Complex sentence: This is due to the birth of his son and because although the cost of living is rising his wages are not because of the decreasing demand for his profession at a time when metal tanks and motorized tankers are replacing traditional wooden barrels.
Split into simpler sentences: This is due to the birth of his son and the rising cost of living with which his wages do not keep up. His trade is in decreasing demand because metal tanks and motorized tankers are replacing traditional wooden barrels.