Harijaya Insulation Surabaya Sell Galvalum which is an iron-based material with aluminum and zinc coating. Because it is made from iron, galvalum is very suitable to be used as structural material, especially as a sturdy and strong roof truss. Harijaya Insulation Surabaya Sell Galvalum which functions as an outdoor roofing material, gutters, fences and other needs including large buildings or residential houses.