Hello from Uganda

[dmun]

Re: Hello from Uganda

Lime makes your mortar more sticky. You can make a mortar entirely out of lime: Some UK builders have done this.

[Janine M. LeGrand]

Re: Hello from Uganda

Wow, fast reply Dmun! If the main thing lime does is just make it sticky, I'll save my money unless we have trouble getting the cement plastering to stick to the mud. I don't think that's a problem as some people coat their mud houses with cement.
Thanks,
Janine

[Archena]

Re: Hello from Uganda

Hi,

I'm about to run out the door so I'll answer in detail later but DON'T USE CEMENT AS RENDER! On adobe (which is basically the kind of brick you have) or cob it can cause failure. The cement lets water in but not out - does really nasty things that way. Lime is an excellent render as it lets the adobe/cob breathe and get dry when need be. In Uganda it would likely not fail as quickly as in the UK but it's still a very bad plan.

I'll get back to you soon - kitty must go see vet and human must get to drugstore!

[Janine M. LeGrand]

Re: Hello from Uganda

Hi Archnea,
Thanks for the warning! Learning new things here all the time. I have a while still before I get to the outer coating, but please send details when you can. I had never hear of lime being used except in mixing with cement (or in cooking maize)....

Eager to hear more,
Janine

[Archena]

Re: Hello from Uganda

Thinking about what's in Termite soil--termite dung??? Given the soil here maybe some human and other critter's nasty's too. Actually, it is the human pathogens that give me the willies--I'm here as a health advisor/coordinator for the Church of Uganda and I'm all too aware of contamination issues. I can't think of any termite-human zoonosis so that part is pretty safe. I'll just keep repeating to myself "It's sterilized, it's sterilized, the heat of a WFO sterilizes it--besides it's stuck in the clay" Plus there's always the pizza pans--believe it or not I bought some in Kampala!

Err, no. Actually termites are fairly fastidious little critters; termite poop goes into the termite trash heap. But they prefer their homes to be a little sturdier than their ant cousins do. Part of what makes termite mounds such good construction material is the chemical glue that the termites use. Basically, it’s held together by termite spit. Before you panic, it’s actually remarkably sterile. Like I said, termites are fastidious little devils.

And no, it won’t survive the heat.

:Cob or brick--good question. The deciding factor for me is do I have enough bricks on hand; I usually buy them by the truckload as I don't want to waste the transport cost. I think I have enough on hand for the oven if I use the half-bricks (broken bricks). So the plan will be to start with whole bricks and as I go up the dome and the circumference gets smaller I'll start using half-bricks. I'll use the termite soil with sand added as mortar. I think pieces of the brick are a little less likely to flake off as could happen with the mud given the surface cracking... Any flakes on the floor will get brushed off with the ashes, but don't want something dropping in my food. Hopefully after I've fired the oven that won't be a problem though. After the bricks, then I'll cover with termite soil-grass-sand adobe for insulating the dome. Lastly a coat of cement to waterproof.

Sounds like you got a plan. FYI, cob really doesn’t have a problem with spalling. Think about it, it’s basically brick fired in place. None of the people who’ve made cob ovens have had any trouble with it.

Do you know if I should get some lime to add to the cement? Last time I checked it was available. Does lime make cement more waterproof?

Dmun already handled that. I’m going to punt to him, and others who know more about concrete than I do.

:Archena, glad to here your friend is coming to Uganda--many people know almost nothing about this country. Check with him and see if he is coming near Masindi. Masindi is near a popular safari area called Murcheson Falls on the Nile River. You can see crocodiles, elephants, giraffes, lots of birds, baboons, etc. there. I know a group of Americans mostly from S. Carolina are coming in December with Palmetto Medical Initiative (a great group of people--you can check out palmettomedical.org if you're interested).

He'll be near a town called Bugiri, somewhere in the southeast near Kenya.

I flunked Ugandian geography so I'm clueless.

I will check that out.

:Oh, on puting up the pictures--I put some in the gallery at first, but I couldn't figure out how to get the link to them in the thread post. At least this way works for me, putting them in the post.

I actually prefer them in the post myself. But just so you know the way to do it is to create an album and link the album to the thread.

:Thanks for all the advice and encouragement.

:P.S. I love the the Jim Elliot quote

---Janine

You’re more than welcome. Maybe some of it will be even useful!

Thanks, it’s my all time favorite.

[Archena]

Re: Hello from Uganda

Hi Archnea,
Thanks for the warning! Learning new things here all the time. I have a while still before I get to the outer coating, but please send details when you can. I had never hear of lime being used except in mixing with cement (or in cooking maize)....

Eager to hear more,
Janine

I'm attaching a link from a guy who builds and repairs cob houses. The long and the short of it is concrete has a tendency to crack, because it doesn't expand and contract at the same rate as the adobe/cob. Those cracks let in water, but the water has no way out. Bad things result.

Lime? In maize? I've heard of lye being used to make hominy/grits but how do you use lime?

East Devon Traditional Cob Building Specialist, New Houses and Repairs - Kevin McCabe

[ThisOldGarageNJ]

Re: Hello from Uganda

Hi Janine,,
How is the oven progressing ??

Mark

[Janine M. LeGrand]

Re: Hello from Uganda

Hi folks,
Sorry I have been so quiet for a while; I had some major computer difficulties which kept me off-line. Getting problems like that fixed is a bit more of a challenge in rural Africa but I am back now.

The oven is not quite finished but I am using it--the interior goes white and I have been getting some awesome food! I have to admit that I didn't really believe when people said that everything tastes better coming out a WFO, but so far it is true! I have done onion flatbread (first cooking attempt--the oven was a little cool and still drying the adobe but tasted good). Since I have made a number of pizza, a beer-can chicken YUM, and pork ribs plus grilled veggies and roasted garlic. I'm really eating well!

The oven has a few cracks, as expected but is holding up great. The outside never gets more than barely warm even with 24 hours of firing. I do still have a pile of termite mud adobe already mixed and will put that on for a bit more insulation. I also need to make a simple roof -- we are entering into rainy season. For now I am keeping the oven under a tarp if not in use--lost a few mm of adobe when a storm came as I was firing but as I said we will be putting on more adobe anyways.

Thanks so much for all the help--I have a working oven!!! (Will have a pizza party tonight) Here pics:




Your guys are amazing--thanks for all the advice!

[ThisOldGarageNJ]

Re: Hello from Uganda

congratulations on finishing,, I think its a very cool looking oven,,Is the whole community using it ? Nice job janine

[Archena]

Re: Hello from Uganda

Totally cool! Looks great! Congratulations!!!


FYI: We had another lady (whose name escapes me or I'd link the thread) who tried the 'tarp over mud/adobe/cob' thing and had a huge bug problem as a result. Without the tarp the critters stayed away but the tarp allowed humidity to build up under it and get trapped creating a perfect little micro-habitat for our eight legged little enemies (y'all can call 'em friends if you want to). Moral of the story is that it's probably better to only use a tarp when it's raining and get that roof built ASAP.


So, how did you build it? You hadn't completely decided on a few things as I recall. Come on, inquiring minds want to know!

Wood fired oven fans can be a bit obsessive, huh?

[Archena]

Re: Hello from Uganda

<begin off topic, trivial rant here>

Why does the image limit include smilies?


<insert angry ranting smilie here> Stupid image limits....


<grumble>
</end off topic, trivial rant>

[Frances]

Re: Hello from Uganda

Very cool oven! Looks great, well done!

[texassourdough]

Re: Hello from Uganda

Hooray!

Great to hear you are back online and eating well!

Bravo!
Jay

[Janine M. LeGrand]

Re: Hello from Uganda

How did we build it? Details? Ok, I'll try to recap. Please ask if I don't cover something you want to know...

Starting off, we put down about 2 to 3 inches of "insulation" made of termite mud, clay and lots of short cut pieces of grass stems. Then a layer of local bricks to make the oven floor. We covered the floor bricks with several thin layers of termite mud and clay in order to get a smooth floor--the bricks were very uneven in size so this was needed. Then we let that dry a few days.


We built up a big dome of wet sand, packing it down as we went. Actually we were running out of sand, so we also threw in broken brick bits as inner filler in the center top. We made sure the brick pieces were large enough to easily sort out from the sand as after its use as an oven form the sand will go into concrete for another building project. I scribed an opening for the entry arch and let the sand sit overnight.

We made the oven walls out of local brick motored together with termite mud and sand and followed the shape of the sand form. Is it called cambering in?? We didn't keep the bricks horizontal but tilted them following the curve of the sand. I avoided bricking in the area's for the archway/doorway and the chimney.


I made a simple wooden door out of wood we had used for a frame pouring the foundation. I chose the shape of the door by making a temporary arch out of brick flat on the ground. I used the door itself as the frame for building the arch as we built it vertically in place.

The joining of the entry arch (which is flat) to the curved walls was a bit of a challenge. After the entry arch was at least a little bit dry, we put the door in place and braced the arch itself. Then I filled in the odd-shaped space between the dome and the arch with wet sand. Then I made the walls with the connection holding the mud up by resting it on the added sand.

The last layer was a homemade adobe--termite soil + sand + lots of hay-like stems of grass. We covered the sides and top of oven to insulate. We have enough now mixed termite adobe that I will put on another layer when I can bear to stop using the oven.

I fired the oven with a series of fires, starting small and ending up with a big burn. I kept a good fire going for over 24 hours to help to dry out the adobe and that seemed to work.

Then next was lots of cooking--in fact now I just finished munching on homemade WFO bread and WFO roasted garlic.

I have had a few problems with rain. If rain threatens, we put a tarp over the oven. If the oven is hot and rains come I just keep a big fire in it to help drive out the moisture. Thanks, by the way, for the warning about keeping an adobe over covered with a tarp....for right now it is being uses to much to get bugs--it barely cools before I fire it again. Snakes might like the warmth, but I have the oven itself off the ground. I am planning to build a simple roof out of local poles and some iron sheets.

Hope I answered most of the questions--I am getty very tired now as it has been a very long day (I was up most of last night). Ask whatever else you want.

Yours in Christ,
Janine

[cynon767]

Re: Hello from Uganda

I just have to ask- does that chimney lead directly into the top of the oven chamber? If so, you might want to consider bricking it in and just letting the smoke out the front. Having a vent at the top of the oven that way will let out a tremendous amount of wasted heat. Hot air rises, and it will just go straight out a top vent before it has a chance to really heat the brick to its full potential. The door may still be a little on the tall side, but that's not as easy a fix, and may not be quite as important.

Otherwise, it looks pretty fantastic. Good work!