Celcon blocks render

[zzrmatt]

I'm a complete noob to plastering, managed to skim a couple of ceilings which came up ok but now have something slightly different.

I've just extended an internal wall using the same type of celcon blocks as the original wall. The original wall has about a 10mm render and then a plaster finish over this which I now need to blend into.

For the render would I be ok with two coats of 6:1 sand and cement with a dash of plasticiser and waterproofer to reduce suction on subsequent layers? Should the sand be plastering sand as I'm guessing building sand will be no use?

Sorry for the rather basic questions

 

[DominoRemoved]

plastering sand/builders sand is fine the thing you need to controll is the suction by weting down the wall first or even use pva
For dust/suction controll
id say 5:1 mix dash of plasticiser/water proofer is fine
devil float it then skim
ie float & set
backing coats: bonding hardwall browning sand/cement even mp75 formally known as wickes one coat plaster to.

 

[warriorupnorth]

Six to one is fine mate , don't bother with waterproofer , just plasticise, and one coat at ten mill will be ok , just wet the wall down a tad before you start

 

[martinemj]

don't use building sand


six to one is ok with nice washed plastering sand


for internal work on clecon block use hardwall or toughcoat #



ww.emjenkins.co.uk

 

[owls]

building sand?
do you know the difference between building sand and plastering sand d*m**o,and why building sand is made up of larger particles.

 

[warriorupnorth]

Yep sorry missed that bit , not building sand

 

[bodplasterer]

For a novice sand and cement is not the easiest thing to do if its on celcon blocks there should be a cavity so hardwall would be more suited and easier to use.

 

[lucius]

I aint done S&C on thermalite or Celcon for years but the spec ime sure used to be 8 and 1, but i stand to be corrected.

 

[DominoRemoved]

you can 4:1 lol

 

[Gibbo]

no you cant

 

[martinemj]

d*m**o 4:1 too strong for celcon/thermalite

6:1-7:1 more like it


we always use hardwall on thermalite ....as these are high suction backing plasterers they are made for the job .....

s/c messy to mix and apply ...why would you wan't to use it???