Monday, October 10, 2011

The Low down on Advanced Framing.

Saving materials through advanced framing
takes some planning.. but its worth it.  
Here are some rules:

Frame walls with 2x6s on 24-inch centers rather than 2x4s every 16 inches can save a lot of wood and increase the energy performance of a house because it makes more room for insulation. Stack the framing Aligning framing members between floors transfers loads efficiently.

This means that you can omit the double top plate in favor of a single one. It also means a better-quality nailing job of the plywood that spans these transitions. Place doors and windows on the grid Moving door and window openings so that they line up on the 2-foot grid reduces waste and, again, leaves more room for insulation. Use less wood in the corners Exterior corners can do well with fewer studs and more insulation in them. The same goes for where interior partition walls meet exterior walls — less wood, more insulation. Omit unnecessary headers Walls that don't carry roof loads — for example, most gable-end walls — don't require structural headers over windows or doors.


Less lumber means more insulation
The whole point of advanced framing, also known as optimum value engineering (OVE), is to frame a house so that it meets its structural requirements without wasting material. A welcome corollary is that the same house will have more room for insulation inside the walls and will therefore be more energy efficient than a conventionally framed house. Minor downsides, for example, attaching trim in areas with less structural lumber, and wider spacing of siding fasteners, are easily overcome.


Load paths must line up
The main principle of advanced framing is to eliminate unnecessary lumber. For example, double top plates can be eliminated as long as each joist and rafter is lined up with a stud and partition walls are tied into intersecting walls with steel strapping.
Lining up framing materials in this way may require the designer to draw up a framing plan for each wall and floor.
Use more engineered wood
OSB, finger-jointed studs, laminated veneer lumber, and I-joists are all examples of reliable building products that can replace conventional plywood and large-dimension sawn lumber. Pressure on old-growth forests is reduced, waste is reduced, and better performance / often results.
Omit needless wood
Using two studs instead of four in outside corners saves a lot of lumber. Instead of using the same header size over all openings, engineer each header for the load it will actually carry. Headers in non-bearing walls can be eliminated entirely.
Consider insulating sheathing
Building scientists recommend replacing OSB or plywood sheathing with rigid foam insulation. This reduces the transfer of heat and cold through wood framing, a phenomenon known as thermal bridging. Diagonal bracing and shear panels can provide racking strength. For more complete information check out the articles links :-) 

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