sand and cement

25 Jun 2008
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United Kingdom
Hiya is wall render (sand and cement) exactly the same as floor screed?

If applying screed onto recently laid concrete do you need to damp down with water or PVA the floor as you would with a wall?

Should you waterproof screed (if laying real wood floor on top)

Is wall render (internal) applied in one coat then scratched then finish plastered?

How thick should a render coat be?

Sorry for all the q's but I've seacrhed everywhere and there's not much info about sand cement rendering it's all bonding and browning info.

Any help greatly appreciated.
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qubit, you should start a new post, maybe a Mod will move it ?

is it the same = no.

yes wet the concrete with water before screeding.

never hear of it being waterproof before but others might know different.

odd times but mostly 2 coats.

10 to 20mm but I have loaded hollow wall out to 5 inches in a kitchen.
Don't put any additives in with your screed mix, if you order it from any suppliers who deliver it in 1/2 ton tubs then they will ask you what the screed is for and do you want "fibres" and a retarder in it. We usually get a 12- 24 hour retarder depending on size of job. Fibres are optional, sometimes we do sometimes we don't. When you are putting screed on to a concrete floor put some water into a bucket and add cement and mix into a "Slurry" and wet the floor area you are working on and paint the slurry on then put your screed on top and do that all across the floor as you move on.. We don't screed less than 30mm deep....Good Luck
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thanx Mr C spot on with the details so screeding is different from the bog standard wall render do you happen to know if internal wall render (sand and cement) needs 2 coats (1 scratch and 1 top) then finish or is it just scratch coat then finish (much easier) it's the INTERNAL side of an external facing solid brick wall and thicknesses that would be great please sorry one more q I'm screeding about 9m2 hopefully think shouldn't need a retarder right?[/u]
Entirely up to you with retarder, two coats on the wall, first coat 4 sand 1 cement, you can put a drop of w/proofer in the scratch, if its on a solid wall. It won't do any harm, and your floating coat you can use 5 sand 1 cement and 1 lime, (no additives) lay it on level it up, let it pick up and float it out with a plastic float with a few nails in it (Devilling) float it in figure of 8s and you will have a nice "key" to skim on... Before you scratch kill the suction on the wall either by giving it a soaking (water) or paint it with pva( 4-!1 mix) and scratch when the pva is tacky... Good Luck.... Take your time with the scratch and check levels as it is quite important to get it fairly true, it will save you a lot of messing about on your float coat.....
oh and enjoy the germany vs spain game I think Spain will destroy Germany, they deserve it
guess what
this button is for?
one more q I'm going to put in waterproofer in the render because it's on a removed chimney breast and don't want any problems with hygroscopic salts (absorbing rainwater from external side of wall) should I put in waterproofer in both coats or scratch coat only (don't want to use lime have no experience with it and hopefully lots waterproofer and sharp sand should be enough and don't have any lime) plz any replies thanks :rolleyes:
Just put the w/proofer in the scratch then, and read the carton and follow the amount they specify. If your not going to use lime then put morticiser in the float coat and follow the guide lines for amount...Ok ;)
OK Roy C thanks I was just thinking I'll put water proofer (called rendamix) in the float coat as well eliminating the need to use any mortisciser and extra waterproofing do you think I shouldn't do that then? Thanks Very Much :D

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