Economic earth construction designed by Ray Meeker
The structure was built with mud blocks and
mortar, stuffed with ceramic products, and fired. The house itself
would get fired as a consequence. The fuel required for firing would
be largely accountable to the products inside. Mud mortar joints
would be made possible as they strengthen after firing. And further
economy would result.
Ray Meeker's technique offered the possibility of a moderate-cost,
yet strong house. Environmentally sound; climatically appropriate.
Pucca, yet made of the very basic elements - earth, water and fire.
The simple requirements were accommodated in
an equally simple plan - a central dome surrounded by four vaults
covering a 700 sq.ft area. There were only two main additions after
firing - the entrance canopy as a fifth vault in fired brick and
lime mortar, and a partial loft within the highest of the four vaults.
Nubian vault construction was followed for all five vaults.
The entire structure was sunken 75cm below the
surrounding ground level to reduce the buttressing necessary for
vault walls. The foundation walls were made of fired brick and lime
mortar with a damp-proof course administered in cement mortar. The
walls were constructed as composite walls - of fired brick on the
outside surface, and sunbaked earth bricks on the inside - but the
vaults and dome were made entirely with unfired bricks.
four arches supporting the Nubian vaults are constructed with the
help of a frame developed along a catenary curve. The vaults are
built without any centering - beginning with an inclined course
leaning on the base of the arch, and increasing the inclination
with each successive course until the desired gradient is reached.
For a vault 2m high with a 3m span, 10 courses were required to
reach the desired angle of 75 degrees, which was then carried through
the rest of the vault length. The frame for arch construction at
this stage served as a handy grid guide to maintain the catenary
Bricks touch one another on the interior along each course; their
gaps widening towards the exterior. Mud mortar, which shrinks by
as much as 35 percent while drying, can cause distortion of the
curve, cracking, and probably failure. In the Nubian vault no mortar
should be used between bricks of the same course, and bits of dry
brick should be tightly packed into the gaps.
The form, so simple from the architectural point-of-view,
was fairly complex from the point of view of firing as a kiln. Domes
and vaults in combination, and specially as the dome was surrounded
by four vaults, were a new experiment in firing, but successfully
fired in one operation.
A 10cm coat - 2 parts rice husk, 1 part cow dung and 1 part clay
- was applied over the dome and vaults. Initially the layer served
as insulation; later as an organic combustion layer. Hence in effect
the vaults and dome are virtually fired from two sides.
The stacking of products within is of prime
importance, as it determines the path of heat flow and therefore
how evenly the products and the building will be fired. The stacking
arrangement took about 4 weeks in this case. Some 60,000 table-moulded
bricks, 2,000 tiles, several gargoyles and terracotta toilet pans
were stacked inside the structure and fired for 4-1/2 consecutive
days with 23.5t for casuarina wood and 2,400 bundles of malaar.
The firing begun at the four vaults first involved the evaporation
of water from the vaults and walls and the products inside, for
2 days. The smoke was allowed to escape from holes high above on
Then the holes were closed and the heat directed
towards the dome, which was finished as a down-draft system, the
down-draft chimney placed in the centre and rising 2m above the
dome. After firing the temperature reached 900-900c at the thermocouple
points, but varied much more throughout the entire system - probably
800 degrees in the cold spots and 1,100 where the bricks began to
Once firing was over every opening was tightly sealed for 3 days,
after which the structure was opened.
The burnt tiles were used for flooring and part
of the brick in the external paving. Although the structure would
not slake in the rain waterproofing was essential as it was porous.
The water absorbed would significantly increase the load and result
It is necessary to have good brick clay on
or very near the site for cost-efficiency. Other architectural limitations
also exist, as the house must be primarily designed as a kiln. Other
than ensuring adequate draft, the interior spaces must be simple;
the roof vaulted or domed. The structural design is also limited
by the strength of unbaked earth; whether it will continue to stand
till fired. Above all the technique requires the expertise and supervision
of a specialist at every stage for scientific thermal applications,
demanding high precision.
The ideal economic situation
If good brick clay is available at the site,
materials and transportation costs are eliminated and transportation
costs are eliminated and labour is the only expense for the mud
brick construction. Further fuel efficiency can be realised by increasing
the length of the heat flow path as much as possible. If all fuel
and firing costs are justifiably borne by the products fired within,
the house will cost as much as one in unbaked mud and mud mortar.
With all the complex technological applications
involved, the overall appearance is one of simplicity. Agni-jata
is set sufficient with solar panels and a biogas plant. Ray Meeker
has been working on this technique since 1985, achieving more efficiency
with each successive experiment. He is presently engaged in a two-vault
structure at the Auroville Information Centre that promises to get
very close to the ideal economic situation.
Agni jata - Fire Born
This 30-minute video documents the
entire experiment described above. Contact: