What Happens During a Chimney Inspection?

What a chimney inspection is

A chimney inspection is a structured look at the whole venting system to answer two questions: is it safe to use, and what does it need next. It covers the parts in the living room, the parts on the roof and, in many houses, the parts in the basement that carry boiler and water heater exhaust. NFPA 211, the national standard for chimneys, fireplaces and vents, calls for an inspection every year, and again after a chimney fire, a storm or anything else that may have caused damage.

It is different from a sweep. A sweep removes soot and creosote. An inspection is about condition: cracks, gaps, rust, water damage, clearances and anything blocking the flue.

Inside the house

The room gets protected first: a drop cloth on the floor and the hearth. Then the firebox is checked for cracked firebrick and open mortar joints, and the damper is opened and closed to see whether it moves freely and seals. The hearth extension in front of the opening is checked for cracks and length, and the distance to wood trim and the mantel is noted.

Above the damper sits the smoke shelf and the smoke chamber, the funnel that leads into the flue. With a light and a mirror, the inspector looks for loose or rough masonry, heavy creosote and debris such as nest material. Where the flue is straight, a good part of the liner can be seen from below.

• Firebox brick and mortar joints
• Damper: opens, closes, rust, warping
• Smoke shelf and smoke chamber
• Visible flue liner and creosote buildup
• Hearth extension and clearance to wood trim and the mantel

On the roof

Up top, the inspector checks the crown for cracks and overhang, the cap for rust, loose mounting and clogged mesh, and the flashing at the roof joint. The top courses of brick and their mortar get a close look, because that is where freeze and thaw do the most damage. From the top, the inspector can also look down each flue and see which flue serves which appliance.

Chimney height relative to the roof and nearby structures is noted too, since a short chimney or a taller building next door can cause draft problems. If the roof is too steep or unsafe to walk, that is noted, and the inspector checks what can be seen from a ladder, a roof hatch or a safe vantage point.

In the basement

Many chimneys in older homes around the region also serve the boiler and water heater. Here the inspector checks the connector pipe running into the chimney, its slope and joints, the thimble where it enters the masonry, the barometric damper on oil systems, and the cleanout door at the bottom of the flue.

Crumbled tile or mortar in the cleanout is a sign the flue lining is breaking down from the inside. Water at the base points to condensation or a missing cap. Rust streaks on the connector point to condensation too.

Clearances get a look here as well. Connector pipes should keep their required distance from joists, stored boxes and wood shelving, and the area around the boiler should be clear. Items stacked against a hot smoke pipe are a fire risk that is easy to fix on the spot.

What gets checked, part by part

Each part of the system is checked for specific problems, and each problem tends to point to a particular repair. These are the main ones.

• Firebox: cracked brick and open joints, often repaired with refractory mortar
• Damper: movement, seal and rust, sometimes leading to a new or top-sealing damper
• Flue liner: cracks, gaps and deposits, addressed by sweeping, repair or relining
• Crown and cap: cracks, overhang, rust and the condition of the mesh
• Flashing: lifted metal, tar patches and gaps that call for new flashing
• Connector and cleanout: rust, slope, debris and water, sometimes pointing to a liner sized for the appliance

Common findings in older homes

In older brick homes across the region, the same findings come up again and again, roughly in this order. Most are not emergencies, but each one tends to get worse with time and weather, so it is worth knowing which ones you have.

Items that affect safety, such as a cracked liner on a flue that vents a boiler or a blocked flue, are flagged first. Items that affect the life of the chimney, such as worn joints or a cracked crown, come next.

• A cracked or flat crown and missing or rusted caps
• Worn mortar joints in the top courses
• Flashing sealed with tar instead of set into the brick
• Cracked clay tiles or open tile joints
• A rusted or warped throat damper
• An oversized flue serving a newer boiler or a lone water heater

Inspections at different depths

Most yearly inspections cover the readily accessible parts described above. Some situations call for a closer look: buying or selling a house, a change of appliance or fuel, a chimney fire, storm or earthquake damage, or a problem that cannot be explained from what is visible. A closer look may involve accessing the attic or crawl spaces beside the chimney, or opening parts of the system.

If the inspector recommends going further, they should explain why and what it will show before anything is opened.

How long it takes and what you get

Most homes take under an hour. A tall chimney, a hard roof or several flues take longer. At the end you hear what was found in plain words, which items are safety concerns and which can wait, and any repair comes as a written estimate you can think over.

If the flue is coated in soot, the liner surface underneath is hard to see. That is why many homeowners book the inspection and a cleaning together: the sweep clears the flue and the inspector gets a clean look at the walls.

Preparing for the visit

Let the fireplace or stove go cold for a day. Clear the hearth and mantel, and make sure the attic hatch and basement are reachable. Gather what you know: when the chimney was last swept, when the boiler or water heater was replaced, and anything you have noticed, such as smells, smoke in the room, drips or animal noises. Those details point the inspector to the right places first.