Steven Smalley, owner of Exterior Home Improvement, in Indianapolis, notes the telltale signs: waving, bubbling, studs uneven. And the first paragraph in his contract states that that siding will be completely removed.

When Jason Kersch, of Major Homes, in Queens, N.Y., explains to homeowners why he's removing all of the existing siding before installing the replacement product, he invokes the roofing analogy — homeowners better understand the concept of starting over. “No one wakes up one day and says they want a different color roof,” he notes. “They buy a new roof because they need a new roof. They replace siding because they want a new look.”

EXTRA COST ISSUES Major Homes works on houses throughout the New York metro area, replacing old aluminum siding, vinyl, wood shakes, and asbestos shingles. The only material Kersch prefers not to completely remove is asbestos shingles, which have to be remediated — those get sided over. All other siding gets torn off and replaced.

The cost of this sometimes causes homeowners committed to the least expensive price to balk. Kersch says he recently quoted a job that would take seven days; minus full tear-off it would be six days. His price included removing all the siding and installing housewrap. No sale.

Smalley says he provides homeowners with two prices on siding jobs: one with full tear-off, one without. The key selling point for tear-off is that siding over “builds the house out another inch. If your windows are flush, they're now going to be recessed.” He also explains that though he warranties siding jobs, he won't do so if the job is sided over at the homeowner's insistence, “because it's not my siding,” he says.

For Steven Jones, owner of Tulsa Renew, a home improvement company in Oklahoma, the question of whether or not to do a full tear-off before launching into, typically, a fiber-cement replacement job, depends on the circumstances. In many cases, total tear-off is “an unnecessary cost for the customer,” he says. “But in a lot of situations” — uneven wall surface or evident rot — “you have to tear it off.” But, Jones adds, “It's a bigger deal than people think, if you want to do it right.”