Rendering solid wall

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theplasterer

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Hi,
I've looked at a job today and basically the guy has an old house with 18" solid walls, in the last ten years he's had it rendered twice (externally) and both times its blown. He wants it rendered again with s/c (he doesn't like mono). I wondered if anyone would suggest the appropriate method of rendering.
I'm not sure whether to use that rendaid stuff first then scratch it with 3-1 with fibres then top it out with 4-1 without fibres or would you mesh it with the rendaid coat? What you use lime in both coats also?

Any suggestions would be great.
Thanks Dan
 
Hack back to brick work, apply splatter coat,this would be 3/1 sand cement with sbr in the water at 2/1, next day apply waterproof coat,sand cement ratio 5/1 with fibres, possibly an embedded mesh, keep damp for a week, with a nice key for second,
apply second coat 6/1/1 sand cement lime with one handful fibres, keep damped for a week..
 
Thanks John, with it being a solid wall I wasn't sure of the mix ratio, everyone has a different method/ratio.
Some say put more cement in and others say more sand in, some say don't leave it too long before you top it out because it wont bond to the scratch coat if its got waterproofer in it. People use so many different methods its unbelievable.
 
bobby said:
John do you go back every nite for a week and damp each coat down.? Surely not!!!
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No, usually damp as we are working inside or passing or get the owners to do it, would not pay to do it otherwise, weather been a factor too..hot weather needs hessian cloth to stop drying.but who will pay..?
 
theplasterer said:
Hi,
I've looked at a job today and basically the guy has an old house with 18" solid walls, in the last ten years he's had it rendered twice (externally) and both times its blown. He wants it rendered again with s/c (he doesn't like mono). I wondered if anyone would suggest the appropriate method of rendering.
I'm not sure whether to use that rendaid stuff first then scratch it with 3-1 with fibres then top it out with 4-1 without fibres or would you mesh it with the rendaid coat? What you use lime in both coats also?

Any suggestions would be great.
Thanks Dan
Click to expand...
Rendaid it mate , times have moved on
 
Personally I go with which ever is more cost effective, never had a problem sbr slurry and rendered a lot of cobb, stone and old brick. That said though rendaid is a good product
 
I use a sbr slurry and then a coat of 5:1 with water proofer. Let set and dry a bit and second or more scratch coats with each coat being slightly weaker than the previous.

Not sure about rendaid with sand and cement on top? I would prefer Rendaid and mesh it if it is normal thickness or fully mesh the first scratch coat and stress patches in any other scratch coats using Weber ocr.

Getting the Customer to pay for it is something else. How about sending pics to Weber of the substrate and thicknesses required and get them to spec (ha ha) then you are covered if you provide their email spec to the customer first.

I did a similar job and I used membrane fixings on the full mesh. If it wanted to blow the whole mesh was pinned back. The customer was really fussy as this was his third attempt so I went over board to show there was not much I could do.

That was 2 years ago and no problems.
 
Thanks lads, Its quite a big job, 2 gables and maybe the front of the house, I'm not sure what the 18" walls are made of, its just what he's told me. You can see where the render has blown but none of it has actually fell off yet. That webber ocr I think will be too expensive for what he wants to spend, its maybe 40m2 each gable and the same for the front at a guess. so that's 120m2.

When you say mesh I take it you mean the fibreglass stuff and wheres the best place to buy it from TP or online.

I like the sound of the ocr but I think the cost will put him off the job.
 
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