Advice on Stucco please

[kallipigous]

I've finished the insulation and started wrapping the chicken wire around my 36" Pompeii dome. I was hoping for some advice from those who have stuccoed their domes directly on the insulation.

I've never used stucco but from the various videos I've seen online I'm getting the gist of it. I'm expecting to do three coats: a scratch a brown and finally a covering layer. My question is though what to do about the inevitable creases and unevenness in the insulation. Is the idea to get the stucco to cling to the wire shell and leave air gaps underneath or to try and fill the gaps underneath with stucco? This will mean some areas have stucco that's much thicker but maybe that makes it stronger?

Thanks in advance.

Toby

[gastagg]

Have any pics on your wire mesh/insulation? I'm doing the same thing and looks like you're about a week ahead of me.

[Gulf]

I'm really not a fan of applying stucco to chicken wire over a curved surface. To me, 1" is a big hole to fill with stucco. I used 1/2" mesh construction cloth. But, that is not a big problem if there is a little backing behind it. However, I wouldn't fill those very deep voids with stucco. That will not increase the strength. I would fill any deep voids with insulation. Fiberglass insulation is ok outside of the ceramic fiber layer. It is not combustible and it is plenty far enough away from any "real heat" to melt. You can stuff those crevices after the wire is in place since you are using chicken wire. What you are trying to accomplish is to suspend the wire in the middle of a 3/8" to 1/2" scratch coat. Don't sweat it, though. It ain't going to be perfect on a compound curve. On the first coat, there will be some exposed wire. There will also be some holes. You can do the typical three coats or a hundred to get the job done. The three coat system is designed for speed. No one picks up that kind of speed from watching a video. My advice is to use a concrete bonding agent between each coat and forget about the scratching. After each coat, you can knock down the high spots and fill in the low spots with a damp sponge.

For applying each layer, I used a 12" or 14" sheet rock taping knife. They are built with a curve that helps with the application. Start at the bottom near the chimney and work your way around to the other side. Go back to where you started and over lap about half of the previous row. Repeat, until you reach the apex of the dome.






I hope this helps .

[kallipigous]

Ok thanks. I guess if I double the chicken wire it will give me smaller holes and make a stronger mesh to bind to? I am slowly filling in the holes as best I can but where the insulation overlaps it is thicker and there are creases. It's just impossible to make the insulation perfectly flat. I'm trying to avoid pinning the wire to the insulation as that shortcuts the insulation. If there are occasional holes underneath the wire and stucco I guess that's just extra insulation?

[kallipigous]

Here's an example. Small creases under the wire.

[Gulf]

Ok thanks. I guess if I double the chicken wire it will give me smaller holes and make a stronger mesh to bind to? I am slowly filling in the holes as best I can but where the insulation overlaps it is thicker and there are creases. It's just impossible to make the insulation perfectly flat. I'm trying to avoid pinning the wire to the insulation as that shortcuts the insulation. If there are occasional holes underneath the wire and stucco I guess that's just extra insulation?

If there are "air spaces" underneath the wire, that is insulation too .

[Gulf]

From that pic, I don't see a problem. You will be just fine .

[kallipigous]

ok great so I'll concentrate on the wire and not worry about filling underneath and if I get air gaps then that's all the better.

[kallipigous]

Any advice on sealing the duravent chimney stucco join?

[william]

Hi
I used a flat trowel to apply the stucco, The thing I learned was to make sure you have enough material for your first coat, you have some time to work the material, the dome shape is not that difficult. after the first coat I still had some areas that the lath was at the surface but with the second coat you have a firm base to build on. just try and keep the thickness of your second coat consistant. your final coat will be even easier
Hope that helps
Bill

[Gulf]

Any advice on sealing the duravent chimney stucco join?

That's above my pay grade, but I've seen some fab a ss flange, directly above that joint, to shed water. I think that David S. has done this on several of his builds.

[kallipigous]

I found a 6" flange that duravent sell so I'll try that and use some silicon.

[UtahBeehiver]

K,

I am not sure if this will help, but here are some pics of Metabestos flange similar to the Duravent flange you talked about. The flange was connected to the brick with concrete expansion bolts with a beads of high temp caulk under the plate, then capped with another layer of fire brick. Once the SS chimney was screwed on the flange I grouted the gap between the brick and chimney. It is going on 3-4 years no with no issues of the grout cracking. The double wall chimney keeps the temperature in the outer skin in check. Note the middle pic is looking at the bottom side.

[gastagg]

I've got the exact application and am using metalbestos chimney and have that exact flange. That's a great solution. When you say "grout," do you mean real grout? Probably a dumb question. Anyway, this will lead to an improved chimney for my build.

[UtahBeehiver]

Just some homebrew mortar.