​A leaky chimney can cause deterioration and unpleasantness. Moisture can cause many problems to the chimney and flue. It can also damage drywall, ceilings, and cause your fireplace to smell. An open chimney top leaves the chimney vulnerable. This big open area resembles a giant rain gauge but is much more significant.
An open chimney lets in moisture, such as rain, sleet, snow, debris, and animals, which causes deterioration and an unpleasant smell. A quality rain cap works like a big umbrella, directing rain away from the flue opening. A chimney cap with a screen is the best option, as the screen will deter animals from wanting to nest in your chimney.
A chimney crown (or wash) is a barrier that prevents moisture from entering the cavity between the flue tiles and the interior of the brick (or stone). It starts at a gap near the flue tile and extends to the exterior brick, often with an overhang and a drip edge. Cracks in the chimney crown allow moisture into the chimney, and the cracks can expand when the moisture is frozen, accelerating the damage. Most cracks in a chimney crown can be repaired, but if severe, the crown can be replaced.
Chimney flashing and counterflashing is a metal material that forms a moisture barrier between the chimney and the roofing material. Defective or improperly installed chimney flashing can let water into the chimney and the home since It tends to follow the chimney into an attic or enter rooms below the chimney, damaging ceilings, drywall, and other materials. Repairing or replacing the flashing will direct moisture away from the gap between the chimney and the home's structure.
Moisture can wash out the mortar joints holding the flue tiles together. The flue tiles are the first line of defense against combustion products. If the mortar is missing, the tiles can shift, or at the very least, they will leave an opening in the flue. Moisture can also cause flaking of the flue tile and bring creosote and mineral salts through the mortar to the chimney’s exterior, leaving dark creosote and (white) efflorescence stains.
When moisture has caused flue defects, several solutions can be explored. If the mortar joints are missing, relining the chimney is one option, or resurfacing the flue may be necessary (the flue tiles must be intact and aligned). A chimney technician can use stain removal cleaners to remove stains on the exterior. Another option is waterproofing the chimney’s exterior if the moisture penetrates the brick-and-mortar (or stone) exterior.
As more moisture travels down the chimney and into the flue, damage can occur, such as eroded mortar joints in the flue, smoke chamber, and firebox, particularly the back wall. It can rust a fireplace damper, glass door, and screens. This moisture will continue to break down the fireplace and damper while creating an unpleasant smell from the wet soot and debris, particularly in the spring and summer. The fireplace can be repaired and the damper replaced, but the moisture must first be stopped. Cleaning the flue and smoke chamber may help, but often, the soot is already soaked into the masonry, and it is impossible to remove all of it.
The best way to prevent moisture problems is to ensure that leaks are taken care of promptly to avoid further erosion problems. Keeping moisture out of the chimney will prolong its life and reduce annoying stains and odors. By spending a little now, costly future repairs can be avoided. Take heart; if there is damage from moisture, it can be repaired by a chimney professional so you can continue to enjoy your fireplace.
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When looking up a dark chimney flue with a flashlight, you will see what the light illuminates in degrees of shapes and shadows. Remember, you will also be looking at it from just one angle. Visual acuity (clarity of vision) differs from person to person. It is a rating of a person's ability to recognize small details precisely. Many factors can affect the quality of a person's eyesight, one being brightness. Because you shine a flashlight into a dark chimney flue, similar to looking into a dark tunnel, the details you can gather with the naked eye are minimal. However, a Chim-Scan® Chimney Camera can provide a close view with adjustable lens angles and variable light brightness. This surpasses the naked eye, captures details, and provides images and videos.

Should a flashlight and the naked eye be used to inspect a chimney?
I taught chimney inspection classes for over 21 years and used a prop with hidden defects (the images at the right). Almost 99% of the time, the inspectors missed an opening within the chimney flue using a flashlight and the naked eye. These defects were only 17” from their faces. If a chimney technician inspects a flue with a flashlight and notes there were no defects, they risk opening themselves up for liability or lack of disclosure for missed defects. If the chimney was scanned with a camera the previous year, and no events were noticed, a flashlight may be sufficient for the inspection if you performed a chimney scan inspection the previous year and they didn't use their chimney.

Currently, in the chimney industry, inspections with a flashlight are allowed on a Level 1 Inspection at least once a year, during a routine cleaning of the chimney flue, replacement of a connected appliance with one of a similar type, input rating, and efficiency according to NFPA 211. However, are you really sure you could see everything?

The language in Level 1 (15.3.2.4) asks for verification that the flue or flues are free of combustible deposits and blockage or obstruction. But the language in Chapter 14 of NFPA 211 does state that if the flue liner has softened, cracked, or otherwise deteriorated so that it no longer has the continued ability to contain the products of combustion (i.e., heat, moisture, creosote, and flue gases), the liner shall be either removed and replaced, repaired, or relined with a listed liner system (14.9). Can you determine all of this with a flashlight?

A camera with a tilting lens captures angles and textures and defines the movement of the flue tiles.
The beauty of inspecting chimney flues with an adjustable tilt lens, like the J3D and Lighthouse™ Tilt Cameras, is that changes to the masonry are more apparent when looking at it from different angles. If I look only at the sides of the chimney, I may miss the fact that the flue tiles are severely misaligned. If I look straight down or up the chimney, I will miss openings between the clay flue tiles. I may also miss a hole in a flue hidden by severely misaligned tiles, as the photos show. Instead, when using these tilt lens cameras, I can see how thick a mortar joint is, how much mortar is missing, whether the tile has damage and whether there is a hidden breeching, amongst other defects.
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Illumination is critical to diagnosing defects. What do you see if you look down a chimney with a flashlight? Most likely, you will see shapes, shadows, and lines. It will be up to your brain to form a picture and decide if these shapes, shadows, and lines constitute a defect. How good is your eyesight? How good is your flashlight?

When scanning a chimney with a properly illuminated camera, you can pinpoint defects as small as hairline cracks or degradation. If you look down a chimney and see creosote, can you define it? Is it a dark mass in the flue? Can you tell whether it is glossy, goopy, or tarlike creosote? Or is it shiny – almost reflective when the camera illuminates it head-on? How is the texture - puffy, granular, light soot, tarlike, or glazed? Can you see surface degradation?

Not every chimney camera is the same.
Now that we have described the ideal chimney scanning system, you need to know that not all chimney cameras have a tilt lens and adjustable lighting. Not all lenses can spin in a circle. With some systems, the technician must properly turn the camera while inspecting and videoing the flue. This video often ends up a wobbly mess, which gives the viewer an inclination to car sickness. The quality of the camera and the ability to get clear, focused pictures are essential to finding and diagnosing defects. Unfortunately, a camera with poor images shines a bad light on the technician. If the customer can't see a clear picture of a defect, it's a credibility wrecker.
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In closing
A chimney can be seen as a unique appliance in the home. It is a channel whereby the products of combustions shall pass through and exit the atmosphere. A chimney may also be a part of the fireplace or heater's draft. It must keep the elements out of the home, yet not without closing off the drafting function. It is exposed to heat inside and cold outside. It is exposed to the elements - rain, snow, wind, and weather events. There is no doubt that it is integral to the home. When it comes down to having an inspection and you are a homeowner reading this, demand that the chimney is scanned with a chimney camera. Especially one with quality photos, such as the Chim-Scan® Internal Evaluation Camera System.
If you are a chimney technician, remember to use your camera on every job!

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When to use IRC and NFPA 211 for Chimney Inspections
Both the International Residential Code (IRC) and the National Fire Protection Association (NFPA) 211 books provide information on building chimneys, fireplaces, and appliance installations. Which book should I use for chimney inspections? The IRC and NFPA 211 both cover new construction of chimneys, fireplaces, and appliance installations. However, NFPA 211 goes one step further, offering a process for inspecting chimneys, fireplaces, and appliance installations since we see the world of chimneys and fireplaces after operating. The question above is commonly debated within the chimney industry.
Are you wondering which to follow for new construction? Most states require the use of IRC, and a few require NFPA 211. Some states have their own building codes and some areas within a state have their own codes. Then there are exceptions such as historical areas. Always check locally because there may be additional local codes required above and beyond IRC or NFPA and even state codes.
When it comes to prefabricated chimney and fireplaces, the installation instructions must be used. These instructions can usually be obtained online if you know the model number. The same goes for appliances. If you need to call the manufacturer’s help desk for technical assistance, be sure to also have the serial number. The manufacturer (and their installation instructions) must be followed for installation and supersede IRC and NFPA 211.
We suggest obtaining an IRC or NFPA 211 book if you don't already own one. If your area abides by IRC for new construction, you will still need NFPA 211 for access and inspections. Additionally, you may need copies of local codes and historical district codes. As a chimney technician or inspector, it's up to you to determine if the chimney, fireplace, and appliance installations are operational-ready based on inspection criteria. Your customers count on it.

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