The horizontal timber piece provided at the apex of a roof truss which supports the common rafter is called A. Ridge board B. Hip rafter C. Eaves board D. Valley rafter

The correct answer is: A. Ridge board.

A ridge board is a horizontal timber piece provided at the apex of a roof truss which supports the common rafter. It is the highest horizontal member of a roof and runs along the length of the roof, parallel to the ground. The ridge board supports the common rafters, which are the rafters that run from the ridge board to the eaves.

The other options are incorrect.

• A hip rafter is a rafter that runs at an angle to the ridge board, where two sloping roof planes meet.
• An eaves board is a horizontal board that projects from the edge of a roof to protect the walls from rain.
• A valley rafter is a rafter that runs at an angle to the ridge board, where two sloping roof planes meet at a valley.