Wall chaser, with just one disc mounted and with vacuum extraction, will do a quick neat job.
(TBH, I think I would just chance tiling over - its only a screed and hence unlikely to move if the slab stays put under it)
On Saturday 28 December 2013 03:58 John Rumm wrote in uk.d-i-y:
Hi John,
There is celotex under the screed and over the slab - so some possibility of movement if the celotex compresses. I'd not be worried if the screed were on the concrete directly.
Cheers
Tim
tile it :>)
Jim K
On Saturday 28 December 2013 03:58 John Rumm wrote in uk.d-i-y:
Been sleeping on this...
Wall chaser with the VAX on the back will probably not be too bad.
Anyhoo - look what I found:
Stitching is certainly a professional technique.
It's not expensive either... Now I only have 2 questions for the manufacturer (I'll ring them next week):
1) Will that resin eat my UFH pipes?2) I have to bridge a 50mm wide weak area, not just a crack, so can those strips be overlapped for longer lengths.
Option B is to go back to the idea of using 2-3mm (to suit angle grinder slot width) stainless threaded bar as the straps:
in which case, I wonder if the Uzin resin would be better compared to injecting
The latter sticks like ***t - I've used it before. However the Uzin resin will probably penetrate the screed a little which might be better. Might be another question for Uzin.
The proposed solutions are overkill imho. SS tie bars, such as the overpriced helibars, would merely shift any movement crack a bit. Non-SS EML would cause premature tiling failure.
The options I'd consider are:
NT
On Saturday 04 January 2014 13:02 snipped-for-privacy@care2.com wrote in uk.d-i-y:
What do you suggest for thin epoxy? I only know epoxy in the form of araldite and epoxy DPM...
Have a look at the West Systems range... they do their basic epoxy as quite a thin runny stuff, that you then add fillers and thickeners to if required.
Beat me to it.
Also SP do a low viscosity long cure epoxy that flows well.
NT
Do what I did. pour (half a gallon of) liquid PVA down the crack and then leave it. sorted about 2 sq meters of wobbly screed.
in 48 hours it was all stable and I tiled over.
12 years later and its still fine.On Saturday 04 January 2014 16:36 The Natural Philosopher wrote in uk.d-i-y:
You may have missed my reply last time:
Your screed was on concrete, yes? So glueing it together would probably work.
Mine is on 3" celotex which of course has some give.
Or better still, half a gallon of SBR
On Saturday 04 January 2014 18:17 stuart noble wrote in uk.d-i-y:
That won't do it. Normally I would be considering that - but not in this case.
Everyone seems to be missing the bit where the *screed is on top of celotex*.
Like this:
SSSSSSS||SSSSSSSS CCCCCCCCCCCCCCCCC BBBBBBBBBBBBBBBBB BBBBBBBBBBBBBBBBB
B = convrete base C = celotex (75mm)
S = screed
|| = crack
C is not *very* compressible, but it is compressible
If a high load is applied to the left or the righ end of the screed, there
*is* going to be some turning moment which will try to open the top of the crack. Normally the microfibre additive sorts this out - but not, apparantly, if you introduce a weak strip due to filling in the trough left by a levelling pole.This is why I think staples/tie bars are probably the best bet.
John's original suggestion of helibars may have been a little OTT (those things are seriously structural) but it it exactly the type of suggestion that led to some interesting goggling - coming up with the same idea but in minature - small ties. Searching around those seems to suggest they are a standard solution, along with the other suggestion here of a decoupling mat.
Cheers,
Tim
This is why you need a uniform bond all along the crack, hence epoxy not bars. PVA is not gapfilling.
NT
No
So glueing it together would probably
no mine was on 60mm of polystyrene
sure is in enough quantity..
TBH the helibars are rather uninspiring when you see them - a couple of mm thick at best twisted stainless rods.
On Sunday 05 January 2014 19:23 John Rumm wrote in uk.d-i-y:
Really - they looked like 1/4" or more...
Not the ones I have seen (*) - they are quite skimpy looking. Massive tensile strength compared to masonry though, so you don't really need much.
SS EML or wire are far cheaper. Or just sliced up scrap SS.
NT
On Sunday 05 January 2014 22:47 snipped-for-privacy@care2.com wrote in uk.d-i-y:
You need soemthing with a texture - that's why I'll probably use threaded bar.
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