Eating is an agricultural act - Wendell Berry

Sunday, January 30, 2011

building our house - part 2 - brick making

a house should and can be built with one's own hands.
before the advent of congested cities and the resultant high-density-high-rise models of residences, people and societies have traditionally built their own homes with locally available material and labour.

even today, rural folk continue to abide by these ecologically sustainable and low environmental impact (and thus low cost) tenets on models of housing construction.

following such traditions, we are building our walls with the adobe brick maker....
this is not part of the adobe acrobat suite; this is a method of making simple, strong and unfired (aka sun-fired) bricks for house construction.

adobe is simply a mixture of soil and water and some straw/dung which is cast into cuboid shapes and dried in the sun.
this method saves cement (neither the mortar nor the plastering will use any cement).
it is a batch process, i.e., you can complete making the bricks fully prior to starting construction (as against cob walls which have to be made as the clay is being mixed).

we also contemplated rammed earth walls, but felt that we did not have the necessary experience to take it on (both cob and adobe bricks have been already used for the construction of the kitchen and bathroom). it goes.

of course we need tons of dirt/soil. so dig it up with the mini excavator.
this resultant hole in the ground could be a mini pond, foundation pit for another house, etc.

then comes the first of the exhausting acts. lugging this dirt to the mixing spot.

then piling it up. we made piles with around 30 containers of soil per pile (the one being loaded onto my head in the earlier pic).

then make crater-like holes on the pile and fill it up with water.

neat, isnt it?

then mix away. the second of the exhausting acts.
we have a video of this mixing process and will upload that separately.

add the chopped straw. this is the same concept as fibre reinforced plastic.

do the tribal dance. this step is super vital for the complete and effective mixing of the water into the clay.

the shovel mixing and dance mixing is done around 3-4 times to get the correct pastiness of the soil mixture.

this is the final mixture. our subsoil dirt was a bit gravelly and hence it looks grainy.

it is best to allow this mixture to remain overnight.
the wetness just spreads more and evenly.

the mixed soil is poured into these brick moulds.

dimensions of larger mould is 10" X 14" X 3.5"

first wet the mould and place on ground.

then act 3 of the exhausting trilogy. ferrying the mixture to the brick layers.
pack the mixture into the mould. tamp the edges well to get the smooth and straight edges.
use a scale/thin plank to even out the top.

straddle the mould and yank the mould (almost at once after filling) slowly while gently shaking it.

if your mixture is done well, the brick will retain its shape. also observe edges for smoothness to check the effectiveness of the tamping.

after 2 hours of brick laying, here is how our first batch looks.

in this weather, we were able to turn the brick (on their edge for quicker and comprehensive drying) within 48 hours and brick is fully dried and ready to use in 7 days (of decent sunny weather).

there is a strength test recommended - dropping a brick on its edge from 4 feet.

strong. barely chipped the edge

there is also a strength test which is not recommended.

total bricks needed ~1700
total containers of dirt ~2300
i.e., upwards of 23 tons of soil will need to be dug, ferried, mixed, laid, stacked and made into walls.


Arjun said...

great initative guys... btw, dont you use wheelbarrows?? 2300 headloads could kill you. :)

Anonymous said...


The bricks look perfect, and stronger than burnt ones (assuming the பயில்வான்s are not faking it!)

How did you get the correct clay/sand proportion?
How did the red soil become black after mixing?
What was the percentage of straw in the mixture?
Each brick from your data, is more than 10 kg. Is there a way to reduce weight without compromising the compressive strength?

Anonymous said...

Excellent initiative and project. Wish you Good Luck. Your experience will be helpful to many others.

Thanks for sharing.

csm said...

arjun - wheelbarrows are actually a pain, unless you operate it on a runway. we used it for transporting saplings in the past and killed our backs.

anon 1 - dv had earlier made adobe bricks and it just so happened that the gravelly sub-soil in the upper slopes out here offer a ready-made correct proportion.
check that picture again :-)
straw is approx 5-6 handfuls per 60 containers. cant calculate %...

the smaller bricks (smaller mould are just as strong). do check the links in wikipedia for the tech sheets and history and other such stuff.

anon 2 - thanks

Preeti Aghalayam aka kbpm said...

did your hands pass the taekwondo test?? :-)

csm said...

kenny - did not even try... realised how strong they were when we dropped them....

Rags said...

What about the foundation? With the rain that you guys had this year, the foundation better be strong & ontop of that these blocks can sit pretty.

csm said...

rags - if you read part 1 (design), you would have noticed that foundation is a separate part in this documentation giving you enough indication on how much thought it going into it...

Anonymous said...

In case if you get a time and willing to share, Please tell us which factor/s played a role to not to go for rammed earth option? Since one day I am thinking to build something by myself and considering pros and cons of the rammed earth. Your experience may be helpful to me.


Anonymous said...

Hi Babs,

Into real estate now, eh? Awesome... Guess you will be starting making your own clothes soon enough.. from the yarn up... ;)

Okay, I'm gonna hazard a guess on the cost of the house... I am guessing around 1 lac per house (300 sqft) - not including cost of labour... Let me know if I'm anywhere in the ballpark..

siddharth said...

this is exciting! will be really interesting to see the progress and your documentation on this. good luck!!

csm said...

anon - we are planning a smaller expt with rammed earth for our second toilet, before we take a decision on using it for larger constructions.
we have already made the formers and the sieves for that expt which will start soon.
so we are not (by any stretch of imagination) ruling out rammed earth construction here.
just that we chose adobe for this project.

shets - tu tho real estate ka baadshah hai miyan. aur woh bhi bambai mein.
you are resonably there ;-)

sid dada - agar tu hota, tho aasani se kar dete.

nisha said...

great show! double up on your carbs :)

sameersampat said...


Musings said...

Awesome!!! Really I appreciate your determination in making the house. More than physical strength, it is the mental strength that should be appreciated.

SurveySan said...

just curious, do you need to get any plan sanctions before putting up the structure from the VO or any government orgs?

looking forward to the frequent updates. sure is fun.

csm said...

thanks nisha, ss and musings.

ss - none needed. we would need if we are building it in the village.
we would also need something if we were building some resort type construction.
since we are not using any utilities, this permissions are not applicable.

madhavi said...

wow - nothing more to say - csm can we do it on a small scale ie smaller mold for children in school to learn - using red soil that you get at garden center, some sand and straw for science fair project and make a small house - mold can be empty matchboxes - any suggestions have no looked it up on the web just a thought.

Pushpraj said...

SKD brilliant stuff.. My Dad runs a Chamber near my native place (tiruturaipoondi). They have a wire cutting machine but previously used to do the mould system. They always fire the bricks (either country kiln or chamber).The soil quality must be critical as I guess not all soil will work..

csm said...

m - smaller moulds are possible. but not matchbox size :-)
the classic brick size would be ideal.

p - we knew the place which would give us the desired earth.
in many cases, some adjustments will be inevitable. but it is quite easy (to add sand, for eg) as we are anyway mixing things heavily.
also fired bricks are a must for modern type construction (concrete based multi-storey), while unfired will work only for ground+first.

Dominic said...

As house builders in Torquay, South Devon and The South West we really appreciate your construction blog.