Building with stone & earth: Part II
Practical Action
taller structures.
For your foundation layer, you will need enough stones that are even longer than 30cm, so
that the foundation layer is wider than the wall itself.
Marking Out
For a round rondavel, you will need at this stage a central pole but for a square rondavel you
will only need the four long outside poles described earlier, not the inner pegs, when you
build a 'single' wall.
Let us assume that you are building a round rondavel, and that you have carefully placed a
straight pole in the centre. Mark out the size of the building on the ground as described in
the previous article, using a string and peg, except that you will only need to mark one circle
on the ground, not two. This circle will mark the outside of the foundation course. Next lay a
single layer of large stones, 35-40cm long, as the foundation course. Each stone is placed
against the rim of the circle you have drawn on the ground, with the stone inside the circle.
Ensure that they are all touching each other and are pinned securely so that there is no
movement when they are tested by being walked on. If any of the stones do move, secure
them by putting small wedge-shaped pieces of stone underneath, until the foundation stone
is stable After this, tie a marker knot in the string about 4 to 6cm in from the outside of the
foundation circle to guide you as you build.
Place a thin layer of mud
on an area of the
foundation stones and
place building stones on
the mud one by one,
breaking the joints by
placing each stone so that
it covers a joint of the
stones in the layer below.
Use the guide knot on the
string to measure the
outside face of the stones
only. The stones will each
be a slightly different
length, so the outside will
have a smooth face, and
the face on the inside of
the rondavel will be slightly
Figure 5: Only one circle is needed for a single skin wall
irregular. (You can always
plaster the inside afterwards if you wish.) Remember to use only enough mud to sit the stones
securely. Do not use thick layers. If part of the stone you are laying touches through the mud
onto the stone below, so much the better.
When you come to the doorway, try to alternate long stones with shorter ones, so that the door
opening is tied well into the wall.
You can build this type of building in only three or four days if you have the right materials.
But you do not often get something for nothing, and a fast building time is usually balanced
by the extra time it takes to find the right type of stones. On the other hand, you will need
much less stone overall for a single skin wall than for a double.
Finishing the wall
How you finish your wall when it is built is entirely up to you. Some people like to plaster the
inside to make sure there are no places for insects to hide, although if you have brushed the
joints smooth, this should not be necessary. Others like to plaster both sides. This can be
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