SBR Bond

[huddsspread]

Im an old skool plasterer ( 34 years old ) And when i am rendering i use sand,cement and waterproofer/feb. Sometimes i use wire ( render lathe to all you young spreads ).

But i have a job to do, and i am considerong using sbr bond on it first, as im always interested in new methods.

Its a painted concrete block wall, about 60m by 2m. It gets a bit wet from behind it and they want it rendered. The guy is a builder, and he seems to think that if i scratch and render it will be fine. But i really want to make sure the water don't come through.

After reading this forum i have thought about sbr bond, to paint over first, and then scratch ( wait till its tacky etc )

What i would like is your thoughts and advice. Should i knock up a sbr bond and cement sloppy paste? then paint it on? If i paint it on neat ill need about 12 tubs. I was also thinking of tanking it with tanking slurry first instead of sbr, giving it two coats, but how would that effect my Render after?

Any advice would be appreciated.

brad

if you look at the bottom right, thats a small corner of the block work-i have already rendered the brick work club, and they love it so much they want the wall doing too.

 

[Micilin]

Hudd

You can brush 1:1:1 OPC :SAND:SBR on and stipple as you go .

This will give you a key to render on to after 24 hours.

If coveering the surface, when you will seal it up and reduce the suction. Although you may have some 'green suction' if you scratch and finish with a day between coats

---------------------

Or you can mix 1:1 OPC and SBR to a slurry and render on to it when wet/tacky, and scratch, then finish as normal after 24 hrs . You won't be able to do much with the scratch coat as it will slide
---------------------
For a proper tanking job you would use the 1:1:1, then next day 1:1 and render coat, then next day 1:1 then render coat, getting waeker as you come out finishing 3:1 sand opc. You would also have SBR in the render mixes as per spec on tub.

----------
Whatever you do, ensure that your final coat is a uniform thickness ie do all your work in the previous coats.

And wear gloves, wash up ASAP on the slurry !!!!!!!

EDIT Don't need to tell you, but for readers make sure all loose etc removed and in warm weather it may need a drink first before the slurry

 

[huddsspread]

Thanks for that. I think i may go with the sand cement and sbr stipple slurry. As this will also give me a key to scratch. Any idea how far it will go? i mean a 5 litre tub of sbr bond, 5 sand and 5 cement ( for an example ) Mixed up as a slurrry? or is that too much sbr?

 

[chucka]

SBR is an amazing product for waterproofing. A few weeks ago I was doing the first fix wiring in a house and the forman brought along a tub of SBR and told the plasterer to give it a try "just use it as you would unibond" he was skimming over old plasterwork. Any way on it goes, waits for few minuets and on goes the multifinish. Then lots of swearing, no suction, the sbr waterproofed the walls so well the plaster would not stay on. I took the rest of it home as it was in the bin and I now use it to do things like priming wood before painting. amazing stuff as a sealer.

 

[chucka]

Hi huddsspread, can u take a look at my blog "dampproofing solid walls" and see what u think. I am trying to retain the heat but ventilate the walls. Thanks.

 

[huddsspread]

I actually have some sbr pva bond, as i walked in the local builders merchant as was meant to grab normal pva but grabbed pva bond. I just used it as a normal pva, and it didnt make things worse or better. Id glued up some old walls the night before and skimmed them the next day.

I read the tub and it seems its like pva for the outside ( as you cant use pva outside )

I want to use sbr AS a waterproofing slurry and as a key for my scratch.

 

[ghostdog]

hi I currently use weber rend aid as a scratch as it totally seals the background

http://www.netweber.co.uk/renders-d...raditional-mineral-renders/weberrend-aid.html

and you can use weber ocr as a top coat instead of sand and cement its so nice to use and you finish it the same as sand and cement

http://www.netweber.co.uk/tile-fixi...oducts/additional-products/weberrend-ocr.html

after using this I'm never going back to sand and cement
hope this helps

 

[stevethespreader]

---------------------

Or you can mix 1:1 OPC and SBR

do you use neat sbr mic or do you water it down say 2-1?

 

[Micilin]

---------------------

Or you can mix 1:1 OPC and SBR

do you use neat sbr mic or do you water it down say 2-1?

You can water it down as you say esp if not needed as a waterproofer, but spec says as above. It goes a long way especially if the background is damp so I would not skimp

 

[Micilin]

SBR is an amazing product for waterproofing. A few weeks ago I was doing the first fix wiring in a house and the forman brought along a tub of SBR and told the plasterer to give it a try "just use it as you would unibond" he was skimming over old plasterwork. Any way on it goes, waits for few minuets and on goes the multifinish. Then lots of swearing, no suction, the sbr waterproofed the walls so well the plaster would not stay on. I took the rest of it home as it was in the bin and I now use it to do things like priming wood before painting. amazing stuff as a sealer.

You are right about it as a sealer.

Very good as it is not affected by moisture , but is by UV.

HAte to be cynical but if he could not plaster onto tacky SBR - not a spread.

 

[roy c]

SBR is an amazing product for waterproofing. A few weeks ago I was doing the first fix wiring in a house and the forman brought along a tub of SBR and told the plasterer to give it a try "just use it as you would unibond" he was skimming over old plasterwork. Any way on it goes, waits for few minuets and on goes the multifinish. Then lots of swearing, no suction, the sbr waterproofed the walls so well the plaster would not stay on. I took the rest of it home as it was in the bin and I now use it to do things like priming wood before painting. amazing stuff as a sealer.

You are right about it as a sealer.

Very good as it is not affected by moisture , but is by UV.

HAte to be cynical but if he could not plaster onto tacky SBR - not a spread.

I did think along those lines aswell

 

[chucka]

Thanks for your comments on solid walls. I have a property which was built around 1900 which has solid walls but not as thick as this new property. The builders back then built a false wall on the inside. they used untreated timber and there is no rot to this day although the brick work is damp. My advantage is I am taking the roof off and putting a breather felt on then slates, so the roof space will be vented. if I can get the ventilation right, ie from under the ground floor behind the false walls up into the loft space using celotex and fibreglass and making sure their are no gaps (trusty foam gun) I think this is the best way forward. I might spray the solid walls before plasterboarding with a dry rot spray just to kill any spores ?? I have seen some nasty dry rot but it usually needs something to feed on

 

[roy c]

What dry-rot doesn't like is fresh air, a good air flow will not kill dry rot but will prevent it coming back after properly treated.