The framing square is the correct tool used for stepping off the length of a rafter due to its design and functionality. A framing square, also known as a carpenter's square, features a large, flat body and a shorter tongue that form a right angle. This makes it invaluable for making precise measurements and cuts, especially for determining the lengths and angles needed for rafters in roofing structures.
When stepping off the length of a rafter, a carpenter can use the framing square to create accurate layouts by referencing the rafter length against the square's scales for both angle and rise/run calculations. This ensures that the cuts made will fit together properly when assembling the roof structure, which is crucial for maintaining the building's stability and integrity.
Other tools, such as the speed square, T-bevel, and builder's level, have specific uses that do not directly align with the function of stepping off rafter lengths as effectively as the framing square. While a speed square can be used for making angle cuts and layouts, it does not provide the same structural precision that the framing square does for full rafter assemblies. The T-bevel is useful for setting angles but is not used for measuring lengths accurately, and the builder's level is primarily for leveling rather than