Render/stucco dome a little help needed

[david s]

Re: Render/stucco dome a little help needed

Don't be in a rush to render over the vermicrete. If you calculate the volume of vermiculite used then you have added approximately a third of that volume in water. As you have made quite a rich mixture 8:1 verm. cement, then the mixture will not dry quickly because more of the spaces between the grains are filled with cement. Suggest you fire about 10 times before considering rendering over it otherwise you risk cracking the outer shell from steam expansion. Also suggest waiting until the outside render is complete and hard and again well fired before waterproofing. The render mix I use is 4:1:1 sharp sand, cement, lime.
Good luck.

[eatingmorefood]

Re: Render/stucco dome a little help needed

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[chidding]

Re: Render/stucco dome a little help needed

Appreciate the help guys! this forum is the only reason i could do this project!

[OscarA]

Re: Render/stucco dome a little help needed

Anything one can add for elasticity?

I believe lime helps, my mortar mix was 1 part cement 1 part lime and 4 parts sand.

[chidding]

Re: Render/stucco dome a little help needed

You can use chicken wire. I find the smaller holed stuff better and get it on a roll (160 mm wide) you can then cut it into workable lengths and overlap it.

Yea ive got normal chicken wire but cut into strips!! just thought fibers would add extra strength..

Anything one can add for elasticity?

[david s]

Re: Render/stucco dome a little help needed

You can use chicken wire. I find the smaller holed stuff better and get it on a roll (160 mm wide) you can then cut it into workable lengths and overlap it.

[chidding]

Re: Render/stucco dome a little help needed

Sorry to thread hijack!

I'm looking to render my dome this weekend. I'm going for a
Limestone look. Would it be possible to use brickies lite cement plus normal yellow sand?

Is there something I can add to the mix to limit cracking? Like the above fibers? Or something else.

What would I seal with once completed?

[david s]

Re: Render/stucco dome a little help needed

Because the refractory is extremely porous, in wet weather it will suck up water from the atmosphere even though the oven is completely sealed. Water can often get in around the door and also around where the flue enters the outer shell. Also you tend not to use the oven in really rainy periods so its not getting dried out. I've found it does not seem to need to go right back to the original tiny curing fires, but if you haven't used the oven for ages after rain it is a good idea to give it at least one or two slow fires before really revving it up.

[cobblerdave]

Re: Render/stucco dome a little help needed

Dear Oscar
I believe you have it all covered......98 per cent is close enough

Regards dave

[OscarA]

Re: Render/stucco dome a little help needed

Hi Neil2

I am going to cover the dome with an acrylic sealer to help waterproof it as best I can. The acrylic layer will completely cover the dome and stand. Then I will lay down terracotta tiles on the stand and do a brick tile border (same tiles as the arch). When all done I will then cover the tiles, bricks and arch with a concrete sealer. So in short the dome will have an acrylic flexible sealer and the tiles, brick will have a concrete sealer.
I will never make it 100% waterproof I realise but water resistant it will be.
If down the track I find I'm having water issues then the whole thing will be inclosed but as I like the dome look I'm hoping that wont be necessary.

[Neil2]

Re: Render/stucco dome a little help needed

You may want to consider an acrylic stucco outer layer to improve "water resistance".

Note that you can never expect a stucco based outer shell to be 100% water proof.

[OscarA]

Re: Render/stucco dome a little help needed

Thanks David much appreciated.

[david s]

Re: Render/stucco dome a little help needed

Oscar ,
Sorry I didn't answer your last Q. Re render mix. I use 4:1:1 silica sand, Portland cement, lime mixed by volume.
Dave

[OscarA]

Re: Render/stucco dome a little help needed

Thanks David I'll do just that. I'm not sure how much Render will be needed to cover the oven but I'll do as you suggest and go back to Bunnings if more fibers are required. Better to play it safe.

[david s]

Re: Render/stucco dome a little help needed

Oscar,
I forgot to also mention that I use 50% more fibres than what they recommend. Make sure you mix it well (about twice as long as you would think) for full dispersion.