render and set celcon blocks

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spunky

Private Member
Mix 2 sand 1 cement in a mixer you'll get about 6 shovels in mix it fairl wet then chuck in 2.5l of sbr just get a mate to hold something up to protect windows etc but you'll drop a bit so pretect the floor ....and it hurts after a bit lol
 

essexandy

The Lake Governor
This reply to only to be read by proper plasterers not DIY'ers or chancers. I've done plenty of externals and hundreds of internals over Celcon and Thermalite blocks and have never had any problems. I really don't think there is any need to slurry or Rendaid these blocks and you definitely don't want to be soaking the walls before hand. Give the walls a light spray before the scratch coat but once you've got the scratch done you must keep the render moist by spraying for at least three days, five being the ideal. Also when rendering over lightweight blocks getting the strength of your mix and thicknesses right is more important than ever. DO NOT MAKE YOUR MIX TO STRONG.
 

Freerider

Member
Cheers andy, thing is, finding time to spray the wall for 5 days is not worth the hassle! Id rather not take on any more rendering if its so much hassle! Dont get paid enough for it! Cheers anyway geezer!
 

irish_spread

Private Member
This reply to only to be read by proper plasterers not DIY'ers or chancers. I've done plenty of externals and hundreds of internals over Celcon and Thermalite blocks and have never had any problems. I really don't think there is any need to slurry or Rendaid these blocks and you definitely don't want to be soaking the walls before hand. Give the walls a light spray before the scratch coat but once you've got the scratch done you must keep the render moist by spraying for at least three days, five being the ideal. Also when rendering over lightweight blocks getting the strength of your mix and thicknesses right is more important than ever. DO NOT MAKE YOUR MIX TO STRONG.


True, I agree. In an ideal world this would be the way to do it, but on your typical (well London anyway) 12x10 extension you would need to scratch outside the 1st day, float and set inside the next and then rub up a week later. You cant keep popping back to mist down the scratch. I've done 100's by scudding and never had a comeback
 

bubbles65

Well-Known Member
Yeah, I always 'scud' them and never had a problem...............new word to me though - 'scud':RpS_thumbup:
We just 'splatter-dash':RpS_biggrin:
 

nickelarse

Private Member
if ur gonna sbr slurry get in in a gorilla tub and get a shitty soft broom and brush it on. or use gyprime or microgobitis
 

spark2010

New Member
EXTERNAL : good soak down with water day b4 if possible, then lightly hose about 20 mins before scratch. BS is 5-1 for therms on the scractch coat (with feb/waterproofer), Then 6-1-1 (lime, no admixtures), no need for pva it remulifies in contact with water/render. Also if u soak them down and the PVA hangs around... if u try to apply the scratchcoat, it will slide and the bond will be broken between the render and the therms.

NO NEED FOR REND AID / SBR, why would you try to make a key on a block wall that already has a key (high suction block), but its a good point Irish_Spread made about the SBR blocking the pores...
 

Freerider

Member
EXTERNAL : good soak down with water day b4 if possible, then lightly hose about 20 mins before scratch. BS is 5-1 for therms on the scractch coat (with feb/waterproofer), Then 6-1-1 (lime, no admixtures), no need for pva it remulifies in contact with water/render. Also if u soak them down and the PVA hangs around... if u try to apply the scratchcoat, it will slide and the bond will be broken between the render and the therms.

NO NEED FOR REND AID / SBR, why would you try to make a key on a block wall that already has a key (high suction block), but its a good point Irish_Spread made about the SBR blocking the pores...

Because you are killing the suction to make them ok to render, there fore it requires a mechanical key!
 

spark2010

New Member
see what u mean freerider, but i use SBR 2/1 and harl it on dense backgrounds, but a thermalite block has a key might not be mechanical but its a key...SUCTION...

I rendered the inside of an extension which was therms, soaked the wall down, then again before application.. nice thick scratch with admixtures and thinner top... that was about 4 months ago, went back last week... no cracks and its absolute solid. It didnt pull in quick nothing, in fact the scrtch coat hung around longer than expected...My mate who was with me tried to pva the walls after i soaked them down and i told him not to. He PVA's his wall and the scratch was sliding everywhere and wouldnt go off...

Im not saying the above method is the only way, but if you understand and control the suction then it works. You can make the suction work for you instead of using SBR/rend aid

There is only so much waster a block will hold after continous hosing
 

nickelarse

Private Member
Because you are killing the suction to make them ok to render, there fore it requires a mechanical key!

sorry mate your wrong. for example gyprime is designed to go over high suction blocks to be topped with hardwall. it doesnt create any key, just kills the suction
 

Freerider

Member
I thought if you killed suction completely, it wouldnt stick, thats like hardwalling over paint, which wobt stick.

I know what gypprime does mate, i didnt think it killed ALL the suction though. Either way i dont know why Im wrong? We were talking about killing ALL the suction externally with SBR, therefore the render needs a key, render won't stick without a good key or suction.

Spark - you seem to be thinking I dont understand that suction is a key in itself? I have been plastering long enough to know how it works dude ;) the issue here is that celcons/thermalites have too much suction to control, so working out a way round it, if you know what I mean? thats good, you must have managed to soak it just right! But from my experience and most of the guys above, no matter how much we soak them, the scratch still dries out to quick, therefore killing all the suction and using a mechabical key can make life eaiser! But each to their own, whatever works best for everyone!
 
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nickelarse

Private Member
sorry mate, i thought you were on about inside. was going by the thread name.

i think it depends on if the gear puts a glaze on the blocks or not. what i dont no tho is why for inside gyprime is fine, which has no aggregate in it, and yet outside any primer needs to be keyed. suppose plaster sticks better?
 

Freerider

Member
No probs matey, I think its as simple as that, plaster sticks better, but to be honest, like ive said before, so much stuff contradicts one another in building game!
 

beddy

Well-Known Member
shut up nick you cun.t.


oh and i see sparks back. hows the new career as a spread going me old china?
 

nickelarse

Private Member
im gonna ride u steven, and make u finger my bum with ur numb fingers.

cheers for calling me back btw w**k*r
 

irish_spread

Private Member
OK, FOR THE LAST TIME :mad:

You mix the sbr IN THE SLOPPY S/C MIX, then throw it at the wall with back of ur trowel. It looks a bit like sparse pebbledashing-hit and miss. You still have suction from the bare bits on the blocks and a mechanical key from the scudding


Im off down the pub :flapper:
 

beddy

Well-Known Member
ill numb your bum alright.

yeah about calling you back....i was busy banging your mum, or are we not allowed to say that anymore incase someone gets offended?
 

nickelarse

Private Member
how dare u say that to me steven. i thought this was a forum to help people. and all i get is u giving me s**t. i think i shall be reporting you.

oh, and my mums dead, cheers steve...
 

beddy

Well-Known Member
i do apologise nicholas. i shall not insult thee again. 4/5 screws in a row on a 6x3. 2 coats of pva, 2 coats of multi, scrim the screw holes aswell as joints, stick external beads on with dab.

anything else my dear
 

nickelarse

Private Member
does fingering ur bum with ur numb fingers make it feel like someone else is doing it, like when u sit on ur hand and then have a wank?
 

beddy

Well-Known Member
totally. but then because i couldnt feel it i forget i did it, forget to wash my hands then after my tea i pick food out of my teeth...
 

nickelarse

Private Member
heres a funny story talking about bums and and mouths. i was on holiday a few yrs back staying in a room with a mate, and i was giving hima bit of a hard time like u do, and he got a bit emotional when i had a pube trim and put them in his sponge and face cream and hair wax. anyway, next day he goes, i got u back, but wouldnt tell me why or how. when i got the photos developed a week or 2 later, one of the pictures was my toothbrush up his arse.
 

bodplasterer

Active Member
lol I was working on a site a few years ago and there were 2 chippys trying to get each other all the time and one of em stuck his mates pencil up his ass about 20 mins later the other chippy had it hanging out his mouth :-0 Another funny one was the dude i work with pissed in another spreads water butt on site and he came in first thing and washed his face in it wrong but funny :RpS_laugh:
 

Freerider

Member
Pmsl thats wicked, ive got covered in piss a few times picking up buckets without being told they are the bog!

Back on topic btw lads, is EVA an option for killing the suction externally on thermalites? Couple of coats of external grade pva?
 
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