# Forum Home Renovation Cladding  Blueboard wall.  Advice needed

## Danny.S

Hi Everyone 
I plan to build a Blueboard wall soon and am after some advice on the best way to treat the joins.  I was hoping to use a texture paint rather than render which I have used before and was happy with. 
What do you use to fill the joins if painting the sheets?    If I use an acrylic render instead can I just render straight over the joins with no treatment prior? 
Any help would be appreciated. 
Danny

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## mikeyg

> Hi Everyone 
> I plan to build a Blueboard wall soon and am after some advice on the best way to treat the joins.  I was hoping to use a texture paint rather than render which I have used before and was happy with. 
> What do you use to fill the joins if painting the sheets?    If I use an acrylic render instead can I just render straight over the joins with no treatment prior? 
> Any help would be appreciated. 
> Danny

  Hi Danny 
IMO the best way to treat blueboard joints is a 3 part system, similar to plasterboard. You should leave a gap between sheets when you put them up.. about 3mm. If you've already put them up and butted them right together, you might be able to run an angle grinder down the join to get the required gap. This allows for expansion and contraction due to changing weather conditions. 
There are products on the market to do the joints, but what you want is a base coat to fill in the recessed edges, & while it's still wet, embed a fibreglass tape into the base. Push it in with a broad knife & let it dry. Then a wider coat of the top coat over that join, and another even wider coat of the top coat again. Sand between coats, and try to sand as soon as it dries, because sanding it after a few days if mighty tough! 
Good luck & don't forget to let us know how you get on & if you run into any trouble.

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## Swerve

Good advice Mikey, will be doing the same later this year.

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## shauck

Best you have a long hard read of this PDF. It says to butt them up hard together unless you have a control joint (which by the way, is a butt join and not a beveled edge join) or others, such as construction joint, etc. Control joints have bond breaker tape behind them to separate from frame before a sealant is filled into the gap. Anyway, lots more to it and you should read it before you start.   HardiTexSpecification.pdf

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## r3nov8or

> Best you have a long hard read of this PDF. It says to butt them up hard together unless you have a control joint (which by the way, is a butt join and not a beveled edge join) or others, such as construction joint, etc. Control joints have bond breaker tape behind them to separate from frame before a sealant is filled into the gap. Anyway, lots more to it and you should read it before you start.   HardiTexSpecification.pdf

  +1.  
Read it. Do it.

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## Danny.S

Thanks everyone.  
I will read this article before going any further.  Have already put up the 12 sheets and butt joined.   
Danny

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## shauck

> Thanks everyone.  
> I will read this article before going any further.  Have already put up the 12 sheets and butt joined.   
> Danny

  12 sheets at 900mm = 10.8m or 12 sheets at 1200mm = 14.4m  
for either of these you will need control joints every 5.4m.

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## Danny.S

Thanks everyone 
Oops, didn't use a control joint.  Wall is just shy of 13M (12 and a bit sheets).  All sheets butt joined except at 3.6M where there is a 6mm gap.  The gap is not a control joint though, the supporting wall is one piece.  Bit late to change so I guess we will find out what happens.

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