Brisbane Build

[UtahBeehiver]

It is cheap insurance to vent the oven at the apex of the dome. Any water that sublimates from liquid to vapor increases in volume by a factor of 1500 plus which has the potential of building pressure under the stucco to the point of possible cracking. There are many solutions to vent the oven. Gulf and I used a breather vent found at any car part store for under $10. It is a 1/2" MPT where you use 1/2" PVC bushing seated in the vcrete and or stucco. David S has his built in the chimney stack..

[david s]

So, now ready to add a 50mm layer of cement render over the top of my rockwool.

Question though what mix have people used for their render?

At this stage I am thinking of using a sand, cement, lime mixture with the ratio of 6:1:1 Apparently the lime gives the render some elastic properties and reduces cracking ( found this on a rendering website). What do people think?

Also, have been reading about "vent holes" for the water vapor. Am interested to see what people have done and if they are really necessary.

The finish line is getting closer !!!!

A 6:1:1 mix is pretty lean, I prefer a 4:1:1. If doing a few layers each subsequent layer is meant to be slightly weaker. This takes way too much time for me and I do a 10-12mm layer in one go, but add plenty of AR glass fibres for reinforcing.
I think you will have trouble working over the rock wool. The more usual method is to do a layer of 10:1 vermicrete which provides a firm substrate to render against.

[NCMan]

I suspect that you will get compression to some degree with either product. I am using a product that WFO manufacturer suggested.

If you look at UtahBeehiver build , there is a debate in his thread about the layering of the dome and when to use the blanket. When reading through the thread and doing some research, it seemed to make sense to me use teh blanket over the top of the vermiculite and then have the render on top of the blanket.

My WFO will not have a separate housing as is seen in many builds in colder climates.

It wasn't about what layer, when. My comment was more about if you used rockwool instead of a ceramic blanket (?) Just wondering?

[Hatzi]

It wasn't about what layer, when. My comment was more about if you used rockwool instead of a ceramic blanket (?) Just wondering?

NCMan Sorry, misunderstood.

I am using Eco-Soluble Blanket D.128, 7200x610x25mm

It is a ceramic blanket see link below.

[Hatzi]

A 6:1:1 mix is pretty lean, I prefer a 4:1:1. If doing a few layers each subsequent layer is meant to be slightly weaker. This takes way too much time for me and I do a 10-12mm layer in one go, but add plenty of AR glass fibres for reinforcing.
I think you will have trouble working over the rock wool. The more usual method is to do a layer of 10:1 vermicrete which provides a firm substrate to render against.

thanks david s
have been doing a search for the last little while trying to locate where to purchase AR fibre glass - but unfortunately have had no success. If you are Australia based - can you direct me to some possible suppliers.

Also when you say "plenty" what does this mean?
Would the render layer work without the fibre glass.

[Hatzi]

oasiscdm did you use AR fibre glass in your render?

[oasiscdm]

Hi hatzi

No i used 2 layers about 25mm each, each with chicken wire to reinforce made top third 75mm layer.

I used QuckCote light weight render. Render was applied over the ceramic blanket.

Cheers

[david s]

thanks david s
have been doing a search for the last little while trying to locate where to purchase AR fibre glass - but unfortunately have had no success. If you are Australia based - can you direct me to some possible suppliers.

Also when you say "plenty" what does this mean?
Would the render layer work without the fibre glass.

I get mine from Domcrete in Sydney. Be a bit careful if you get them from Ebay you may get a better price but as they're coated with zirconium (expensive) which gives them the protection against alkaline attack, I've heard some manufacturers from China provide AR fibres with only a tiny bit of zirconium, just enough to qualify them as zirconium coated but they may fail.

For every 10 litres of dry render mix I'd add around one litre of fibres. The render layer will work without the fibres, but far better with them. I have used chicken wire instead of the fibres but because the dome is a compound curve it is difficult to apply. I found the best way was to cut strips about 30cm long and insert them as you go making sure it's in the centre of your layer. The fibres are more expensive but save a lot of time and far better to work with.

[Hatzi]

I get mine from Domcrete in Sydney. Be a bit careful if you get them from Ebay you may get a better price but as they're coated with zirconium (expensive) which gives them the protection against alkaline attack, I've heard some manufacturers from China provide AR fibres with only a tiny bit of zirconium, just enough to qualify them as zirconium coated and they may fail.

For every 10 litres of dry render mix I'd add around one litre of fibres.

once again thank you!

[Hatzi]

Hi hatzi

No i used 2 layers about 25mm each, each with chicken wire to reinforce made top third 75mm layer.

I used QuckCote light weight render. Render was applied over the ceramic blanket.

Cheers

Once again thank you!

[Hatzi]

Ceramic blanket has been added over the top of the perlite layer ( as per oasiscdm build) and as discussed previously.

Added chicken wire to hold everything in place. I must say that this part (working with the chicken wire) has been the most frustrating and unpleasant part of the build for me. It just did not do what I wanted it to do.

[Hatzi]

Today's effort.
Cut out (well actually grinded - why I am wearing a mask) bricks so as they can "receive" the chimney flue, which FINALLY arrived from dad. Needed son to come out and give me hand to hold things in place. Added bricks for the flue - waiting for mortar to dry before I neaten things up a bit.

Finally bit the bullet and started my first layer of render.

Rendering brick walls can not be that hard surely!!! Decided to try out my brick wall rendering skills - Came up alright if i say so myself. The real test will be when the wife sees it

Back to work in 2 days - so back to only really being able to work on oven on the weekends - and that is only when not running around with kids sport. So next weekend, nothing will get done as we are at futsal tournament all weekend.

[Delta]

Hi Hatzi,
Just found the AR Fibres at “Lyndons” who have several stores in Brisbane. A bag cost me $25 and it is enough to do 1 cubic meter.
Cheers

[david s]

Hi Hatzi,
Just found the AR Fibres at “Lyndons” who have several stores in Brisbane. A bag cost me $25 and it is enough to do 1 cubic meter.
Cheers

Something's not right there. A cubic metre is 1000 litres. You either got your fibres really cheap, someone's slipped a decimal point, or they've advised way to lean an addition.
How heavy is the $25 bag of fibres?

[Hatzi]

Hi Hatzi,
Just found the AR Fibres at “Lyndons” who have several stores in Brisbane. A bag cost me $25 and it is enough to do 1 cubic meter.
Cheers

that pricing sounds great!!