sand & cement

Status
Not open for further replies.
C

christ

Private Member
done a small bit of flat rendering the other day for a friend. there was a bricky on the job and i was a bit unsure about how to make a mix of S&C so i ask him and he said to put a little bit of fairy in the mix. is this right

cheers. also got a week off :o
 
itll split the particles in the mix and make it creamier and lighter to use , plastercisers cheap you can buy it from youre local merchants mate :)
 
theres reasons not to use fairy but i cant remember them exactly...think its something to do with cracking but its not recommended although it works really well as a plasticiser...puts air in the mix, gives it body, without it your mix would just slide off your hawk and youd prolly give up on rendering before youve even started...like nicksey says, plasticiser is dirt cheap, even waterproofer/plasticiser (rendamix type stuff) is only about 6 quid for 5 litres...
dont tell church you been usin fairy tho... :-X
 
read the instructions mate if youre using lime in youre top coat you'll need less poss a quarter of a mug full if not up to a mugfull, you dont want to over plastercise it because it can weaken the mix play around with it mate you want just enough to help the mix bind and cream up a little and dont over mix it!
 
back of the jewson stuff im usin at the mo goes something like 'dilute 40:1 with guaging water and use only this water for the mix, use only enough water to produce a workable mix which produces a more dense render'...others do it by weight of cement, like 1/2 litre to 25kg cement...
in practice what im doin (internal) is 3/4 macdonalds coffee cup waterproofer/plasticiser in 1 builders bucket of water, 1/2 bag opc (measured with a stanley knife if you know what i mean) 3 lime, 18 sand...tip the mixer forward slightly to get it off the back, add a bit more water if need be (up to another 1/2 bucket), 2 mins and in the barrow...
not gonna be too far out with that and its easy to guage...when it comes out the mixer you should be able to drag a shovel through it in little hoops easily and they should stay put...
top coat use 1/2 the waterproofer and im just throwing 1 lime in ( i should really be reducing cement too but 1/2 a bag gives you a good 6:1 on a mixerful so 1/2 bag opc+3 lime = roughly 6:1:1)
 
yeah nice ill just buy plastercisers, also how are external beads attatched. cheers
Click to expand...

I find electical clips are excellent for fixing all beads on external, except onto concrete lintels then you gotta drill, plug and screw using washers or bits of lead.
 
try banging 30/40mm galvo clouts into a red rawlplug...uses a 5.5mm bit (so u can get away with just about any old cordless hammer drill) and they pull up solid as f'ck...
something that pulls up supertight in brown plugs are polynails (plastic headed stainless steel ringshanks for plastic fascia boards)..they do not wanna come out...ever...
 
ps...put a straight edge and a level down yer beads as yu fix em off or theyll be all over the place...render beads bend dead easy...
 
yeah nice ill just buy plastercisers, also how are external beads attatched. cheers
Click to expand...
I use a PULSA 700P for fixing beads on concrete, but you do get them straighter if you stick them on, HP12 does the trick externaly.
 
hp12's a backing coat for krend mate its really sticky goes off nice and quick but it can be remixed to make it wetter without any probs, not sure of the price any ideas anyone?
failing that you can stick beads up with sand/cement, you have to be confident and press the dab onto corner/drip or itll just fall straight off
 
i spoke to a bricky the other day and he said beading can be fixed while applying scratch coat, just push them on to s&c
 
in an ideal world brickys would make all walls perfectly level and then i can see sticking angle beads directly to a 6mm scratch coat working ........in the real world you can be 20mm out and you wont get enough purchase on the scratch coat
 
Sticking the bead in scratch is a way old trick,but only really works if you use stop bead for every corner and angle!
 
not a huge fan of using render to stick beads on unless its a dead straight forward bead up one day, scratch the next day job... get within 10 feet of em before its rock hard and they come off again and when in full swing you dont really wanna be arseing around with loose beads...
 
theres reasons not to use fairy but i cant remember them exactly...think its something to do with cracking but its not recommended although it works really well as a plasticiser...puts air in the mix, gives it body, without it your mix would just slide off your hawk and youd prolly give up on rendering before youve even started...like nicksey says, plasticiser is dirt cheap, even waterproofer/plasticiser (rendamix type stuff) is only about 6 quid for 5 litres...
dont tell church you been usin fairy tho... :-X
Click to expand...

lol  fairys not a good idea really its been banned from sites for years, using a mcdonalds coffee cup for waterproofer though top idea ;)
 
Well ever site agent , clerk of the works, and arceitect on site that ive worked on for the last 15 years its a no no, it make the render brittle and puts to much air/ bubbles in the mix trust me its not a good thing to use.
 
use waterproofer mate..its also a 'retarder/plasticiser' means if your on a straight concrete block job you can throw it on in one coat (long as its not tooooo thick) then rule the whole wall, loads of time, makes a perfect job...you wanna see the bleedin walls im on at the mo...bone dry is too nicer word for em...its 'scrape-stiff brush -hosepipe -scratch - float coat...absolutely no option' still, ive always used waterproofer in my float coat, gives me loads of time, so i can put loads on then do something else whilst i wait for it to suck...(im goin against the grain tho)...thing is, ive always skimmed it green...left a wall an extra day last week before i skimmed it, the waterproofer had cured and i had it with board finish....never ever had it so easy in my life...church? im thinking do it this way and let it cure then i can stick shitloads of skim on?? long as its devil floated right can you see a problem???
 
there will be no problem if you skim it a week later all you have to do is give it a slight wet in before you start skimming just let the water go in a bit so the wall looks damp not wet ! this will start the waterproofer in the render to work and give a slow even suction
 
yeh thats what i thought...ive just got set in my 'must skim it green...must skim it green' ways...purely cos skimming old render you have to soak it to saturation and/or pva the hell out of it...
never before tried skimming 'cured' - 'waterproofed' render...learnin all the time..
swear to god though, the difference was unreal, i could have put 3 times the skim on and still got a perfect finish...green render always keeps me fit, maybe 3/4 set size compared to board..
shame its prolly the last decent size render job im gonna get for ages again now...i was really startin to enjoy the change....
still, if the customers happy with this phase (seems well pleased so far though cash flow is an issue, he's a plumber with 4 kids and it seems to have hit him the same way its hittin some of us) and i get the next bit...painted/coated/friable/patched 4m ceilings, been damped...13"solid again...massive room...should be fun!!! :P
 
Status
Not open for further replies.
Back
Top