Two carpenters agreed with Prokudin to build

Two carpenters agreed with Prokudin to build a wooden garage for him in the country by June 1. The cost of the work was determined in a written document called by the parties a “labor agreement”. It also contained all the conditions relating to the characteristics of the building being erected (garage size, foundation material, iron roof, etc.). Materials for construction pledged to provide Prokudin until May 10. Carpenters set to work in a timely manner and already on May 28 almost all the work was completed. They told Prokudin that on May 30 they were asking him to come for the acceptance of the work. May 29 was to hang the gate. On the night of May 28-29, the garage completely burned down due to a lightning strike. Prokudin, who arrived in the morning of June 2 to accept work, discovered a preserved foundation and an unidentified gate. Considering that a contract was signed between him and the carpenters, Prokudin refused to pay for the work done and demanded the construction of a new garage from the carpenters materials. The carpenters believed that since the work was done in full (except for the gate overhang), they are entitled to a reward, and they don’t know what the contract was with them. They were interested only in the amount of remuneration with which they agreed.
Disassemble the arguments of the parties. Whether the decision will change if the fire occurred on the night of 1 to 2 June.