External Stucco / Cement render decorations - Any Advice?

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Hello,

Later this year I'm going to be building a shed with concrete blocks.
To make it a bit prettier I thought I would cover the external walls with cement render (Stucco?) and put some extra features on.

For example, quoins on the corners and for the windows I quite fancied a raised edge and a keystone on top.
I've seen this on a lot of older buildings and I think it looks really smart. I've often wondered how they did it in the past. Is there a proper name for this other than decorative raised cement render window mouldings?

I've read about two ways so far; one with polystyrene and one with wood.

Polystyrene allows for complex shapes but the idea of gluing polystyrene to a wall and then covering it with cement render sounds fiddly, messy and not practical. Also, I can't find any UK shops which sell polystyrene for external architectural features. (Plenty of US sites though, do we do it differently in the UK?)

I've also heard about features being made in wood. The wooden mouldings are screwed on, covered with a waterproof membrane with a wire mesh nailed on top to grip the render. To do it this way I'd be worried about the wood moving and cracking the render. I don't think this method would allow fussy details either.

I've attached a photo of the sort of thing I would like to
achieve. It seems to be popular on American buildings and old British buildings.

Does anyone have any experience with either technique? Perhaps there's another technique I should know about?

Finally, can anyone give me a definition of the difference between stucco and a cement render? The only difference I'm aware of is Stucco is a term usually used in the US.

Cheers,

Ian
 
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Yes! You're quite right. It is going to be needlessly over the top for a shed.

I love traditional architecture and I love woodwork. I thought I would combine the two and build a beautiful shed.

I'll be doing all the work myself so I'll only be paying for the materials.
 
You can buy all kinds of Quoins, corbels etc made from polystyrene and sprayed with a fleck texture to look like render.

However, for traditional render there are a few ways.

I would scratch coat first but the scratch coat must be ruled off flat and true.
Then for quoins You can form the quoins with timber.
Straight laths, PAR, with mould oil or similar .

Mouldings can be run with a template. Silver sand,lime OPC ,SBR mix will make final coats easy. 6mm ply will form an arch to work to. Plastic curtain rails are good for curved profiles or rebates in curved mouldings.

The window mouldings in your pic are based on Patent reveals , these can be formed in situ but often pre formed elements were stuck on.

Hard to go into a detailed description for now but is that the direction you were looking to go?
 
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Thanks Micilin,

Yes, that's exactly the direction I'd like to go.

I wouldn't be opposed to polystyrene with a fleck texture only I haven't found many websites which sell them in the UK and the ones which are about seem to be expensive.

When you say to form quoins with timber I assume you mean to screw battens to the wall to form a frame into which I apply the sand, lime opc, sbr mix? (I've seen some examples which look as though the quoins themselves are made of wood.)

Should I apply a mesh into the wall for the scratch coat to key into?
I've seen some videos only where they cover the wall with wood, tak on a mesh like chicken wire and then apply the scratch coat to that. Would you recommend that or should I just go ahead apply the scratch coat to to the concrete block wall?

Good tip about the curtain rails!
 
You would not need a special mix for the quoins, just for some kinds of mouldings .

Apply to blocks directly, or onto a scratched first coat. Set up battens onto scratch coat using masonry nails.
You can 'nib out' the quoins first and then remove the battens next day , using the hard render edge as a profile while you final coat everything together.

Or do the quoins first,then after a day , remove the battens ,then render the main wall second - so that nail holes are not seen in finished coat.

Hard to explain fully, maybe Have a look on youtube or on here for more and get back
 
Decopierre
Stone-Coat
Stonefxwalls
Imipierre
serach these for examples

try you toob for lots of samples.

Saw a shed done as random stone there somewhere and a polystyrene obylisk (is that how you spell that????)
 

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