The Wood Roof is a slanted building-block covered with wooden shingles that you can use as a roof-tile or for other purposes (it can be rotated).
It can be crafted in your Crafting Menu (default key "Q"), after the according crafting-recipe has been unlocked by
- crafting or finding blocks of Wood Walls (can be found in Stone Treasure Chests and Obsidian Treasure Chests)
- crafting or finding blocks of Wood Floor (can be found in Stone Treasure Chests and Obsidian Treasure Chests)
To craft 8 (blocks of) Wood Roofs, you'll need (as of R43 in May 2017):
- 1x Twine, made from Vines in a Processor
- 1 Stone Rod made of Stone, Limestone or Bedrock in a Processor
- 2 Wood Rods made of any kind of Wood (except corrupted wood) or Logs in a Processor
- 4 Wood Slabs made of any kind of Wood (except corrupted wood) or Logs in a Processor
Crafting Wood Roofs is one of the unlocking requirements of the crafting recipe for Stone Roofs.
Even though it is a wooden building block, the Wood Roof currently (as of R26 in December 2015) is fireproof. Even when throwing Fire Bombs at Wood Roofs, they still will not go up in flames.