Render or render effect over plasterboard around a woodburner nook & pillars?

[joidevie]

We've just had a room plasterboarded - a mix of boards glued on with MAP, and some rail work (ceiling mainly).

We have a fireplace 'nook' with a canopy which has been plasterboarded with pink placos, including the fireplace surround (pillars, built from cellulose blocs, but now covered in the placos). Inside this 'nook', we plan to have a wood burner, which will have ample space around it.

What we're hoping to do is 'render' (or coat) the space behind the woodburner and the surrounding 'pillars' in a 'stone like' finish (or render like) to make it less smooth and 'perfect'.. To make a sort of fake stone look (hopefully quite convincing!).

What might we use? I have doubts a simple lime mortar will stick, or just crack at a later date.. Or just fall off..

What about a classic plaster like 'Lutece' (mixed with a little sand, and some PVA on the boards as a bonding aid?).

Or a 'Weber' type crepi product which might have some resin additives to help with flexibility (and heat effect)?

Or an 'out of the tub' type crepi?

We're trying to use as many natural products as possible and are painting our walls with home mixed limewash (with pigments etc.), so would like to retain a nice 'organic/rustic' feel where possible!

Any thoughts? 

[richard51]

From your post you know lots more about plastering etc than I ever will.

However, in our stone fireplace we had a backing just behind the burner that was concrete(I think) but was painted black, the same colour as the fire insert.

Would a metal backing from an antiques/secondhand place also be another possibility?

[Théière]

If you are looking for an authentic looking stone finish not painted then using bags of patrimone from bricos would do the trick. It's finely crushed stone with a polymer cement binder and cannot be differentiated from limestone blocks. Available in Tours and Angers tones around our region, others may vary

[joidevie]

Thanks Théière..

Would you apply this straight onto smooth placo, or should I consider stapling some fine (7mm squares) mesh onto the board first as a key?

Or apply a PVA or other 'primer?

Thanks also for the other suggestions!

[oemodm]

I used fireproof plaster, ensuring the join between regular and fireproof plaster was at least 2m from heat source to prevent (contraction) cracking between the 2

[idun]

So what colour are you going to paint this crepi??? Nuances of grey????

If you can  get some for a very 'warm' area, that is.

I ask as crepi, as you say is an uneven surface and frankly there is dust and soot with wood burners and the crepi could end up looking very shabby/mucky in a relatively short space of time.