Render volumes for 2.7sqm walls

[virgilns]

Hi - going to render part of a wall (2 x chimney alcoves) this weekend and have two 2.7square meter 'walls' to cover. At 15mm thick that equates to 2 x 41litres of 'render' - I presume aplied in two coats, one to flatten the wall (old house, bricks all over the place) and a finish coat to leave it flat for plastering.

Do I just measure out 41 litres of plastering sand and cement in the right ratio and add water or does the mix 'shrin' 'as the water is added...if it does - is there a formula for working out how much dry mix to make x amount of wet render?

Don't want to come up short and have to re-mix in the middle, but don't want loads left over....

Cheers,

Virgil.

 

[virgilns]

No one got any magic formulas for working out render qtys ?

 

[stevethespreader]

1 bag of sand does approx 1 and half m2 m use 4-1 scratch coat 5-1 topcoat lay on scratch coat and scratch it so you have a key for the float coat long wavey lines like this ~~~~, lay on float coat and devil scratch ready to recieve skim in figure 8 so it looks like this 88888 use a plasticiser

 

[ImperialCompleteSolutions]

If your doing such a small area I would use weber OCR (one coat render) 1 bag equals 1sqm at 15mm, so obviously you will need 3 bags ! Will be able to do it in one hit rather than scratch and come back later, plus I find it easier to rub up and get a smooth Finnish !

 

[virgilns]

1 bag of sand does approx 1 and half m2 m use 4-1 scratch coat 5-1 topcoat lay on scratch coat and scratch it so you have a key for the float coat long wavey lines like this ~~~~, lay on float coat and devil scratch ready to recieve skim in figure 8 so it looks like this 88888 use a plasticiser

Thanks. That helps a lot! presume a bag is 25kg? so a bag of sand per coat effectively?

plasticiser in both coats?

Cheers,

Virgil.

 

[virgilns]

If your doing such a small area I would use weber OCR (one coat render) 1 bag equals 1sqm at 15mm, so obviously you will need 3 bags ! Will be able to do it in one hit rather than scratch and come back later, plus I find it easier to rub up and get a smooth Finnish !

Thanks, but got the rest of the walls to do after this so probably best if i get used to measuring it out

 

[stevethespreader]

1 bag of sand does approx 1 and half m2 m use 4-1 scratch coat 5-1 topcoat lay on scratch coat and scratch it so you have a key for the float coat long wavey lines like this ~~~~, lay on float coat and devil scratch ready to recieve skim in figure 8 so it looks like this 88888 use a plasticiser

Thanks. That helps a lot! presume a bag is 25kg? so a bag of sand per coat effectively?

plasticiser in both coats?

Cheers,

Virgil.

yes use plasticiser in both coats
[EDIT] on the devil scratch use a float with nails in and dont make the scratch to deep

 

[virgilns]

Thanks, Steve. Presume it's worth 5-1 PVAing the walls first to stop the suction?

 

[stevethespreader]

Thanks, Steve. Presume it's worth 5-1 PVAing the walls first to stop the suction?

damp the walls down with water dont be shy with it

 

[virgilns]

Cheers guys. Did a wall tonight and went well...mixed 4 bags of sand by hand in a plastered buket...not ideal, but for there in the end!

 

[virgilns]

Well, 23 bags of sand later and I'm still going...I recon on about 13sqm, but the wall is about as bad as you could get for rendering (straight) I guess. Some bricks are 3/4" out from others, so there's probably about 25mm of render in some places!

Im pretty happy though - wall is perfectly flat and now plumb...wasn't miles out of plumb, just a million miles away from flat!!

Will be using hardwall on the airing cupboard side of the wall as want to have a go at full plaster...

got myself a new trowel and polished the edges ready for the skim coat as my render float (as it is now) is pretty rough...

going ok though...

 

[stevethespreader]

Well, 23 bags of sand later and I'm still going...I recon on about 13sqm, but the wall is about as bad as you could get for rendering (straight) I guess. Some bricks are 3/4" out from others, so there's probably about 25mm of render in some places!

Im pretty happy though - wall is perfectly flat and now plumb...wasn't miles out of plumb, just a million miles away from flat!!

Will be using hardwall on the airing cupboard side of the wall as want to have a go at full plaster...

got myself a new trowel and polished the edges ready for the skim coat as my render float (as it is now) is pretty rough...

going ok though...

upload some pics

 

[virgilns]

will do if you promise not to laugh

 

[stevethespreader]

will do if you promise not to laugh

promise take a pic of each stage

 

[Alastairreid]

Dont worry it would have to be a disaster for it to show up on a pic.