Sweep or inspection: what each one does, and which to book first

Two jobs, two different results

The difference between a chimney sweep and an inspection is what each one leaves you with. A sweep is a cleaning job. When it is finished, the flue, smoke chamber, smoke shelf, damper and firebox have been brushed and scraped, and the loose deposit is bagged and on its way out of the house. What you get is a clearer passage for smoke and less fuel sitting inside the chimney.

An inspection is an evaluation. When it is finished, you know whether the structure is sound, whether any deposit inside could catch fire or choke the flow, and whether heat is getting too close to framing or trim. What you get is findings, walked through with you before the crew leaves, and a written estimate for anything that needs work. Nothing is cleaned unless cleaning was booked as well.

The two are easy to blur because one crew can do both, sometimes on the same afternoon. The test is what you hold at the end. If it is a clean flue and a brief note, you had a sweep. If it is a list of findings with each one explained, you had an inspection.

What NFPA 211 actually asks for

NFPA 211, the national chimney and venting standard, puts an inspection on the calendar every year, checking the structure, the deposits inside and the clearances to combustibles, and treats cleaning, maintenance and repair as work done when that inspection shows a need. So the yearly requirement is the inspection. Cleaning is conditional: it follows the inspection's findings.

The same standard lists a routine cleaning among the moments to examine the flue being cleaned, and it expects defects noticed during that work to be reported to the owner. That is why a careful sweep includes a look, and why that look is narrower than a full inspection. It reaches the surfaces the brushes touch and little beyond them.

When the sweep should come first

If you burn wood regularly and the flue has not been brushed since the last run of fires, start with the sweep, because deposit hides what an inspector needs to see. A crack in a tile under a coat of creosote is invisible. Brushing first turns the flue into something that can be judged.

The same holds when the signs point to buildup: black flakes on the damper plate, a sooty odor on days the fireplace is not in use, a fire that has become slower to draw. The guide on signs your chimney needs cleaning walks through each of those checks.

When the inspection should come first

Each of the situations below is a question about condition, not about deposits. Several are situations where NFPA 211 asks for a deeper examination than the routine yearly one, reaching into attics and crawl spaces and along each flue from end to end.

• You are buying or selling the house and nobody knows the chimney's history.
• A stove, insert or other appliance is about to be added, removed or swapped.
• Relining is planned for the flue.
• There has been a chimney fire, or a storm or other event that could have damaged the stack.
• The fireplace has sat unused for years and may be blocked.
• Water is showing up in the firebox or on a wall beside the chimney.

What each visit looks like on the day

A sweep day is mostly containment and brushing. Drop cloths go down, the opening is sealed around a filtered vacuum, rods and brushes work the flue from the top or the bottom, and the smoke chamber and shelf are scraped by hand. The visit ends with the debris bagged and a short note of what the brushes exposed.

An inspection day is mostly looking and measuring. Expect a light and mirror at the damper, time on the roof at the crown and cap, a trip into the attic where the stack passes through, and a tape measure on the hearth. It ends with the findings shown to you and, where something needs work, a written estimate.

When one visit covers both

For a fireplace or stove in regular use, the yearly visit can be a sweep and an inspection together: clean first, then examine the clean surfaces while everything is open and the drop cloths are down. That saves a second trip onto the roof and hands the inspection a clean flue to look at.

Ask for it that way when you book, so the visit is scheduled long enough for both. Ask too what you will have in writing at the end, since a combined visit should still leave you with findings and an estimate, not only a tidy firebox.

Gas units, factory-built fireplaces and idle chimneys

Gas makes no creosote, so there is little for a brush to remove, but the vent of a gas appliance still falls under the yearly inspection. Nests, rust-through and disconnected sections all block or leak exhaust. Servicing the gas appliance itself, cleaning it and checking its controls, is separate work done to the maker's manual.

For a factory-built fireplace, the owner's manual sets the cleaning and inspection instructions, and those come first. A chimney that sits unused still gets checked, because animals, leaves and water keep working on it whether or not a fire is lit.

What neither visit includes

Neither a sweep nor an inspection repairs anything. A cracked crown, a loose cap, a warped damper or open mortar joints go onto the written estimate as individual items, and you decide what gets done and when. Neither visit judges the roof covering either; failing shingles or tiles around the chimney are a roofer's call.

Glazed creosote is the other exception. A standard sweep's brushes skate over it, so its removal is written up apart from the sweep.

Questions worth asking when you book

Clear answers to the questions below tell you what the visit will leave behind: a clean flue, a set of findings, or both.

• Is this visit a sweep, an inspection, or both?
• Will the flue be examined from the top as well as from the firebox?
• What will I have in writing at the end?
• When you find a problem, is it written up separately so I can decide later?
• Does the stove or insert need to come out, and who handles that?