Page 1 of 1
Posted: Wed Mar 18, 2009 8:36 pm
by sako
Hello Chaps.
I have previously rendered a garden wall but after taking some of the timber grounds off without first slitting down the side of them with a diamond blade i have pulled some of the plaster off.So i have been looking at some of this SBR in the builders center and was wondering do you have to mix it like a slurry as stated on back of container or can you just apply it like you would pva ie mixed with water??.Spoke to a builder today who said the SBR he uses is just mixed with water and painted on,not sure of brand.Any help would be much appreciated.Oh he also said it was expensive but stuff in builders center was quite cheap really hope i am looking at correct stuff.
sean.
Posted: Thu Mar 19, 2009 6:46 am
by lutonlagerlout
not sure what you are trying to do sean,AFAIK the most important part of render is the waterproofer,if you need to make good a small area better to grind it right back ,rather than try and overlay a tiny area
cheers LLL
Posted: Thu Mar 19, 2009 9:52 am
by Tony McC
SBR is normally used in two ways:
a) as a slurry, made by mixing it with cement to the consistency of a thick pea soup and then daubing it on whatever it is that's being laid/rendered
b) as a mortar additive, where a measured amount is added to the gauging water when mixing the sand and cement
...I've never known it be diluted and then daubed on, though.
A good quality SBR will cost around 5-10 quid per litre, but it goes hell of a long way!
Posted: Thu Mar 19, 2009 4:02 pm
by sako
Thanks for the replies.Do you think it is essential to use this or pva as a bonding agent when rendering a concrete block wallI?I have seen some unibond pva will this do same job in helping render bond to block wall? I know some people use nothing at all.
sean.
Posted: Thu Mar 19, 2009 7:53 pm
by DNgroundworks
No bonding agent is needed on new, freshly built blockwork just needs a dust off and maybe a spray of water, bonding agents are generally needed on backgrounds with excessive suction or of poor key.
Id use PVA on old brickwork blockwork and the like.
And an SBR bonding agent/additive on weather bearing applications such as exterior rendering, And apparatley it can bond in damp conditions.
I wouldnt use PVA on a background that is wet or damp as its water soluble.
Posted: Fri Mar 20, 2009 1:04 pm
by sako
Thanks for the advise chaps.
sean.
Posted: Sun Mar 22, 2009 4:40 pm
by simonphillips
Hi
Ive always used Ronafix for bonding renders and screeds.
Mix it 1:1 with cement in a pot or bucket and brush or sweep it onto the wetted surface. Put the render or screed on before it dries. Works very time.
Ive tried pva and cheaper sbrs in the past. Pva always fails and things come unstuck and debond when they get damp or wet. Other sbrs have been hit and miss. Ronafix from Ronacrete costs a bit more, but its cheaper in the long run - well, it has been for me.
Hope this helps you guys.
Good website.