A Review of the Structure of Your Home

The framing of your home is the foundation, floors, walls, and roof which all tie together to form a solid structure. These are the actual boards which make up the floor joists, wall studs, and roof trusses or rafters. There are two types of framing used in home construction as noted in chapter 1 – platform framing and balloon framing:

• Platform framing – the style of framing used in most modern construction projects. For each story of the structure, wall studs extend from a bottom plate at the floor (or foundation) to the top plate which is either attached to floor joists of the next story, or roof trusses. The floor structures for each story are platforms that extend to the perimeter of the house. Because each story has its own support structure, this style framing is much less complicated when making alterations.
• Balloon framing – commonly found in older homes; consisting of wall studs that extend from the foundation to the roof structure – even multiple story structures. The first story rests on the foundation; second and third story levels are supported by 1X4 ribbons set in notches in the stud walls.

Both styles of framing are supported by the foundation and a main beam or girder, in the center of the structure. In platform framed structures, the load-bearing walls are easy to identify. They have a double top plate; consisting of two layers of framing lumber.

All exterior walls are load bearing. As are interior walls that are aligned above the center support beam, or any other support beams included in the structure.

Service System Review

It is equally important to understand the building service systems of the structure, as outlined in chapter 1. As well as the location of their components; plumbing sewer and supply pipes, electrical wiring and circuit loads, HVAC plumbing pipes, air ducts, and wiring.

When the renovation plan is just a re-design of existing floor space, chances are building service system components may only need to be moved, if affected at all. However, if you add floor space in a renovation design, keep in mind that it probably will place added demands on existing services, and upgrading system capacities may be necessary in order to meet them.

Plumbing systems usually consist of a drain-waste-vent system or DWV, and a fresh water supply system. DWV systems operate on gravity; the proximity of a vent is crucial to proper operation of each drain. Water supply lines are under pressure, but can be routed almost anywhere to suit a plan.

The electrical system is made up of many wiring circuits running through the frame walls, floor, and ceiling of a structure; stemming from a central electrical service box. They may be routed and configured in countless ways, making it difficult to follow wiring runs for each individual circuit.

Mapping the electrical system can be simplified by turning each circuit breaker off in turn to see which outlets and fixtures are connected to it. Following each wiring run is not necessary, but each fixture, outlet, and appliance connected to the circuit should be noted to accurately determine loads and capacities.

A forced-air HVAC system will have a furnace that heats the air and feeds it to a main supply duct. This in turn feeds branch ducts that supply heated air into each room or area of the structure. A second series of ducts returns cold air back to the furnace. To map a forced-air system, follow the ducts from each room or area back to the main duct, and the main duct back to the furnace.

Hot water or steam systems use a network of pipes that carry hot water or steam to radiators that heat the area. Some systems just have one pipe that connects all radiators together in a loop. Other systems may have an individual feed and return for each radiator.

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The Comprehensive Guide to Home Renovations