。
Hirofumi put fiberglass insulation in the ceiling.
Literal
Hirofumi [topic-は] ceiling [to-に] fiberglass [possessive-の] insulation [object-を] put-in.
天井 (てんじょう, 'ceiling') is basic house vocabulary. グラスファイバー is the loan 'fiberglass' (glass fiber). 断熱材 (だんねつざい, 'insulation material') is a construction term: 断 ('cut') + 熱 ('heat') + 材 ('material'). 入れた ('put in') is the simple past. A straightforward DIY/construction sentence.