Make life easy, search the forum.

Discuss Sand & Cement wet room floor screed questions in the Tiling News; Tile News area at TilersForums. USA and UK Tiling Forum

Please checkout the following advertisement.
Hi All.
Got to admit, having to use S&C to form a wet room floor is a first for me. I Got a call out of the blue from a builder who I have never come across ,quite a few other things setting off alarm bells....... Painter already in an adjoining room,waste pipes at a jaunty angle,promises of we will do this,we will do that.......
but what is the minimum thickness of sand and cement required and how long would this take to dry? Just what to be sure of my facts when I ring him up.
 

Ajax123

TF
Arms
Reaction score
933
Re: Sand & Cement wet room floor screed questions

BS 8204 part 1 is the standard that covers sand cement screeds. The situation you are talking about would be an unbonded screed (I.e. on a polythene membrane or in direct contact with an unprepared concrete slab)

The minimum depth at any point in domestic situations is 50mm and it MUST be reinforced with either d49 steel mesh or polypropylene fibres.

If it is on insulation I.e. Floating then it would be minimum 65mm and if bonded you can go to 25mm but the base must be prepared by shot blasting or grinding to remove the Laitance to expose the coarse aggregate in the screed.

- - - Updated - - -

Is Ajax watching the England football or out making a 2nd living!

Cant stand footy so been out ... Sadly it was a non paying event.... :)
 

Ajax123

TF
Arms
Reaction score
933
Would tanking first before the S&C screed is laid, inhibit the drying times of the screed?

You would be better priming the concrete underneath with an acrylic primer or SBR to limit the level of moisture into the concrete. You should technically cure the screed for seven days under polythene but if you lay it and cover it for a couple of days you would be able to use a liquid DPM on it. This will "trap" the residual moisture ( it will dry eventually) but under the DPM it will do no harm. Just make sure you put a suitable perimeter edge round it to prevent moisture migrating into the surrounding materials (walls, other screed etc) the DPM should be laid and dry sand broadcast into it before it dries. When dry vac up any remaining sand tank the walls as normal and then tile using your usual flexi https://www.tilersforums.com/forums/tile-adhesive/. Sounds like a lot of work but it's only a small area so will not take long or present much effort IMO .
 

Ajax123

TF
Arms
Reaction score
933
Oh and use a plasticiser in your screed to aid compaction and make sure it is not too dry.... So many screeners use sand cement screeds that are too dry... Causes real issues with compaction.
 
OP
M

Mr Tiler

Wow what a lot to take in ajax... About the perimetre to prevent the screeds moisture spreadin tho. Whats ideal to use in your opinion? And once that void hasbeen created and the perimetre removed... What do you fill that void with? And is there an expansion joint needed in this situation if so what is it? Very informative thanks mate
 
OP
T

Tilegods

You can take screed down to 30mm if needed but usually 50mm on concrete base with a few fibres thrown in for good measure and a slurry with sbr onto the base will insure a good grip.
You can take sand and cement down to 0mm . Use a 4mm notch trowel and spread tile https://www.tilersforums.com/forums/tile-adhesive/ when going 10 amd under
 

Kevbos

Arms
Reaction score
36
Hi All.
Got to admit, having to use S&C to form a wet room floor is a first for me. I Got a call out of the blue from a builder who I have never come across ,quite a few other things setting off alarm bells....... Painter already in an adjoining room,waste pipes at a jaunty angle,promises of we will do this,we will do that.......
but what is the minimum thickness of sand and cement required and how long would this take to dry? Just what to be sure of my facts when I ring him up.
Sand and cement tile requires you being able to screed firstly !! And then being able to fix your tiles onto the wet screed , with what they used to do a neat cement fine slurry , it's the same as waterproof rendering , the scratch coat has to be finish coated whilst still wet , other wise the drying scratch coat becomes waterproof and finish coat does not bond !! Just a 4 part sand to 1 part cement should create a waterproof mix , but you must seal or moisten area prior to screening or rendering !! But that's old school tile , anyone that has tried to take this tile off floors or walls will know how good it is , but it is slow and not many can do it anymore !! It's not easy to do properly
 

Kevbos

Arms
Reaction score
36
Hi All.
Got to admit, having to use S&C to form a wet room floor is a first for me. I Got a call out of the blue from a builder who I have never come across ,quite a few other things setting off alarm bells....... Painter already in an adjoining room,waste pipes at a jaunty angle,promises of we will do this,we will do that.......
but what is the minimum thickness of sand and cement required and how long would this take to dry? Just what to be sure of my facts when I ring him up.
Sorry forgot to mention !!! The only reason noone does the best way of tile anymore is because of time aspects and the changes in building methods , there is I doubt not even 1 major house builder that has used sand and cement tile in there projects for 25 years , because of drying times , and the need for the use of solid walls or floors in the houses they build , to accommodate sand and cement tile !! I am a victorian tiler , and I see tile over 100 years old because of this method daily , and yet it not used nowadays !!
 

Reply to Sand & Cement wet room floor screed questions in the Tiling News; Tile News area at TilersForums.com

Or checkout our tile training advice or the Tile Standards

This website is hosted and managed by www.untoldmedia.co.uk. Creating content since 2001.
Please visit our sponsor websites, they keep the forum free to use!

UK Tiling Forum Stats

Threads
66,599
Messages
866,700
Members
9,508
Latest member
sj1709
Top
AdBlock Detected

We get it, advertisements are annoying!

Sure, ad-blocking software does a great job at blocking ads, but it also blocks useful features of our website. For the best site experience please disable your AdBlocker.

I've Disabled AdBlock