Cement rendering questions...
 

On Jan 29, 1:54*pm, "AL_n" wrote:
I need to render (with sand & cement) 30 square metres of exterior
blockwork.

I have done a little cement rendering in the past, but not much. Can anyone
advise the best mix of sand, cement, and possibly lime and/or plasticiser
that will give best workability?

1:1:6 (lime, cement, sand, by volume)

How much I will need, for 30 sq mtrs?

You can calculate the volume. Density is around 2.2.


NT

Many thanks,

Al

Cement rendering questions...
 

NT wrote in
:



1:1:6 (lime, cement, sand, by volume)

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

How much I will need, for 30 sq mtrs?

You can calculate the volume. Density is around 2.2.

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

Cement rendering questions...
 

AL_n wrote:
NT wrote in
:



1:1:6 (lime, cement, sand, by volume)

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

How much I will need, for 30 sq mtrs?
You can calculate the volume. Density is around 2.2.

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?


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
1/4 tonne of cement - that's ten 25kg bags - and about 5 bags of
hydraulic lime, to give it a bit of plasticity.

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.




Thanks..

Al

Cement rendering questions...
 

On Jan 30, 1:39*pm, The Natural Philosopher
wrote:
AL_n wrote:
NT wrote in
:

1:1:6 (lime, cement, sand, by volume)

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

How much I will need, for 30 sq mtrs?
You can calculate the volume. Density is around 2.2.

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?

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
1/4 tonne of cement - that's ten 25kg bags - and about 5 bags of
hydraulic lime, to give it a bit of plasticity.

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.

Thanks..

Al

1 cc weighs around 2.2g. I wouldn't use 1:3, you want the render to
fail when something moves, not the bricks. 1:1:6 is nothing like 1:3.


NT

Cement rendering questions...
 

On 30/01/2012 14:22, NT wrote:
On Jan 30, 1:39 pm, The Natural
wrote:
AL_n wrote:
wrote in
:

1:1:6 (lime, cement, sand, by volume)

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

How much I will need, for 30 sq mtrs?
You can calculate the volume. Density is around 2.2.

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?

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
1/4 tonne of cement - that's ten 25kg bags - and about 5 bags of
hydraulic lime, to give it a bit of plasticity.

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.

Thanks..

Al

1 cc weighs around 2.2g. I wouldn't use 1:3, you want the render to
fail when something moves, not the bricks. 1:1:6 is nothing like 1:3.


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?

Cement rendering questions...
 

On Jan 30, 2:35*pm, stuart noble wrote:
On 30/01/2012 14:22, NT wrote:

On Jan 30, 1:39 pm, The Natural
wrote:
AL_n wrote:
*wrote in
:

1:1:6 (lime, cement, sand, by volume)

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

How much I will need, for 30 sq mtrs?
You can calculate the volume. Density is around 2.2.

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?

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
1/4 tonne of cement - that's ten 25kg bags - and about 5 bags of
hydraulic lime, to give it a bit of plasticity.

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.

Thanks..

Al

1 cc weighs around 2.2g. I wouldn't use 1:3, you want the render to
fail when something moves, not the bricks. 1:1:6 is nothing like 1:3.

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

Cement rendering questions...
 

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

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
1/4 tonne of cement - that's ten 25kg bags - and about 5 bags of
hydraulic lime, to give it a bit of plasticity.

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.


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

Cement rendering questions...
 

NT wrote in news:1db91c33-64b0-45b1-98fd-
:

1 cc weighs around 2.2g. I wouldn't use 1:3, you want the render to
fail when something moves, not the bricks. 1:1:6 is nothing like 1:3.


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

Al

Cement rendering questions...
 

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

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
1/4 tonne of cement - that's ten 25kg bags - and about 5 bags of
hydraulic lime, to give it a bit of plasticity.

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.


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...


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.





Al

Cement rendering questions...
 

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


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.


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

Al