Cement rendering questions...

You can calculate the volume. Density is around 2.2.

NT

NT wrote in news: snipped-for-privacy@cd5g2000vbb.googlegroups.com:

Thanks... Should it be sharp sand, or will any building sand do? (for optimum stickability, while wet.)

Sorry, I'm not familiar with the density factor; can you clarify?

I calculate the volume to be 0.5 cubic mtrs.

Can anyone tell me the volume of a 25kg bag of damp sand?

Thanks..

Al

that about 3:1 so .08 cu meters

What yer man is saying is that half a cu. meter of goodies is gonna be a shade over a ton = I'd buy a tonne and a half meself - of stuff.

Of which 1 tonne will be sand (I like sharp for render - nice rustic feel) and the rest a mixture of cement and possibly lime.

if you go for a 3:1 mix which is quite 'strong' you need something like

That takes the total up to about 1.375 tonnes in all, which is probably what half a cu meter weighs.

HOWEVER bear in mind that 'tonne bags' are often only about 875kg or so..so you may find you need a bit more sand in the end.

get yourself a tonne bag of sand, and then buy the lime and cement as needed. Unless you think you can render that much in a couple of days.

at this time of year use a frost additive as well.

This is where a trade account and delivery from a builders merchant is worth considering.

NT

I notice some very large Readymix silos on a building site near here and it says "lime mortar" on the outside. What's all that about? Can they be bricklaying with it?

I've heard of mortars called lime than are cement based with some added lime, and thus behave nothing like genuine lime mortar. I don't know which the readymix one is, but given that bricklaying with real lime mortar is so problematic, odds are its cement with lime.

NT

The Natural Philosopher wrote in news:jg66jd$or4$1 @news.albasani.net:

Very helpful - thanks. I'm thinking of more like a 5:1 mix. Thanks for the account suggestion; I do have an account at Jewsons, and I do remember them saying they deliver. That'll save some aggro...

Al

NT wrote in news:1db91c33-64b0-45b1-98fd- snipped-for-privacy@b18g2000vbz.googlegroups.com:

I agree completely. 1:1:6 sounds about right for this job. Thanks.

Al

Well then get that tonne of sand and a few bags of whatever and some winter mix, and play around with ratios till it feels right.

This is not an ideal time of year for rendering.

It can take a couple of days to set. Mild and damp is best. Subzero is awful.

The Natural Philosopher wrote in news:jg6pjb$3tr$5 @news.albasani.net:

I'm planning well ahead. Wild horses wouldn't drag me out there at this time of year. ;-)

Al

Much better if you can wait until no risk of frost.

Also, don't touch the surface for 6 weeks - it takes that long before it reaches full strength and it's easily marked before then.