Understanding Siding and Framing
Before you order siding materials, be sure you understand how your walls are put together. Most homes have 2X4 or 2X6 studs (which are 1-1/2 inches thick) positioned 16 inches "on center," meaning 16 inches from the center of one stud to the center of the next stud. Some homes are built with studs on 24-inch centers. However, the spacing between the wall's corner and the next-to-last stud will usually be a shorter distance. At windows and doors there will be additional framing members, but if the framing has been done correctly, they will not interfere with the regular on-center spacing that runs throughout the wall.
Be aware, however, that framing is not always installed correctly, especially in older homes, where stud spacing may be irregular. And some studs may be installed out of plumb. If your siding is installed with nails driven into studs (rather than into sheathing), it pays to spend a little extra time confirming the location of every stud.
It is important to know what sort of sheathing you have. If it is solid plywood or OSB, some types of siding can be fastened to it. However, if the sheathing is made of a fibrous material, gypsum, foam insulation, or other soft material, it is not firm enough to hold a nail and you must install the siding with nails driven into the studs. In this case, you must also position any joints in the centers of studs; adjoining pieces can be attached to the same stud.
The sheathing should be protected with house wrap (which is generally light in color), building paper, or roofing felt. These products have undergone improvements over the years, making them more resistant to moisture while still allowing the house to breathe.Horizontal Siding
Horizontal siding may be beveled, in shingle form, or tongue-and-groove. It may be made of wood, fiber cement, or pressed wood. If the sheathing is solid plywood or OSB, you may be able to attach siding to it. In most cases, however, nails should be driven into the studs. At the bottom of the installation, a wood strip, additional layer of siding, or special starter strip makes the bottom piece flare out a bit.Brick or Stone Veneer
Brick or stone veneer is held together using mortar joints. Metal wall ties placed at regular intervals secure the wall to the sheathing. Small ropes placed near the bottom make a "weep hole" where moisture can exit, thereby protecting the sheathing from wet rot.Balloon Framing
Most homes are built with platform framing, meaning there is a single or double horizontal 2X member at the bottom and the top of each floor. In addition there is usually a wide rim joist providing a solid nailing surface between each floor. An old home may be built with balloon framing, in which case there are no plates or rim joists.