Snowcrete Render - Top coat only

[kingandy2nd]

Hello guys,

Sorry if this sounds like an obvious question but I can find an answer anywhere.

I want to render my house with snowcrete to reduce the on-going maintenance.

Can I get away with only using snowcrete for the top coat only, or should the scratch be done using it as well? If I can restrict it to the top coat it'll save me some cash.

I was think of a scratch coat about 10mm thick and a top coat of 8mm. Does that sound about right? Walls are nice and straight to start with.

Thanks!

 

[roughcaster]

Scratch it with ordinary portland cement/sand scratch coat,, leave it a few days to set and cure, then use Snowcrete/sand for render top coat. Don't forget to measure each batch to get a consistent colour,, and dont forget the plasticiser/waterproofer in each batch either.

 

[kingandy2nd]

Many thanks for your input roughcaster.

I have being doing some research and have seen that one person mentions that a render top coat with snowcrete should be 8,1,1 or 6-1 with plasticiser instead of lime. The LaFarge website does say "Snowcrete has a higher final strength than ordinary Portland cement".

Do you think it sounds reasonable to use those ratios? I'm thinking the 6-1 with additives.

Also I want a white render as the finished product. I've send conflicting arguements recommending silver sand while others suggest white rendering sand. Do you have a view on this?

Thanks!

 

[roughcaster]

I think that 8 to 1 is pushing it a bit in my opinion. I would go 5/1 if it was me, 6/1 at most. The only time i've used Snowcrete as a finished render is on window/door reveals, the rest would have been as a white top coat, ready for roughcasting onto. We also added lime to lighten up each batch, so it was 5-1-1. I can't comment on the use of the white or silver sand, maybe the other lads on here can helo.

 

[cotswoldbuilders]

Scratch coat, 4 sand to 1 cement, float coat 5 sand 1 cement, option of 1 lime to each mix.
Stick to plastering sand.

 

[kingandy2nd]

Thanks again for your time roughcaster and for your input Cotswoldbuilders.

What reason do you suggest sticking to plastering sand for?

I really want the finished render to be pure white to compliment our grey window frames, and I'm not sure plastering sand will come up white if used.

Thank you.

 

[roy c]

Plastering sand is for rendering , silver sand and building sand are too fine for rendering.

 

[cotswoldbuilders]

The sands you mention are to fine and not enough grit to hold the mix together, it would probably break/dust up.

 

[kingandy2nd]

Ok, thanks very much guys.

So is there such a thing a white plastering sand? I've done a quick google but it doesn't come up with any good links to such a product.

Or should I use normal (yellow) plastering sand and adding something else to get a while render - I.e. an additive?

Thanks again!

 

[Alastairreid]

White silica sand is what you are looking for.

Have you considered K-rend?

 

[kingandy2nd]

Thanks Alastair.

I have seen the k rend products but i understood that k rend was applied by machine and they don't do a smooth finish, which is what I'm aiming for. Am I wrong?

 

[Alastairreid]

Can get both hand or machine applied..

http://www.k-rend.co.uk/portfolio.aspx

http://www.k-rend.co.uk/media/Application Instructions K Rend.pdf

 

[kingandy2nd]

Thanks for the links there.

I'd doesn't look to me like the k rend is desinged for a smooth finish, apart from the brick rend - but I think the cost of doing the 3 layers of k rend would be prohibitive.

Any other general advise for me if I'm looking to go down the snowcrete/silica sand route?

 

[1john]

You can top coat k-rend over a S&C scratch. It can be troweled up too I think but someone will confirm.

 

[kingandy2nd]

Thanks John, just found out that k rend is 12 a bag, and requires a bag per m sq....so puts it out of my price range for an option.

Cheers
Andy