Examining the Framing Part 1

There are various ways to construct a house, and a variety of materials can be used, but more often than not you will be looking at homes using a method called light frame construction. This is the most popular building method in North America and Australia. It involves using softwood lumber to construct a frame which supports the structure.

Hardwoods can be better for construction, but they are more expensive. Softwoods are cut into dimensional pieces that are used to create the parts of the frame. Since this lumber is prone to damage by insects or moisture it is often chemically treated, so it will have a greenish yellow tint. Sometimes you may see a treatment that leaves a red/ pink stain on the lumber. With improvements to framing being made, you will see engineered pieces of wood from glue-lams (thick laminated pieces of lumber), to wood I-beams (where an oriented strand board, OSB, is used in sheet form between two pieces of lumber), to wood trusses (reminiscent of a train truss bridge). Since you will probably be buying an already existing home, the only place that you will be able to see the framing will be in the attic or basement.

The framing of a house supports the weight of the walls, ceilings, equipment, and roof of the home. The exterior walls are veneer walls, so it does not matter if it is brick or aluminum siding, the exterior wall carries no weight. In fact many of your interior framing for walls will not carry the weight of the structure either. This allows you to move them about when redesigning the interior space. The walls which carry the weight are called the load bearing walls. The exterior framing will carry weight, but the best way to tell if a wall may be carrying a load in the interior is in the attic. Where ever you spot larger beams running along the attic, there is framing below it to support that weight. If you are planning major remodeling, you will have to consider how that weight will be supported if the framing is removed from below that beam.

Load bearing and non-load bearing walls are built the same way, so the terminology of the members is the same. Traditionally in light frame construction, all of the pieces were horizontal or vertical, with the only diagonal members being found in the attic construction. Diagonal braces are becoming more common in frame construction for walls, since they add more stability. Horizontal members are called joists (floor joists and ceiling joists). Vertical members are called studs. Anytime an opening is made into the framing, the weight above the opening needs to be dealt with by creating a header (or it is also called a lintel). The header shifts the load to studs, which hold the header in place. These studs are called cripple or jack studs. Trimmer studs are used to frame in the interior of the opening. Sill plates are the framing pieces that run along the top and bottom of the studs. A sill plate that attaches to the foundation is called a sole plate.

Moving into the attic, you will see the rafters. This is the lumber that holds the sheathing for the roof in place. The rafters are held together by vertical beams called collar ties, and by braces below. A purlin is a board that runs on the top of the brace perpendicular to the rafters. A strong back holds the brace in place at the bottom of the brace. This will all attach to joists that are at least six inches deep. The insulation will sit in the cavities created by the joists.

Contractors will not purposely try to confuse you, but it is easier for them to use the correct terminology, because it describes the item perfectly. There are many terms which describe a particular piece, but usually the words “stud” or “joist” will follow, so you should have a good comprehension of what they are talking about once you hear those terms. Some remodeling may need to be done in the home that you purchase, understanding framing basics may help you save some costs. A contractor will find a way to achieve your desire, but if you plan your walls based on existing load bearing walls staying put, you can save a great deal of money.

(The ohotgraph above shows rafters and collar ties. The purlin is the board running along the rafters below the collar ties, and the diagonal boards coming down are the braces. Insulation is covering the joists.)

Frank Schulte-Ladbeck, TREC#9073, http://www.fschulte-ladbeck.com