how to stop cracking when sand and cement plastering

[thechief13]

when i ve finished the sand and cement with skim finish i find the a couple of days down the line that little cracks appear, is there any way to stop this, i ve been told there is nothing i can do because they are drying out cracks any help cheers

 

[trowelmonkey1]

cracks from drying out would appear sooner than a couple of weeks IMO.

movement in the building maybe?

 

[thechief13]

may start showing before a couple of weeks. They are like little air line cracks, not really big enough for movement cracks i think.

 

[thechief13]

cracks from drying out would appear sooner than a couple of weeks IMO.

movement in the building maybe?

may start showing before a couple of weeks. They are like little air line cracks, not really big enough for movement cracks i think.

 

[Alastairreid]

mortar plasticiser or lime in the 2nd coat ? drying out too quickly! waterproofer in scratchcoat?
proper mix?

EDIT apologies i never read the post properly , thought you were talking about exterior rendering.

 

[Alastairreid]

i ve been told there is nothing i can do because they are drying out cracks any help cheers

See above.

 

[JohnD]

where I live, it is a common way to render a wall in sand and cement, then a skim of hard finish plaster (round here it used to be sand and lime as we are by the sea). I will look out for and old bloke and see what he says about drying times.

 

[Micilin]

where I live, it is a common way to render a wall in sand and cement, then a skim of hard finish plaster (round here it used to be sand and lime as we are by the sea). I will look out for and old bloke and see what he says about drying times.

I would say that when it was sand and lime, they used a lime finish?

I think that if you try a decent waterproofer in there with no lime, it is much better for skimming without any of those cracks. For skimming , plas instead of lime is better, IMHO.

 

[external]

try a weaker render mix ,id go up to 7 +1+1 for internal float coat ,forget the w/p and just give the wall a good drink on each coat,w/p is the devils brew and brings up more probs than solutions.

 

[Micilin]

try a weaker render mix ,id go up to 7 +1+1 for internal float coat ,forget the w/p and just give the wall a good drink on each coat,w/p is the devils brew and brings up more probs than solutions.

Have to agree to disagree here, I'd rather float out with wp and not worry about hosing down before skimming (although obviously that will work as well, as you know),espeically in an occupied house never had a problem although you have to let first coat pick up a bit as there is no suction -but teh whole wall is equalised Also as you go, you are damprooofing the wall/house

 

[wozza56]

How many coats of finish did you do ?

 

[Micilin]

.F

 

[external]

prolly right about a domestic job was thinking site,cant really use the the hose when the tellys on,but a good w/p float coat can take days longer to cure so is best left 5 days or so before skimming or as i've found you can get a bit of shrink and a few cracks.jmo

 

[joe-90]

Take a look at this.:

http://www.dolphinfloats.co.in/virgin-polypropylene-fibres.html

Strongplast (second down)