Before making a decision of doing a flat roof, you should take caution on the type and size of valley sheet ie, the valley sheet should be galvanised in a good guage and the valley size should be not less than 10inch to fasten cleaning and a large volume ratio for water flow, secondly avoid direct sand contact with iron sheets to avoid lasting, secondly the wall bracket should not go beyond one meter and lastly use only and only ordinary iron sheets. For more inquiries contact +