What warranty or guarantee should I look for in winter pest services?

A re-service or re-treatment warranty is a written commitment that if pest activity continues or recurs within a defined window, the company returns and addresses it at no additional charge. This is a promise a company can actually keep, because it's about its own labor and materials, not about controlling a wild animal population it doesn't fully own. Look for the specifics: how long the window runs, what triggers a free return visit, and whether it covers the same pest or any pest.

State consumer guidance on service agreements — cited here for its regulatory framing, not as New Hampshire-specific law — describes exactly this kind of guarantee as conditional and structural, not an outcome promise: a company can reasonably warrant that it will come back and redo the work, because "there are many conditions and/or structural characteristics that can cause even the most professionally applied materials to be less effective than desired," and the honest response to that reality is a return visit, not a claim that it won't happen.

An unconditional "pest-free guarantee" or "100% pest-free home" promise is not something any honest company can deliver, because a treated structure sits inside a surrounding population of rodents and insects that continues to exist regardless of what happened inside your walls. The FTC's Advertising Substantiation Policy requires that a company have "a reasonable basis" before making a performance claim, under threat of Section 5 enforcement — a blanket pest-free promise, made against a population the company doesn't control, is legally shaky in addition to being physically implausible.

This doesn't mean the underlying work is worthless. It means the promise attached to it is the part to be skeptical of. A company confident enough to say "we'll come back if it doesn't hold" is making a claim it can actually keep; a company that promises the mice simply won't return is making one it can't.

Before signing, find the specific language covering: the length of the guarantee period, what triggers a free return visit versus a new charge, whether the coverage is pest-specific or general, and what's explicitly excluded. If that language isn't in writing, it isn't enforceable — a verbal assurance from a technician doesn't survive a dispute the way a written clause does. This is exactly the kind of documentation worth keeping alongside the written inspection report from your initial visit.