Rendering

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fredfriedrich

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Been asked to render a 6 foot exterior wall
Need to confirm whether it's 1 part sand 3 parts lime?????

When do i apply the second coat???

how do i mix it up?


Cheers for any advice
 
this is what I use,

1/ scratch coat,,4 sand, 1 cem, 1 lime,waterproofer.
2/ floating coat ,, 6 sand ,1 lime ,1 cem.

Leave the scratch coat 72 hours to dry
 
Widdow how do you find it when topping with lime in scratch? As when ive used lime in scratch found it went off super fast. so what ive always used is 4 and 1 with waterproofer holme sand scratch and 5, 1 and 1 with waterproofer and holme sand top coat never had a problem with that, rubs up lovely.
 
sorri im new to S&C wot is the LIME? iv no it as
1 scrach coat /sand cement warter proofer
2 coat /sand cement FEB

iv not done much backing and rendering..not to sure how long s&C takes to set for rubbing up seem like hours and hours when ever iv done it.
 
hi bodplaster,

To be honest I have never had a problem with it going off too quick? what was the weather conditions like when you experienced this mate?
 
Im not sure what the weather was like as it happened along time ago, but im sure it went like this, we were top coating with our normal mix 5, 1 and 1 and had freak storm, it all went pear shaped so to pull it back we just scratched it all up, went back when weather was better and gave it a slight wet down as we normally do and laid it all on, by the time we got back on it to float it down it was sucking folid, it took buckets of water to pull it back, and i dont like the finish you get when you struggle floating up, looks all patchy, but it has happened a few times when you got a barrel of muck left over and just wack it on as a scratch found it has gone off quicker than the mixes without the lime, so we dont use lime in the scratch coat on big jobs maybe if its a small extension.
 
do i need to add a waterproofer if it's a free standing exterior wall.

the wall is 7ft by 18ft how much materials am i going to need??????????????????
 
no you dont need to use waterproofer but i would anyway, render is a protective finish and youll need plasticiser so a tub of waterproofer/plasticiser will set you back a grand sum of about 15 quid max..
quantities...ok, theres about 0.6 - 0.75m3 in a ton of sand
render goes on about 10-15mm thick if its pretty straight...
id say about 1/3rd of a ton of sand...
youll struggle to buy a third of a ton but you should be able to get 1/2 a ton at a smaller local builders merchant (not jewsons or the like cos they only wanna sell u ton bags or the little handy bags at £3 for 25kg), youll need a trailer or an empty ton bag, get em to dump the half ton in the ton bag and forklift it into the back of a medium/high roof panel van e.g transit...they wont wanna deliver 1/2 a ton but you might be lucky...
1/2 a ton should be around £15, dont get soft sand, get 'coarse building sand', sharp if you like but i prefer the stuff we get round here billed as 'building sand', the soft is norfolk...more like talc
4 bags of opc (ordinary portland cement) should do it...i a bit always get a bit more anyway...
if you want a good strong mix, nearly a full builders bucket of water (if the sands wet put less water in), 1/2 litre of waterproofer/plasticiser in a mixer, throw in half a bag of opc, 8 good shovels of sand, other half of opc, another 8 sand, should be nice and wet but not like curry, more like quicksand..thats about 3:1, youll need to take it off with a jackhammer...
throw in on in one coat, rule it off, let it firm up and float it.
it you wanna scratch it, do so..then top it in the morning still green
if you wanna add lime do that too, reduce cement accordingly...
this is for one side of said wall btw
it'll set very hard, light grey...
if you dont want/need it that hard, drop down to about a 5/6:1 and halve the waterproofer...it works on the cement content...
have you ever rendered a wall before? cos it aint as easy as it looks matey...
 
my god :-/
what can go wrong???????
that has terrified me
not my wall free standing garden wall
potential customer
im a plasterer but have never rendered (once at plastering school)
"Jackhammer"??????what???
What is most likely to go wrong?
 
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