rendering timber frame

[ranger]

I have built a two storey timber frame extension, the bottom half of which is to be rendered to match the rest of the house.
The frame is sheathed and has building paper attached. To this I will be putting 2" x 1" battens vertically, then breatheable building paper, then stainless steel mesh and finally the render.
My concern is the flexibility of the timber frame and would ordinary sand and cement render be suitable, Should I be adding lime to the mix ?
A couple of local plasterers say no but I'm not convinced.

 

[1john]

how about attatching cement board over the battons, then the s/s eml then render? That would in my mind give a more stable background and definatly provide better knock resistance

 

[ranger]

See where youre coming from but would the render still be able to breathe?

 

[1john]

well as much as it would on a brick or block house, yes. the thing is you leave an inch or so gap by battening over you timber frame with breathable paper on, therefore creating a small cavity allowing your timber to breath with the cement board, eml and render over top, giving a stronger finish than just eml over building paper. with cement board over there is a much more firmer background for the render to bond to with a lot of help from the eml, if you wanted to be super posh you could key the cement board with SBR and sand first and then add the s/s EML. mega bonded and I would think it would serve you a long time.

I am sure someone with greater experience will be along to give you another angle and/or maybe shoot me down

 

[thatbloke]

whats the rest of the house rendered in ?

 

[ranger]

The original house is sand and cement rendered. the render on the bottom half of the extension has to match. The top half will be timber clad. I like the idea of cement board behind the mesh but there may be issues with adhesion as has been pointed out.
By the way, what thickness is the cement board and where would I get it. The only stuff I can find is for cladding purposes and is expensive.

 

[1john]

cement board is about 1/2 inch or 12mm ish, I would imagine most builders merchants will have it or can get it, knauf make it amongst many other manufacturers i would imagine, try getting into the depths of google for some info on suppliers near you.

 

[ranger]

Cheers, thanks for all the info