Rendered Blue Board v Rendered Hebal

[norveb]

Hi, I am currently considering having the cladding removed from our house and replaced with a rendered Blue Board (I understand that you can buy Blue Board already rendered and ready to paint) however I have recently been made aware of Rendered Hebel which apparently has better anti cracking properties at the joints and corners. Could I get some feedback on the two products.........Much Appreciated norveb

[brynk]

gday norveb

blueboard that i have seen comes primed and ready to receive an acrylic render, which dries on at about 1.5mm thick & allows for movement of the substrate without damage to the coating itself. there is also a product that comes already painted called vitrepanel which is pretty good but each sheet requires an expansion joint/gap - some designs use this as a feature - regardless, the fibre cement sheet (colloquially, blueboard) requires meticulous attention to the expansion joints to accomodate the movement caused by temperature changes - this movement must be allowed for in the framing (ie, must not be rigid), as well as the board itself, otherwise the board will crack where it is fixed off to the frame. the acrylic render will hide some of the smaller cracks but large ones will show through. blueboard must have an interior wall with an airgap and an allowance for drainage/weepholes/etcet, otherwise you'll get condensation in winter.

hebel is an autoclaved aerated concrete block that provides bloody good insulative properties, but it requires a cement render also to seal it from the weather as well as protect it from damage (during construction, the corners of the walls must be protected as it will not take much to knock a good chunk off!). the render must have more than the usual expansion joints because if movement is not allowed for between the different materials then it will crack. once it cracks, the water ingress will get in behind the paint and the render, and you will get large water bubbles, flaking, etcet. (i was on a ten-storey job that suffered from this problem - ouch!)

what is your existing cladding?

r's brynk

[norveb]

Hi Brynk,

Thanks for the detailed info, I believe that the existing cladding is Hardy Plank which was installed about 15 years ago..............Regards norveb

gday norveb

blueboard that i have seen comes primed and ready to receive an acrylic render, which dries on at about 1.5mm thick & allows for movement of the substrate without damage to the coating itself. there is also a product that comes already painted called vitrepanel which is pretty good but each sheet requires an expansion joint/gap - some designs use this as a feature - regardless, the fibre cement sheet (colloquially, blueboard) requires meticulous attention to the expansion joints to accomodate the movement caused by temperature changes - this movement must be allowed for in the framing (ie, must not be rigid), as well as the board itself, otherwise the board will crack where it is fixed off to the frame. the acrylic render will hide some of the smaller cracks but large ones will show through. blueboard must have an interior wall with an airgap and an allowance for drainage/weepholes/etcet, otherwise you'll get condensation in winter.

hebel is an autoclaved aerated concrete block that provides bloody good insulative properties, but it requires a cement render also to seal it from the weather as well as protect it from damage (during construction, the corners of the walls must be protected as it will not take much to knock a good chunk off!). the render must have more than the usual expansion joints because if movement is not allowed for between the different materials then it will crack. once it cracks, the water ingress will get in behind the paint and the render, and you will get large water bubbles, flaking, etcet. (i was on a ten-storey job that suffered from this problem - ouch!)

what is your existing cladding?

r's brynk