fix someone else's work!

[BARRONBATHROOMS]

hi all, been to look at a job I should of done last Christmas but couldn't fit in. custard Ended up using someone else but it has caused no end of problems. Now he as asked me if I can put anything right! Kitchen/dinner is 36m 2 of crap slate effect ceramics. He wants me to re grout floor as it look like it was cleaned off with a mop! I know won't be able to get grout out without chipping or scratching tiles. I presume I wouldn't be able to go over existing grout. Never tried to do any repairs before was looking for some advice! He is a friend of local builder we get plenty of work from so wanted to help if I can. Both bathroom travertine floors have cracked and the workmanship in general is pathetic feel so sorry for him. One more thing how long do I need to leave a screed floor to dry before tiling

thanks again

[Stewart]

You should easily be able to remove the grout without chipping the tiles if you use something like a Fein saw with a suitable blade in it.......

What type of screed is it....?


Created on iPad.....

[Dave]

How long have you left new floors in the past..?

[man of kent]

Stripping out grout is never an easy option, there's a gadget on the market called a Fenn, I think that's how its spelt. It's a vibrating disc which works. The screeded floor needs to be left for a MINIMUM of 2 weeks, preferably 3.(If the screed shrinks after you've fixed the tiles, ill the tiles shrink as well????)

[Dave]

Stripping out grout is never an easy option, there's a gadget on the market called a Fenn, I think that's how its spelt. It's a vibrating disc which works. The screeded floor needs to be left for a MINIMUM of 2 weeks, preferably 3.(If the screed shrinks after you've fixed the tiles, ill the tiles shrink as well????)

you might want to check the specifications on that...

[BARRONBATHROOMS]

I would normally leave for at least 8 weeks but he wants to be in for Christmas. Don't want to lay onto screed too early as I like to do the job once and get it right.

[man of kent]

Very cautious, the BS advises a minimum of 2 weeks, preferably 3 for a sand cement screed.

[young1066]

a bosch multi tool (£59 on amazon) comes with a grout removal tool its the only thing i have found that works without damage and does it quickly,before that i wouldnt touch re-grouting, n&c do grout cleaner that will take vertually anything of a floor.as for the screed, a good week but you still have to check there are no damp spots as it varies on ambiant tempreture

[Dave]

Very cautious, the BS advises a minimum of 2 weeks, preferably 3 for a sand cement screed.

Are we talking bs5385 ?

Min is 1mm per day for first 40 mm and then 2 days per mm greater than first 40 mm.

[timeless john]

Of course a green screed adhesive could be the answer, but if the screed cracks then so will the tiles.

[garybadger]

Marcrist have just brought out a grout removal blade. Very thin so it fits into a 2mm grout joint.
It fits onto a normal angle grinder. Not had the pleasure off using one as yet as only noticed it in the shop yesterday. Think its about £40 plus V.A.T

[man of kent]

BS 5395-3 2007
C.1.9 Eliminating construction moisture
COMMENTARY ON C.1.9
Although ceramic tiles are unaffected by constructional water, concrete
bases and screeds shrink as they dry out and can produce sufficient
compression forces to break the adhesion between the tiles and bed. It is
therefore essential that a proportion of the drying shrinkage of the
concrete base and/or levelling screed is allowed to take place before fixing
tiles.
Structural concrete should be subjected to continuous air drying after
the end of curing for at least six weeks before either a levelling screed
or a tile bed is applied to it. A longer period might be necessary in poor
drying conditions. Cement:sand and fine concrete levelling screeds
should be cured for at least seven days and be subjected to continuous
air drying after curing for at least two weeks before the tiling is applied.
A longer period might be required in poor drying conditions and/or
where the floor is to be heated. Where the bed is laid over a separating
layer, as described in 7.2.3.3 the need to allow some shrinkage to take
place before tiling is less important as movements in the base or
levelling screed are not transmitted to the tile bed or tiles.

[Dave]

So you don't have BS5385 then... that is what governs tiling..


You need to make sure a screed is dry to 75% relative humidity , so in theory a screed containing portland cement that performs to BS-EN 197-1:2000 is allowed to firstly cure for min 7 days and to prevent the surface drying to quickly..

Then it is left a further 2 weeks to dry out...min 21 days before tiling BUT the screed will still be green and then a moisture test can be performed to test humidity within the screed if you wish to tile the standard way.

You can tile after 3 weeks but not with standard adhesives unless the screed has heating and you forced dried it but that cannot commence till 21 days anyway...

So as John has said you can use a green screed adhesive at 21 days or a vapour equalisation membrane but not standard adhesive as the screed could curl from this point onwards and debond the tiles.. a green screed adhesive will allow for shrinkage and expansion and so will the vapour equalisation membrane.

But to tile as normal IMO is asking for a failure, we are all here to learn and everybody learns something new....

Hope that helps..

[BARRONBATHROOMS]

Thanks for you detailed advice much appreciated. Have only been tiling a few years and my knowledge is limited to bathrooms really. But I've done a bathroom and wetroom for a custard and he has asked me to tile a big open plan kitchen/ livingroom/ conservatory over 2 different substrates screed and suspended flooring. Just making sure I do my research before I decide if I'm confident enough to do job. Again thanks for your advice about screed and removing grout.

[waterfd]

Have you thought of a decoupling membrain such as Ditra I seem to remember they talk about green sceeds in their literature. and with different sustrates it may be advisable.

[man of kent]

Thats the problem when you get old and have large fingers!!!!!the 8 and 9 are very close together on my keyboard!!

[man of kent]

Tiling on 'green' screeds is not advisable, a screed needs to shrink to its final dimension
before you tile. Ditra is a good product, just make sure that if there is any timber as part of the floor, that it is well braced and dimensionally stable prior to fitting the Ditra.

[BARRONBATHROOMS]

Will be recommending ditra to client. Also as it is a large area approx 80 meters I presume i need expansion joints? How do I work out how many. I have read about them and think I understand the reasons I will need them. But have never fitted them before? Thanks to everyone for there input. Nice to know there are people willing to share there knowledge with people like myself who haven't got as much experience.