What is the name of L or T shaped carpentry tool?

Answer 1

Layout tools, tape measure, framing square, chalk line, pencil, etc, are used to layout where the walls go on the deck, where the studs, doors, windows are located on the plates, the stair stringers, etc.

Answer 2

The L-shaped tool with measurements on it is called a square. The T-shaped one with measurements on the side is called a T-square.

Answer 3

It's called a carpenter's square