Final answer:
The horizontal member is known as a lookout, which is vital for securing the soffit material and ensuring proper ventilation and insulation of the roof structure.
Step-by-step explanation:
The horizontal member that extends from a rafter to a nailer or the face of a wall sheathing, which serves as the surface to which the soffit material is attached, is known as a lookout or sometimes as a soffit batten. Lookouts are vital components in roofing construction,
as they provide the means to secure the soffit, which protects the underside of roof overhangs and porch ceilings from the elements. The installation of lookouts is an important step in ensuring proper ventilation and insulating properties of a building's roof structure.
The horizontal member is known as a lookout, which is vital for securing the soffit material and ensuring proper ventilation and insulation of the roof structure.