Sbr in ocr?

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camnz

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i was wondering if i could add SBR with OCR render.ive used it on a few jobs but get hairline cracks the other bag renders i used to use never cracked but the ocr is loads nicer to use, would SBR wake it a bit stronger/flexible and would it go off quicker?
 
everytime i have used cpi general bagged render i have had trouble with loads of hairline cracks, laying the top coat on a fully cured scratch coat.

would love to know the reason why as it has put me right off using it?????????????????!!!!!!!!!!!!!!!!!!!!!!!!!
 
Fcuk knows just seems to be so many products about these days that are marketed as fail safe and they aint, you all know my opinion on Mono its s**t, i can see us all going back to S&C at least you know what you are doing with it,
BRING ON ESSEX ANDY
 
CPI comes with 4 or 5 designation mixes. Consult their tech department about the des mix for the substrate you are spraying onto.We have just done 500 M2 on a house 2 ct work.Not had any problems. Watch the 2nd coat is not too thick as you may suffer tiny vein looking shrinkage cracks .
 
thats sucks .... its great render to use but cracks ,when i spray the hose on some walls the next day the cracks stick out like dogs nuts im out in oz and give the walls a mist of water as they dry during the day.they only have OCR 3 here wonder if OCR 2 would be any better?
 
Why not mix your own as we all should still be doing, its 100% cheaper and your in control of what your using. The mix i use is 5-1 sharp sand to opc and 1 pint of sbr in every mix. When i mix i gauge my sand and cement in small builders buckets and 5-1 is a full mix. I also mix in a large tub (half a water barrel) with my mixing drill i don't bother with cement mixers. I use the same mix for the scratch coat and top coat if its good enough for weber its good enough for me!
 
CKJ said:
Why not mix your own as we all should still be doing, its 100% cheaper and your in control of what your using. The mix i use is 5-1 sharp sand to opc and 1 pint of sbr in every mix. When i mix i gauge my sand and cement in small builders buckets and 5-1 is a full mix. I also mix in a large tub (half a water barrel) with my mixing drill i don't bother with cement mixers. I use the same mix for the scratch coat and top coat if its good enough for weber its good enough for me!
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Surely that'd take ages to mix like that, i tried mixxing sme in a groilioa tub before with my whisk, and it was a crap mix...You can always leave one in the mixer mixing to if useing a cement mixer..
 
s.p.t plastering said:
Surely that'd take ages to mix like that, i tried mixxing sme in a groilioa tub before with my whisk, and it was a crap mix...You can always leave one in the mixer mixing to if useing a cement mixer..
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If your adding sbr its recommended not to use a tumble mixer (see technical notes on any sbr product). It doesn't take any longer to mix with a drill i find it easier.
 
richardbrown said:
every job i have used it on i have had shrinkage cracks .... millions of them, scared to use the stuff now mark!
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Richard, are you two coating with it or tryng to finish it off in one day. We sprayed a new build in Kent 1 month ago.I had no problems apart from 1 elevation which had 4 or 5 small vein like shrinkage cracks. But I know that this part of the wall ended up being heavier on the 2nd pass .We look for 6 to 8mm on the top coat , float it in then finish with a fine sponge.Fine spray water at end of day if warm or sun light is aggresive.Used desgnation mix 2 on 7 newton light weight concrete block

Doing 150m on a front and gable end of this week. Des mix 2 again.Will let you know how it goes.

Mark
 
mark this was 3 coat work with each coat being allowed to fully cure before the next, the top coat i guess was 10mm thick and floated and sponged lovely then someone says ohh look theres a little crack there, and there and there and everywhere lol. i even rushed out and bought one of those back pack water sprayers to run about and keep it damp.



next day = road map rendering
 
Richard, was this onto a Lathing system of some kind( twil lathe or similar),and what was you design over all thickness for the 3 coats?
 
lol mr goblet does that make you the robot with a distinct lack of verbal diarrhoea then......mr twiggy......billybillybillybillybilly:flapper:
 
Its all crap just new ways and materials that dont stand the test of time, Mono being the worst, you cant beat S&C but even with that give it a coat of stabiliser and you will see the crasks.
 
using bagged pre blended renders cost a dam sight more than mixing your own i agree

for that extra cost i want my bagged render to be the dogs
 
if you want to do 2 coats with bagged use ocr2 for the scratch and ocr3 for the topping out.

cant see it being a problem adding sbr, weber will have their own version additive no doubt, giving it more flexibility and strength, usually it does go a bit quicker yes.
 
can you use OCR/rendaid insted of Parmurex and for the mesh scratch?can get lankolatex and mesh out here but not parex products
 
you can mesh with rendaid and then ocr over that but rendaid is a very high spec, only use it if you absolutley need to, it is in effect a slurry coat. no point if it is overkill, rendaid aint cheap and its very messy
 
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