15 smells, honestly decoded

What's that smell in your house?

A real differential diagnosis for a strange smell in your NH home — across pest, mold, plumbing, HVAC, electrical, and gas. Describe it, or pick the smell or the room below.

Describe the Smell

Our AI runs the differential and finds the closest decode

NH-licensed (#782664)Same-day service · Manchester · Nashua · Concord

Some smells can signal a real hazard — those 10 are flagged Check safety first below. If you smell gas, leave and call your gas utility or 911 from outside.

Start here

Go by what you smell, or by where it's coming from.

Pick whichever you know. Most smells trace back to just a few causes — and pest is the single most common one here.

Filter by the most likely cause

Showing 15 of 15 smells & locations

What does it smell like?

Pick the smell that matches — each opens the full differential.

Musty / mildew smell

Mold or mildew from an underlying moisture problem — often with no visible mold, especially in a basement or crawl space.

Mold & moisturePestPestView

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Rotten meat / spoiled food smell

Spoiled food, garbage, or a disposal if it traces to the kitchen; a dead animal in a wall, duct, or crawl space if it doesn't.

Decay / foodPestPlumbingView

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Fishy / chemical / burning smell

Overheating electrical wiring, an outlet, or a failing appliance component — a fire hazard, not a pest problem.

ElectricalHVACGasView

Post-treatment smell

A faint solvent or carrier smell from the treatment that fades within a day or two as surfaces dry — normal, and not a sign anything went wrong.

OtherPestPestView

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Skunk-like smell

Actual skunk spray, outdoors and seasonal — but a skunky smell indoors or near a gas line should be ruled out as a possible natural-gas leak first.

GasPestPestView

Ammonia / urine smell

Rodent urine — acrid, ammonia-like, concentrated in enclosed spaces like closets, cabinets, and wall voids.

PestOtherOtherView

Dead-animal / decay smell

A dead rodent decomposing in a wall void, ceiling, crawl space, or HVAC duct.

PestHVACPestView

Check safety first

Lingering / unidentified smell

There is no single most-likely cause — the smell's character and location determine which of the causes below applies; use the triage table to route yourself.

PestMold & moisturePlumbingView

Where is the smell?

Pick the room — we rank what most often causes a smell there.

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Attic

Rodent, squirrel, or bat nesting — with accumulated urine, droppings, or guano — is the most likely cause of an attic smell; a roof leak causing mold is the main non-pest alternative.

PestDecay / foodMold & moistureView

Crawl space

Moisture and mold are the dominant cause of a crawl-space smell in New Hampshire homes, by a wide margin over rodents, a dead animal, or a sewer/septic issue.

Mold & moisturePestDecay / foodView

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HVAC vents / ductwork

Burning dust at first heating-season startup (benign) or a dead rodent in the ductwork (persistent, putrid) are the two most common causes — an acrid, worsening burning-plastic smell is the one that needs immediate attention.

HVACPestMold & moistureView

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Basement

Mold or moisture is the single most common basement odor in New Hampshire — sewer gas from a dry floor-drain trap and rodents are the next two most likely causes.

Mold & moisturePlumbingPestView

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Outdoors — yard, porch, deck

Skunk spray or denning, or a dead animal under a deck or porch, are the most common outdoor odors near an NH home — a rotten-egg smell right at the gas meter is the one to treat as an emergency.

PestPestDecay / foodView

Check safety first

Garage

Rodents nesting in the garage — extremely common in NH garages in fall and winter — is the most likely cause; stored gasoline and vehicle exhaust are the two genuine hazards to rule out first.

PestDecay / foodOtherView

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Walls / ceiling void

A dead animal decomposing inside the wall or ceiling void is the most likely cause — but a burning, hot-plastic, or fishy smell from a wall must be treated as a possible electrical fire hazard first, before any pest explanation.

PestPestMold & moistureView

Smell it, but can't find the source?

If it's a pest odor — a dead animal in a wall, a rodent nest, urine near the baseboards — we locate and remove the source, not just mask it. Family-owned since 2017, serving Southern New Hampshire.

Book a same-day inspection (603) 785-0118