How to say “The builder said we should insulate the gable first — that's where all the heat escapes.” in Japanese
In Japanese
業者さんに言われたよ。まず妻壁を断熱しないと、熱がそこから全部逃げるって。
Gyōsha-san ni iwareta yo. Mazu tsumakabe o dannetsu shinai to, netsu ga soko kara zenbu nigeru tte.