External rendering over cement fibre board?????? Ask your questions and find answers on many subjects relating to plastering and dry lining

[Kenco]

Hi there
Brand new to this forum so a big hello to all out there.
I am in the proccess of building a house in the south of France, the construction of which is rather unusual!! It being a light weight steel framed construction.
My problem being that I have used a fibre cement board (Marley Eternit Duripanel) as the outer skin of the house and I now wish to render it.
I have done a bit of research on this and it would seem that the recomendation is to go with one of the new type thin coat silicone/acrylic type systems.
Whilst I'm sure these systems are "the dogs whatsits!!" they are also prohibitevely expensive!!!
They consist of a base coat. scrim, primer, adhesive and finaly, top coat!!
As I'll be working of moveable scaff towers, the labour involved in moving these the 3 or 4 times to achieve the finish is in its self financially a big NO NO!!
In an ideal world, I would like a one coat spray on render that would be suitable for (and adhere to!) the fibre cement board.
Obviously I do not want the render to crack, so I would prefere a degree of flexibility in the finish render, being in the south of France the temperature can range from -8 to +38 degrees c. (though hopefully not on the same day!!)
Any and all suggestions would be greatfuul recieved (short of knocking it down and re-builing in brick!!)
Regards to all
Kenco.

[stoneyboy]

Kenco,
The problem with this type of board is getting a secure bond to the board especially where it will be exposed. I suggest that the only way of using a normal cement screed is to first fix stainless laths over the outside of the boards and screed on this.
end

[Kenco]

Thanks for that, I was kinda hoping that there was some magical substance that could be "painted" on to the cement board in order to provide the neccessary key for the render, a bit like diluted PVA as you would paint onto interior plaster work in order to ensure good adhesion. Any comments??
Kenco

[stoneyboy]

Kenco,
Sealing the outside of these boards is a no no - they must be able to breath through the coating. How about using a micro-porous masonry paint, eg sandtex, I think this can be applied direct.
end

[TheDoctor5]

Last year 64% of the questions asked in our forum were answered within our DIY project pages at www.diydoctor.org.uk/projects.htm The project pages are now separated alphabetically and your answers are accompanied by diagrams and the ability to see, and buy, the tools and/or required to complete your project. Use our search box to look for your answer and save a great deal of time and money!

[Carl Rotheram]

[quote="Kenco"]Thanks for that, I was kinda hoping that there was some magical substance that could be "painted" on to the cement board in order to provide the neccessary key for the render, a bit like diluted PVA as you would paint onto interior plaster work in order to ensure good adhesion. Any comments??
Kenco[/quote] :lol:

Hi Kenco
There are a few different finishes for this application. A acrylic render can be applied on to the board as long as it as been primed with the right primer. The joints need to be taped before hand.
Another product Renotex rollercoat spray apply or roller. Apply cenent based bagging coat first