Sunday, April 3, 2016

Maize storeage shed

We are almost done with this  building s for storing maize cereal after harvest until the price is right. Later it could be a car garage and outside storeage and maybe where chicks are kept.

The process.

Foundation was all stone.  Dry laid except last 30 cm, then a lime sand mortar.  On top of the stone was a 20 cm reinforced concrete beam, which  might  be overkill.

I overlapped the rammed sections.  Since then I have learned to not overlap and go straight up with no bond.  It is going to crack anyway 1/2 the time.
Note the  brick column around the garage door.  This made it easier I thought rather than cutting a board each time .  Also this way the ears of the door are set in the bricks instead of rammed earth.

The electrical boxes posed a problem as the ramming causes them to deform.  So you ram soil in the boxes before installing them.

The plastic water pipe for conduit does deform , because it is round?  my friend Roland says to take them all up instead.

These came out nice .  although there is a slight issue you see in the middle.  Need the guys to be more aware of how it will bond on the edge, sweep the top of the previous one, wet it, make sure the cornors are packed good.

On the back wall is a small window where we used boards as end pieces for around the window.  Then a brace to keep it in place. Had some issues with poor quality here.

Note the damp proof course and the notched end pieces.  The bricks below was formwork for the beam.

I used neighborhood boys who are unskilled and untrained.  They made a few mistakes but are catching on.  The need to check and recheck plumb.

Where do i get the soil?  From the trenches of the foundations and from an area I want to build another house with basement.  I learned to keep it covered so to control moisture in the mix.  It is best drier as opposed to wetter.

Reaching lintel height and I start cantilevering bricks to make eaves and form work for a ring beam for the vault to spring off of.  This was done by skilled mason.

 Reclaimed door frame, with arch over it.

 You can see the brick work for ring beam.

The wall came out reasonably well.

Inside showing the wall, arches and the ringbeam brick formwork

 At the door way i put in wedges so the corners don't break.  I should of done at corners also.
 Vault time.
-tie rods as the room is 8 meters long.  Don't weld bolts on the end of rebar, but rather have them threaded.
-strings to keep shape.

 always pleasant to look at masonry ceilings, or?

Real scaffolding

Timbrel?  Not really.  As this is a very flat arched vault the individual vaults can "pop".  The layer above serves to stop the popping.  It also makes the roof more rigid and stronger, however increases the weight and hence thrust on the walls.  Okay it is timbrel.

On top of the second layer a clay sand plaster to make it smooth to put a plastic vapor barrier.

On the short ends we needed a overhang of the walls, and we tried to cantilever the vaults but it didn't work.  kept popping off.  this wall will get some driving rain but the rammed earth should be able to withstand and dry off between rains.

Some aluminum tubes lined with tinfoil for extra light.

Soome trials with aluminum tubes with bottles on the outside in the roof.  this is with flash and there was dust or insects flying around.

 Same picture withoug flash.

the bottle light in the roof during day time.

the reclaimed metal door need some reclaimed wood.  Old Pallets and particle board from crates.

What i need to avoid.  there is some splashing on the ground from the eaves here splashing back on the wall.  dissappears in the day from a night rain.
 On the long walls the eaves overhang about 22 cm.  I dont see a problem.  The above problem will be remedied by some gravel.

What remains is the rammed earth floor and the roof.  Both are challenges.


We dug out all the top soil about 50cm.  then i filled with what we call mouram.  It is volcanic gravel, very corse.  this is vapor barrier.  It will not wick water.  then a layer of  broken bricks for a flat  platform for rammed earth.  So it doesnt dissappear into the gravel.  This is the first try with rammed earth floor and this is the first layer.  10cm of clay/sand and 8% lime.

You should let the first course dry before the smooth slurry but i wanted to try a test ares.  this is 1:1 clay soil and sand.  it takes forever to dry.
 Here i tried smoothing the rammed earth, it is possible to get smooth.

The roof i was originally was thinking living sod roof.  I am worried about the weight and roots going through weak plastic.  Then i did a test of rammed earth painted with lime wash.  I realise that will not work as it gets wet and dries repeatedly.  I think clay is out.  Then i thought of just covering the plastic on the roof with mouram light gravel.  Simply to protect the plastic from sun.  I might try that.  I also might try some sod along the bottom.

As i am playing with clay, next building i might have roofing tiles.


  1. The roof is definately Timbrel with 2 layers. It just also solves your poping apart problem, too.

    So what happens in the grain market to make it worthwhile to store grain? How much does the price rise in the months after harvest?

    And what part of Tanzania are you in? I spent a few weeks west of Babati about 10 years ago. Awesome landscape, it seemed to be how Texas was 150 years ago.

    1. After harvest most small growers want to sell immediately, so it is buyers market as there is more than the demand. As time goes on the price rises to twice sometimes three times the harvest price.

      where specifically west of Babati. We live in Arusha. 6km from center of town on what used to be farmland and is now suburbia. We own 4 acres .
      yeah sometimes parts remind we of wyoming. I have lived here 40 years. since i was 21

    2. Ah Arusha. Coffee growing area, if I recall. I only passed thru it, didn't stay. I'm not really a fan of bigger cities. The character and soul of a people lies in small villages.

      Interesting on the grain price volitility. Sounds like an excellent opportunity for contango arbitrage. Buy it cheap, hold it in storage and sell it. Which is exactly what you are doing. It is happening in my industry, oil, where people are renting tankers and buying 200,000 barrels of cheap oil, storing it on the bet it may rise $5 to pay for the tanker and turn a profit.

      On a more philosophical note, I spent several hours going thru your blog last night. As a kindred spirit and engineer, I've also researched dry stacked rock walls, alternative building methods, etc. This morning, my first reaction was "Wow, this guy has done some great research and learning about these alternative building techniques... but what is he going to do with his knowledge?" Thus, I encourage you to knock out a short (or long) book of 'lessons learned' and put it out there to further the knowledge base.

      Great to see your projects, Keep it up! And I'll post a link in a few months of my shed with timbrel arch.

    3. On the philosophical note.
      Odd as I think about the knowledge base frequently and I worry it was for naught. More that I know what doesnt work. I have made some stupid mistakes but the process had value. But comments like yours help me to post more, which i did after your comment. Havent had a comment in awhile. Looking forward to your process. I have "met" similar kindred builders and they are very helpful.

  2. Yes grain speculation is very lucrative here and many do it.
    I see you have interests in GIS. I play a bit at work with it and use it as I am avid mtn biker. my email is erik rowberg at gmail com. no spaces.
    you havent said which village you were in out by babati

    1. Yes, my company used to offer GIS training of free GIS software (QGIS) in seminars. Then my other company got a large contract to geospatially correct oil and gas well locations. That took over the company resources.

      I also do a fair bit of biking with a folding bike. Converted it to an ebike, and now take long road trips. I was wondering about how well it would fair on Tanzanian roads given that the wheels are 20" not 26" and the roads were poor.

  3. Nice Erik, and so big, you used steel bars from wall to wall in order to control the thwart forces against the walls ?

    1. Yes used 16mm bars . threaded the ends. had left holes in ring beam.

  4. I wonder if the tie rods could be avoided by putting in buttresses?

    1. yes i could do buttreses, and did on the brick kiln. Some day i will build something without steel, but buttress take room and time. i would make the vault much steeper so that the thrust is not so horizontal

  5. We can learn much from old and regional building practices, like Vitruvius' Treatise where he discusses different soil and water. In Tampa Florida my house is terra cotta block walls, and tile roof, but over the years attempts at quicker processes like drywall, and concreting up the ventilation openings have caused the only real issues. (oh and the 11 foot replacement beam poured without steel!) Builders bulldoze any house less than 3000 SFn throwing heart pine in the dumpsters.

  6. Bonjour, je vois qu'on a presque le même parcours et la même réflexion sur la marche à suivre de notre construction, vous avez commencé avant moi, et je vais continuer à lire, je n'ai pas encore construit avec un étage, ce serait dans mes projets futur, encore merci du partage. André