36" Pompeii Dome - Thailand

[david s]

Yes, you’re correct. As you’ve already purged the inner oven of moisture it doesn’t matter how you get rid of the water in the vermicrete layer. Sun wind or fire, just get rid of it before rendering over it.

[danhem]

Got the v-crete layer complete. The first two rings were quite difficult, certainly time consuming making sure the material held up instead of crumbing off to a frustrating mess. The later layers were actually enjoyable as it feels like another step closer to completing the build. About to set a fire and will dry the vcrete out before the stucco layers.

I'm now researching the stucco layers and the oven vent as recommended in another post due to the wet and humid climate we are in for 6 months of the year. Came across this post by Gulf - Vent Planningand it looks like a pretty simple addition during the stucco layer. I had a wonder around the hardware store for ideas and settled on a pipe attachment. Not sure if the plastic material is ideal for the vent pipe but couldn't really anything else that would do the trick.

[UtahBeehiver]

Should be fine, the ones Gulf and I use are made from PVC.

[TxGR]

When we exchanged notes before, I didn't realize you had a thread. I feel badly about that now. Too late now, but I ordered lots of things from Amazon in the US (especially blades) and they arrived in Thailand no problem, even after everything was shutdown for the CCP virus. The bad part was the shipping costs were really high and sometimes the delivery folks look for any excuse to return it rather than make a residential delivery.

Your oven looks great. You've done far better than we did, especially starting with smaller fires.

I have zero control since I left in March, and no matter how much I tried to explain the construction process or the importance of firing up slowly over a couple of weeks, they just blazed ahead and did their own thing. I'm pretty sure I'll be rebuilding, at least partially, in a year or two.

What are you using for wood? Where are you sourcing your wood?

[danhem]

When we exchanged notes before, I didn't realize you had a thread. I feel badly about that now. Too late now, but I ordered lots of things from Amazon in the US (especially blades) and they arrived in Thailand no problem, even after everything was shutdown for the CCP virus. The bad part was the shipping costs were really high and sometimes the delivery folks look for any excuse to return it rather than make a residential delivery.

Your oven looks great. You've done far better than we did, especially starting with smaller fires.

I have zero control since I left in March, and no matter how much I tried to explain the construction process or the importance of firing up slowly over a couple of weeks, they just blazed ahead and did their own thing. I'm pretty sure I'll be rebuilding, at least partially, in a year or two.

What are you using for wood? Where are you sourcing your wood?

Hi,

No worries, it's been a tough but fun project, after I saw that you had stopped posting here I realised you were no longer here in TH. Actually the most frustrating part of the build has been sourcing the materials and navigating the weather, which has been particularly bad here in HH this year.

All in all I'm pretty happy with how the oven has turned out, DIY is not one of my greatest attributes but with the help of this forum and a careful approach to each step I'm managing to make some cracking pizzas. My only real concern at this stage is whether my oven is retaining enough heat - I'm not recording much heat loss during a fire but the internal bricks seem to cool down faster than others here have recorded (makes me wonder if the BST bricks are any good or if they are the same rubbish as their refractory mortar ), but patience in this respect has been suggested so I'll carry on with fires and complete the job ready for the dry and cooler season in November.

I feel for you on how your contractors have carelessly f***ed up what started as a very nice looking job. It might sound over dramatic but I'm sure it breaks your heart.

I responded to the wood supply in the other post, if you find anything better, please let me know.

Danny.

[danhem]

Yes, you’re correct. As you’ve already purged the inner oven of moisture it doesn’t matter how you get rid of the water in the vermicrete layer. Sun wind or fire, just get rid of it before rendering over it.

Hi David,

I'm now looking at getting the materials together for the rendering layers. Is there a best practice here? I'm unsure on whether to buy the render or to mix it with the remaining lime I have.

If going the home mixed route, is the a recipe to follow i.e. sand:limeortland etc? I see that other members have also added to nylon fibres to their mix to prevent cracking.

Hoping to get these final steps complete in the right manner so I can put the job to bed once and for all.

Many thanks.

Danny.

[david s]

Hi Danny,
most commercial renders have some waterproofing added which produces some resistance to water absorption at the same time as leaving it breathable. You can tell this by the difficulty in getting water to mix into the product initially. If you make your own mix it won’t have that property, but if you want to make it waterproof you can do that over the top later or leave it porous if it’s under a weatherproof roof.
4:1:1 sand, lime, cement is a pretty good mix and the lime imparts some elasticity as well as some crack self healing.
Random mixed fibres are a much easier way to reinforce the layer than chicken wire, but more expensive. The time saved in labour is well worth it IMO. You can use the nylon fibres, but I find the 19mm AR glass fibres better and easier to work with than the nylon ones which are longer thicker and stiffer. This means you have to pull them out every so often in a thin layer.

[danhem]

Hi Danny,
most commercial renders have some waterproofing added which produces some resistance to water absorption at the same time as leaving it breathable. You can tell this by the difficulty in getting water to mix into the product initially. If you make your own mix it won’t have that property, but if you want to make it waterproof you can do that over the top later or leave it porous if it’s under a weatherproof roof.
4:1:1 sand, lime, cement is a pretty good mix and the lime imparts some elasticity as well as some crack self healing.
Random mixed fibres are a much easier way to reinforce the layer than chicken wire, but more expensive. The time saved in labour is well worth it IMO. You can use the nylon fibres, but I find the 19mm AR glass fibres better and easier to work with than the nylon ones which are longer thicker and stiffer. This means you have to pull them out every so often in a thin layer.

Thanks David, I’ll go the commercially purchased route in that case.

Regarding the AR fibers - is this a necessary step? I was thinking to render directly over the vcrete layer but you have mentioned a lot reinforce the render layers?

AR fibers seem to come in 20kg bags here and as you mentioned are quite expensive. Do you have a rough idea of how much AR Fibre I would likely use?

[david s]

Yes, I get mine in 20kg bags and they’re not cheap. But it’s way faster than covering the dome in chicken wire. I used to cut the chicken wire into bits about 30 x20 cm and place them, overlapping as you go, rendering the outer shell. This may be a better method for you than going the random fibres route.

[danhem]

Yes, I get mine in 20kg bags and they’re not cheap. But it’s way faster than covering the dome in chicken wire. I used to cut the chicken wire into bits about 30 x20 cm and place them, overlapping as you go, rendering the outer shell. This may be a better method for you than going the random fibres route.

Thanks David, you’ve been a great help in these latter stages of my build.

I’ll bite the bullet and get the right tools for the job. Not sure how much of the fiber I’ll use but I guess I’ll find a use for it further down the line.

[danhem]

Things moving ahead nicely here, v-crete layers complete and dry, and materials finally in place to begin the rendering. I went with David S advice and purchased AR fibres, they took a while to arrive.

In the meantime I now have a door and have extended the chimney pipe. The door was custom made by a local metals works and was based on a cardboard prototype I made up. I have had to trim the top edge of the outer door as it was catching slightly on the arch bricks but apart from that the fit is very snug and the door will definitely serve its purpose. The design has been copied from many here on the forum - a cavity filled with ceramic fibre board. I'll fit some wooden handles at some point. I didn't have the energy to search and wait for a temp gauge online so skipped this part. It's a plain door but it insulates well and will be fine for my cooking needs.

The chimney - I made a pretty big error when ordered the chimney as it was way too short. Whilst the draw was pretty good, I have a building roof too close to the smoke outlet, which caused smoke to gather under the roof overhang and circulate around the oven area. Not so bad once the fire got going but not very nice. So I extended the pipe by 60cm and have very pleasantly surprised at how well the local steel guy has put it all together. The added section is the lower section of the chimney and fits perfectly over the existing anchor plate. Doubled walled SS, stuffed with vermiculite, and somehow welded to the original pipe. To cover the weld connection there is a SS ring around the joint. After one heavy fire the new 2meter chimney is sucking perfectly fine and discarding smoke much better. Very happy with both the door and chimney.

We have now employed a contractor to cover the oven, work surface and seating areas with a lovely wooded framed structure. The oven will be completely protected by the weather elements with a roof and the seating areas will enjoy shading from the sun. Pretty excited by the prospect of a completed project that will fast become the favorite and most used part of our house.

[danhem]

I’m looking to fit a small metal plate as decoration (with the year of build etched in) just above the outer arch. The space I want to use is part of the flue gallery brick formation and does get quite hot during a fire.

im initially thinking of using copper/brass for aesthetic purposes, mortared in place with home brew, but wonder whether the heat will cause the metal to expand and thereby crack the mortar?

[Mongo]

I’m looking to fit a small metal plate as decoration (with the year of build etched in) just above the outer arch. The space I want to use is part of the flue gallery brick formation and does get quite hot during a fire.

im initially thinking of using copper/brass for aesthetic purposes, mortared in place with home brew, but wonder whether the heat will cause the metal to expand and thereby crack the mortar?

I set some tile on my chimney and did some searching in the forum. Concluded that home brew is not the way to go. A 'flexible' construction adhesive or flexible mortar is the way to go.

Aparently a product called Monoflex is the material of choice. Available in Oz an NZ but not North America (good for you maybe).
I ended up using an 'elastic' adhesive specifically for masonry made by Quickcrete. Applied from a tube from a caulk gun.

Here's what the giant brain says about Monoflex: "A premium, water-resistant, flexible, rubber-based, fast-setting, cementitious adhesive for bonding ceramic and stone tiles to porous and non-porous surfaces subject to vibration and thermal movement."

A David S. post: https://community.fornobravo.com/for...723#post419723

[danhem]

I set some tile on my chimney and did some searching in the forum. Concluded that home brew is not the way to go. A 'flexible' construction adhesive or flexible mortar is the way to go.

Aparently a product called Monoflex is the material of choice. Available in Oz an NZ but not North America (good for you maybe).
I ended up using an 'elastic' adhesive specifically for masonry made by Quickcrete. Applied from a tube from a caulk gun.

Here's what the giant brain says about Monoflex: "A premium, water-resistant, flexible, rubber-based, fast-setting, cementitious adhesive for bonding ceramic and stone tiles to porous and non-porous surfaces subject to vibration and thermal movement."

A David S. post: https://community.fornobravo.com/for...723#post419723

Hi Mongo,

Thanks for this and apologies for not getting back to you. It does look like there is a similar product here in Thailand that will work as described by yourself and DavidS.

Thanks again.

[Vinz]

very pleasantly surprised at how well the local steel guy has put it all together. The added section is the lower section of the chimney and fits perfectly over the existing anchor plate. Doubled walled SS, stuffed with vermiculite, and somehow welded to the original pipe. To cover the weld connection there is a SS ring around the joint. After one heavy fire the new 2meter chimney is sucking perfectly fine and discarding smoke much better. Very happy with both the door and chimney.

Great idea to stuff the chimney walls with Vermiculite... didn't think of that and 'the cleaners' definitely threw away the remaining.. anyhow, the air in between insulates pretty well, but still the chimney sides is one of the hottest parts of the whole build.
I had a double walled, square base, stainless steel chimney welded. together with a curved mount that fits the arch the welder charged 3000THB. Plus a pizza.