Basics

Most carpentry projects-from making simple shelves to building walls-require that you square the work. Check for square at every stage of your work: corners, uprights, and board ends.

Making sure that work is plumb and level is equally important. Walls, cabinets, doors-nearly every permanent installation-must be plumb (perpendicular to the earth) and level (parallel to the earth). Don't assume existing walls or floors are square, level, or plumb. Most often they are not because of imperfect construction or settling that has taken place over the years. Techniques shown in this section will help you keep your carpentry projects straight and true.