of the room and structures this one will have a flow screed pumped in to a 90mm thickness , please explain how your floor is being done em I missing something?

 

[EatingSnakes]

From bottom to top:
DPM
100mm Kingspan
DPM
100mm concrete
16mm pipe
28mm mapei renovation screed
Tiles

 

[Dumbo]

I dont know this as I am not familiar with mapei products but I think it's worth checking with mapei that 12mm over the pipes is sufficient ..

 

[WetSaw]

....and that the concrete is dry enough.

 

[Wayne Brown]

Somethings not right here the make up of the floor is not one I have come across minimum cover is normally 75mm sand and cement screed or a pumped flow screed over the pipework , dont know how far you have got but a overlay system may be a better choice as attached you can tile straight onto it ? no need for slc , please check before carrying out any further work .

 

[EatingSnakes]

Yup.
See my previous thread on the topic.
The original plan was to have overlay boards and then tile on top but it turns out I've got 28-30mm space to fill between the tiles and concrete so I was recommended the mapei renovation screed.

 

[Wayne Brown]

When did you post the thread please ?

 

[EatingSnakes]

DIY overlay boards for ufh - https://www.tilersforums.com/threads/diy-overlay-boards-for-ufh.88175/

 

[Wayne Brown]

Dont skimp bud this will bite you in the arse , how far have you got ? How much is there to make up between tampered concrete slab and tiled finished floor , look at the underfloor heating company website and their overlay system

 

[EatingSnakes]

I've got 28-30mm space to fill before the adhesive/tiles
Not looking to skimp.
I've bought 12 bags of renovation screed based off forum recommendation. Happy to do anything you guys recommend.

We ruled out overlay boards befause none come in 30mm thickness without having to stack on top of other types of boards.

Even if overlay boards were possible... The screed would give a better heat spread.

 

[Stu Lilley]

Mapei eco prim T plus is the one Mapei will recommend....I’m sure primer G will be fine but I would stick to what they suggest

 

[Boggs]

A low profile overlay heating system is what you need, something like Warmup Total 16,(others are available), where the pipes are laid in the grooves of the insulation boards, then you can use latex over the top.

 

[J Sid]

Dont skimp bud this will bite you in the arse , how far have you got ? How much is there to make up between tampered concrete slab and tiled finished floor , look at the underfloor heating company website and their overlay system

Wayne, I've already gone down that route and @EatingSnakes isn't intrested

 

[Wayne Brown]

Have to disagree overlay is the way or as Boggs has suggested the systems we have recommended you tile straight on top of the pipe heat is there instantly its seems julian has advised the same type of system 3 of us cant be wrong ? All the best kop

 

[EatingSnakes]

I could put overlay boards down but then I'll have to increase the floor level will mapei renovation screed anyway.

So why not use the renovation screed to begin with?

It is one of its listed applications.

Cheers

 

[Wayne Brown]

No you won't 18mm grooved boards with pipe laid and tile directly on top of the board and pipe , adhesive and tile will give you the 30mm . Kop

 

[EatingSnakes]

Its 42mm to the finished floor.
To the tiles and adhesive its 28-30mm

For overlay boards to work I would need a 30mm overlay board...

Or

...use a standard overlay board and top it with Mapei renovation screed, hence the suggestion to skip the middle man and go with the mapei reno screed to begin with.

 

[WetSaw]

You still need insulation under the pipes not under 4" of concrete otherwise the majority of your heat will be lost.

 

[Boggs]

Are you planning to lay heating pipes directly to your concrete without insulation beneath them?

 

[EatingSnakes]

This system was recommended to me by the underfloor heating people so that the heat is retained in the slab and slowly releases throughout the day.
It wouldn't be lost, there's 100mm king span underneath and 50mm king span on all 4 sides.

My only issue is that there's 42mm between concrete and finished floor.

Thanks again

 

[Boggs]

That’s a new one on me.
25 years and only ever installed wet systems on PIR boards.

 

[EatingSnakes]

Well its my first time but I've spoken to three plumbers and 2 ufh companies and they weren't phased by it so must be a thing.

With respect to the screed, I sought advise from the ufh company after I realised my concrete wasn't high enough and they told me there was no right or wrong way to do it but regular screed was out of the question. they said I would need a specialist thin screed with fibre.
I rang some local screeders and they wanted an arm and a leg to come out. The mapei screed was suggested at this stage.

there was a concern raised as to whether or not the Mapei screed would be OK at just 12mm above the pipes. This is a valid point. I'll ring Mapei about it in the morning.

If someone can suggest another way to get me up 42mm to my finished floor or a disadvantage of the renovation screed, the 12 mapei screed bags are probably still returnable.

Thanks for all the help thus far.