# Forum Home Renovation Rendering  Cracking - Blue Board join movement or render problem?

## Monaro

G'day, 
Looking at buying a house with cracking evident in the render appearing in the blue board joins. Appears to be a rendering issue but not 100%. Anyone know of a blue board manufacturer or who's responsible for meshing the joints before applying the render? Is it the builders job to seal the joints before rendering or the renders?

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## johnc

Does it matter? The last thing I would be doing is buying someone else's problem. There is a correct way to fit blueboard with a gap and filler which is as important as the tape. Some builders get the joins a bit tight which causes cracking. It's an easy fix, pull off blue board, refix new sheet and replaster. All you need is very deep pockets, looking for the cause to asertain liability is something the vendor should be doing.

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## OBBob

Hi Monaro, there seem to be a lot of problems around similar to what you are desribing, so I would have thought a call to a rendering company would tell you if there are any long term fixes that are any good.  
I agree with JohnC, you'll end up stuck with the problem and pursuing a builder to fix it will probably be as much work as doing it yourself.  
Just find out whats involved, maybe someone has come up with a brilliant wonder product to fix it.

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## Tools

> Does it matter? The last thing I would be doing is buying someone else's problem. There is a correct way to fit blueboard with a gap and filler which is as important as the tape. Some builders get the joins a bit tight which causes cracking. It's an easy fix, pull off blue board, refix new sheet and replaster. All you need is very deep pockets, looking for the cause to asertain liability is something the vendor should be doing.

  While I agree that blueboard should not be tight against other surfaces or internal corners,the proper way to install the sheets is that there  should not be ANY gap left between them. 
Tools

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## Sir Stinkalot

Blueboard + Render = Cheap job. 
Not often that you see a classy house clad with blueboard.
Cheap, quick & easy. Looks good for a few years, helps with the sale and keeping the price down and then it looks shocking.

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## myla

hello, 
quick fix is to seal with sikaflex and repaint (2 coats), this an easy fix, keep sealant to a minimum on sides of crack 
whole lot could be re-rendered with appropriate meshing and render ($40/bag stuff) 
why blueboard cops it I dont know, am know currently patching/fixing a lot of polystyrene sheet clad houses where washers are coming through, angles peeling off, cracks etc 
when rendering blueboard I believe best to use "patch" render for joint with mesh and then skim whole wall with "patch" and mesh again wider than original 
doesnt take much longer but definitely holds up 
thankyou
myla

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## Rod Dyson

Blue board cracks because fibre glass mesh tape just doesn't cut it. 
Mind you the manufactures have not come up with a better jointing solution yet. 
I have blueboard on my own house that has the odd hairline crack as well. 
Even villaboard will develope cracks if fibreglass mesh tape is used.  Paper tape is the only answer for villaboard but I can't see it being used externally with the resin jointing compounds. 
Come up with practical solution and you will make money!!  (Maybe a hemp tape is the answer? It is stronger than fibre glass!) 
Cheers 
Rod Dyson

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## malachi

Rod you've got me worried about this mesh not being good enough, i'm going to texture coat a blueboard job(complete house)and have bought a couple of rolls of this mesh tape. You mention about the tape, but maybe the resin compound might be a problem,i went wattle paint shop they had the tape and an external joint filler that you mix, is that what you by resin compoun and if so would this be the way to go?

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## malachi

myla, you said skim whole wall with patch and mesh again,do you put the mesh first then skim wall?Joe.  

> hello, 
> quick fix is to seal with sikaflex and repaint (2 coats), this an easy fix, keep sealant to a minimum on sides of crack 
> whole lot could be re-rendered with appropriate meshing and render ($40/bag stuff) 
> why blueboard cops it I dont know, am know currently patching/fixing a lot of polystyrene sheet clad houses where washers are coming through, angles peeling off, cracks etc 
> when rendering blueboard I believe best to use "patch" render for joint with mesh and then skim whole wall with "patch" and mesh again wider than original 
> doesnt take much longer but definitely holds up 
> thankyou
> myla

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