Rendering an external curved wall

[woodburyboy]

I've finished constructing a block wall with a radius on the boundary of my property. I think I may have boobed on my scratch coat with 5:1 sand cement ratio when it should have been 4:1. Can I get away with a 5:1 finish coat or should I weaken it to 6:1? The wall faces roughly west in the SW of England and is 1m - 1.5 m high

Also I have used a 3 in 1 admixture rather than lime for the first time. Is it safe to continue to use this on the finish coat, or should I use lime instead?

One final question - I have set a s/s bead up on the top edge to act as the top screed For the bottom screed I cut strips from a UPVC facia board and screwed these to the wall, plumbing it from the top screed. Therefore I should be able to create quite a decent curve using my long (1.5m) plastic float. Best will in the world I know it's not going to be perfect, so should I finish with a dry (damp?) sponge?

Thank you for any help or advice.

Mark

 

[Micilin]

I've finished constructing a block wall with a radius on the boundary of my property. I think I may have boobed on my scratch coat with 5:1 sand cement ratio when it should have been 4:1. Can I get away with a 5:1 finish coat or should I weaken it to 6:1? The wall faces roughly west in the SW of England and is 1m - 1.5 m high

Also I have used a 3 in 1 admixture rather than lime for the first time. Is it safe to continue to use this on the finish coat, or should I use lime instead?

One final question - I have set a s/s bead up on the top edge to act as the top screed For the bottom screed I cut strips from a UPVC facia board and screwed these to the wall, plumbing it from the top screed. Therefore I should be able to create quite a decent curve using my long (1.5m) plastic float. Best will in the world I know it's not going to be perfect, so should I finish with a dry (damp?) sponge?

Thank you for any help or advice.

Mark

Just make the top coat a bit weaker - even a couple of shovels of sand extra in the mix .

If your admix gave you a nice bit of gear, carry on - just don't put too much in - as it will make it not nice to rub up. Lime would make it nicer, and I would use it where possible but there is no need if you are happy without it.

The PVC is a good idea to give you a curve. Make sure water can't get behind the stop bead if it is exposed - mastic behind it, or put a fillet of render (this can be stronger ) over it to throw the rain off.

You should be able to rule it off and float it off to give a nice curve( I've never used a float that big so can't comment) and a final sponge will make it nice. Try the sponge dry or damp, see what you are happy with for the texture. Makiing it roughly uniform is more imprtant than the specific texture, as long as you find it okay.