Years ago I dismantled several old motel cabins and a small older house to salvage various building materials, which were later used to construct a "new" home. This gave me some useful insights into what is worth salvaging and what is not.
Metal roofing is perhaps the most valuable manufactured item to salvage. The cabins we dismantled had aluminum roofing panels attached with spiral-drive roofing nails. Although care is required to remove metal roofing sections without damage, the long life expectancy of metal roofing (especially aluminum) makes it an excellent salvage item. Newer metal roofs usually are attached with screws, which makes damage less likely.
Common estimates indicate that up to 50 percent of the cost of new construction is in fixtures. Sinks, faucets, cabinets, cupboards, lights, baseboard heaters, fans, doorknobs, and other household details are often easy to remove and can be used directly in other structures. Some old-style built-ins—china cabinets, pantries, wardrobes—can be pulled out and reinstalled elsewhere. If you salvage more than you can use, trade or sell the extras. And remember: Older toilets typically consume from 3.5 to 7 gallons per flush (versus the current standard of 1.6 or less) and electric heating devices (stoves, ovens, heaters, etc.) will not be usable if you are planning to go off the grid.
Windows are a situational salvage item. If you can't use, sell, trade, or stockpile them for later projects, they will just sit around and take up space, possibly getting broken in the meantime. Some window types come out easily and safely; others aren't worth the trouble. Be aware that using old single-pane windows in cold climates may add up to more in energy losses than the cost of new windows. Keep other uses in mind: unheated structures, cold frames, or greenhouses.
Doors are usually easy to remove, and new doors of decent quality cost a fortune. Take all hinges, screws, knobs, latch plates, and related hardware, too. Often matching items will not be easy to find, especially for older doors that may not fit current standard hardware dimensions.
Planking of various dimensions and types may be plentiful in older buildings, built in the days before Sheetrock, particleboard, and plywood took over. Look for larch, oak, cedar, fir, spruce, pine, and other hardwood and softwood planks, possibly of a size and quality not seen since the last old-growth timber was cut and milled. Such high-quality wood is excellent for reuse in cabinetry and furniture. Or you can sell it for top dollar to cabinetmakers.
The last pieces of a building left to salvage are usually framing lumber, such as studs, sills, top plates, joists, and rafters. This is the underlying skeleton of a stick-framed building, and it usually comes apart readily. In older buildings, the framing lumber may be of such high quality that it is more valuable for uses in decorative elements.
Some materials do not lend themselves to efficient salvaging. Wood shingles and shakes (roof and wall), unless they're thick and in good shape, just get in the way of other salvage work. Lighter shingles and shakes are more useful for starting fires than for anything else (and then only if they're not painted or treated).
Sheetrock (or gypsum board) is essentially not salvageable; the same is true of most commercial insulation materials. Avoid reusing old rock wool ("filthy" best describes this stuff), fiberglass, and other undesirable materials.
Older buildings may have cedar shavings as ceiling insulation (ours did). This can be scooped up, bagged, and saved for pet beds or sachets for mothproofing drawers or closets. Don't reuse them as insulation; they're a fire hazard.
Fixtures, doors, and windows may be the only items to seek in new construction. Framing lumber may not be worth the effort. Of the common "modern" wood-based building materials, plywood is one of the few that can be readily salvaged.
Each salvage situation calls for its own evaluation of time versus money, quantity versus need, quality, appearance, and so on. Personal judgments are an important factor. An analysis blind to these values might make some salvaging efforts seem uneconomical, but to those doing the work it may be well worth it.
Most of what you salvage can be had with almost no need for power tools. Good hammers (one curved claw, one flat) and a "wonder bar" (a small multipurpose pry bar/crowbar/nail puller), plus leather gloves, safety glasses, dust masks, and ladders are the primary tools. Small hand tools (screwdrivers, pliers, adjustable wrench, pipe wrench) are occasionally useful, as are a full-size crowbar, a hand sledge, and a full-size sledgehammer.
A reciprocating saw (often called a "sawzall") with the correct blade types can cut hidden or stubborn nails, screws, and plumbing pipes that are blocking disassembly. If there is no power at the salvage site, consider borrowing or renting a generator.
Some physical strength and dexterity are necessary, but with patience, almost anyone can learn basic deconstruction skills. The only essentials are a willingness to pay attention to how things come apart and to listen to those with experience. In a group salvage effort, some folks can focus on the heavy work, some can take apart the "details"—and some can bring lunch and cold drinks.
From Communities magazine (Summer 1998). Subscriptions: $18/yr. (4 issues) from the Fellowship for Intentional Community, Box 169, Masonville, CO 80541-0169.