House Structure Basics

Regardless of what type renovation project you may be planning, a basic understanding of your home’s structure and mapping of its systems will help you better assess project complexity, renovation requirements, costs, and time involvement. As well as whether or not your renovation plans are something you can accomplish yourself, or if they are even feasible.

Styles of Framing

There are two basic styles of house framing:

• Balloon Framing
• Platform Framing

Balloon framing has studs that run uninterrupted from the roof to a sill plate on the foundation. Studs in platform framing, on the other hand, are attached to floor-level bottom plates (horizontally running framing members along the floor), and ceiling level top plates.

Most homes built after 1930 use the platform style of framing. One reason is that this type framing is easy to alter during home renovations. That is because the support structure for each story begins at the floor level of that story, while balloon framing uses wall studs that extend from the foundation walls of the structure to the roof.

The type framing your house has will determine complexity of renovation projects that alter the structure’s frame. Framing type also determines what type temporary structural supports will be required during the construction period.

Determine the structural framing type of your home by either referring to the original blue prints of your home, or consulting with a building contractor or your local building inspector.

Aspects of Framing

There are four aspects of home framing that work together to form a solid structure:

• The roof
• The walls
• The floors and ceiling
• The foundation

Roof framing involves the construction rafters, or the purchase of prefabricated frames. Rafters are most often made using 2X6 or larger lumber spaced 16 to 24-inches apart; spanning from the exterior walls to the ridge board or beam, at the peak of the roof. Ceiling joists usually link the ends of opposing rafters, creating a structural triangle. Rafter ties or collar ties are sometimes used for additional support.

Trusses are usually made using 2X2 lumber joined with metal plates or fasteners. Standard trusses have bottom and top cords with interconnecting webs for stability. Trusses can be found in many homes built after 1950. The down side of prefabricated roof frames such as these is that they cannot be cut or altered in any way.

Wall framing uses studs; vertical framing members spaced at regular intervals that make up the interior and exterior walls of the home’s structure. While commercial structures most often use metal studs, residential dwellings most often use wood; either 2X4 or 2X6s.

Floor and Ceiling Framing consists of joints; the ends of which rest on support beams, foundations, or load-bearing walls. Joists always run perpendicular to their supports, and carry the structural load of floors and ceilings. Most joists are made using 2X10 or larger lumber.

Ceiling joists generally use smaller lumber, 2X4 or larger, since they support only a ceiling finish and sometimes small storage space. Blocking or X-bridging is usually installed between joists for added support.

Floor joists used in balloon framing are nailed to the sides of the continuous wall studs. Upper-story joists gain added support from 1X4 ribbons that have been notched into the studs below the fire blocking – nailed between each joist for fire protection.

Foundation wall framing and a girder, or main beam, supports the frame of the house. This is true regardless of whether the house has balloon or platform style framing. In turn, the foundation framing is supported by the earth that surrounds it.

Mapping out House Systems

Mapping out house systems such as plumbing, wiring, and heating is a critical part of home renovation planning. Likewise, understanding aspects of house structure and type of framing used is also important.

While many do-it-yourself homeowners feel comfortable handling less complicated renovation projects themselves, larger, more complicated projects often require at least some input from a professional building contractor.

Aside from wood framework, home structure also involves the following:

• Plumbing
• Wiring
• HVAC system (heating, ventilation, and air conditioning)

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The Comprehensive Guide to Home Renovations