Final Finish - Stucco and Chicken Wire

[JamesLynn]

Hello All,

Having completed my oven several years back my wife has decided that I really should complete it 100%. (lol). I initially insulated my oven with a 4/5" layer of Vermiculite/Cement Fondu. However after about six months of use I started to get cracks and heat leakage in the insulating layer. It's not a huge issue as the oven continues to function brilliantly. The only problem is that I can't really Stucco over the vermiculite as it will not withstand the heat leaks.

To address the issue I've decided to add a layer of insulating blanket and then the stucco finish.

My question relates to securing the chicken wire over the Stucco. What have others done to keep the chicken wire in place before you apply the stucco. While chicken wire is flexible, I am going to have to secure it down somehow. How have people been doing that? The oven doesn't exactly have hooks on it! I have seen lots of pictures but can't see what they have done to secure the chicken wire in place.

I saw one post that said not to worry about the chicken wire, but I think that's just asking for trouble as you need something to hold the stucco together in case of cracks. :

[david s]

Re: Final Finish - Stucco and Chicken Wire

I gave up using chicken wire ages ago.It is difficult to wrap around the compound curve. I now only use reinforcing fibres.

[Les]

Re: Final Finish - Stucco and Chicken Wire

To address the issue I've decided to add a layer of insulating blanket and then the stucco finish.

My question relates to securing the chicken wire over the Stucco.:

This seems to contradict. If you are adding the blanket, just wrap it around your existing dome and secure it with bailing wire. You should try and get the chicken wire in the middle of your stucco coat. To do that I used re-bar to make the form. In your case, I would simply use pieces of brick to achieve the desired spacing between blanket and wire. Does this make sense?

Les...

[JamesLynn]

Re: Final Finish - Stucco and Chicken Wire

Thanks Les, David,

Les, Makes perfect sense. Same practice as concrete reo.

David, S, what are reinforcing fibres? I am familiar with the various concrete fibre reo techniques.... is this what you are refering to? Glass and Plastics Fibres that you add to to mixture before application? If it is, given the thickness of a typical stucco coat do you get issues with the fibres sticking out. I don't what the oven looking it needs a shave...lol.

Regards and thanks
James

[david s]

Re: Final Finish - Stucco and Chicken Wire

I use two types of plastic fibres. some really fine ones and the other are course. The temp never gets anywhere near hot enough to weaken or melt them, but yes on a thin layer the odd course one does poke out occasionally, but you just pull it out and put it somewhere else. another way to do the chicken wire that works quite well is t cut small pieces about 6"x 10" approx. and place them, overlapped in the layer as you go.

[JamesLynn]

Re: Final Finish - Stucco and Chicken Wire

Thanks David, Being a local Aussie like myself, do you have any recommendation for the coating itself. I can mix my own render or go with a ready mixed commercial product. Any recommendations? I have a bit of experience with mixing my own mortars, concretes, etc and that's the way I am leaning currently. I see lots of references to commercial products but many are not available in Australia.

Cheers
James

[brickie in oz]

Re: Final Finish - Stucco and Chicken Wire

I would use sand and cement for render myself, you seem familiar with it so go for it.
The so called acrylic renders are just a cheap fix for the volume builders, cheap and nasty, its nothing more than thick acrylic paint with some sand in it for texture.

The traditional sand and cement render has stood the test of time which I doubt the acrylic render will do.

If mixing sand cement render make sure you get washed sand as sand with too much clay in it just doesnt cut it.

[JamesLynn]

Re: Final Finish - Stucco and Chicken Wire

Thanks Brickie, Problem solved. I'll go with my own render mix!

[brickie in oz]

Re: Final Finish - Stucco and Chicken Wire

If you use white sand, and white cement you can add any colour oxide you like to colour it too.

[david s]

Re: Final Finish - Stucco and Chicken Wire

Do a search on renders to help you. I use 4:1:1 silica sand, cement, lime. The addition of lime in the mix makes the brew stickier, which is great to apply, but more importantly for our application, gives it some elasticity. The downside is that the lime makes the mix slower to harden. Be sure to cover it well for at least a week to retain moisture while the hydration process is going on.

[brickie in oz]

Re: Final Finish - Stucco and Chicken Wire

No one in the trade covers it for a week, yet they have no problems.

[david s]

Re: Final Finish - Stucco and Chicken Wire

In the trade of cement rendering of houses this may be true, it is impractical to do so, it's very difficult to wrap a whole house. Render should not be applied in full sun or on windy days, this is another one that the builders ignore. In the trade of oven building or ferrocement it is mandatory if you want the end product to turn out with sufficient strength.

[brung99]

Re: Final Finish - Stucco and Chicken Wire

Hi David,

What are youre thoughts of adding a bonding agent like bondcrete/cemcrete to the render mix ?

[david s]

Re: Final Finish - Stucco and Chicken Wire

Hi David,

What are youre thoughts of adding a bonding agent like bondcrete/cemcrete to the render mix ?

Yes, you could try that in an effort to make the render waterproof. Personally I prefer to make sure the thing is 100% dry by doing about 10 cooking firings and then waterproof the surface. You don't want to lock moisture in the oven when it is still moist.

[brung99]

Re: Final Finish - Stucco and Chicken Wire

Thanks for your quick reply David. I'm rendering my dome tomorrow and am hoping I mix it correctly and it doesnt end up cracking on me, I thought the bondcrete would make it stronger and hold together better. I have some reinforcement fibres so I might go down that path instead.