Dry distillation of wood can produce stockholm tar and charcoal. Pine works best.

Dry distillation is performed by heating wood in a kiln (a thermally insulated chamber, like
an oven) with a flue (a chimney). The stockholm tar is condensated in the flue and recovered. The
charcoal stays in the kiln. Usually the flue is made from metal, as brick flues won't work because
 "their conductivity is too low to permit the tar to condense in any significant amount." [1]

***I am unsure though about clay***

The stockholm tar can be placed, hot, on wood, and sand/gravel added on top, to prevent the
it cracking in the sun. This provides waterproofing for shelters.

The charcoal can be used for firing metals in metal casting.

[1] http://www.fao.org/docrep/x5328e/x5328e0d.htm