A chimney inspection covers 13 areas of your chimney to see if there is any damage that need to be corrected in order to keep your chimney safe for burning.
1) To check the integrity of the chimney
In order to check the integrity of the chimney a stress test is the only way to uncover possible earthquake damage. If your chimney is broken it is UNSAFE to use.
2) Check to see if the chimney has been built to fit code height requirements
You chimney must be 2 feet taller than 10 feet close to the roof or 3 feet taller at the ridge of the roof. If a chimney is too short then building it up to code height is required. If it is too tall a brace may be required depending on city codes.
3) Check to see if the chimney has a cap/ spark arrestor
The Chimney cap prevents water from entering the flue. If water is able to drip inside it can possibly over time wash any mortar away and cause any metal to rust creating many safety issues and costing you more money. The cap also prevents sparks from your fire from exiting the chimney and keeps critters from inviting themselves in your home unannounced.
4) Check the crown
The crown covers the top of your chimney and prevents water from seeping down between the brick and flue liners.
5) Check the brickwork and mortar
A very common problem with the lower section are heat cracks. This occurs when the chimney can't compensate quick enough to accommodate high heat thermal expansion and results in cracking. When this happens the cracks on your chimney are much like cracks on a windshield- they start off small but will grow over time.
The way to fix this is by diamond cutting out the cracked mortar joints and refilling it with fresh mortar making it like new. Diamond cutting is a very dusty job! If your chimney requires this procedure make sure to clear off or cover anything you want to be dust free.
6) Check the flashing
The flashing keeps any water from leaking into the woodwork of your home. Making sure the flashing is present and that it is properly caulked will keep you safe from water damage in that area.
7) Checking the flue tiles
This is perhaps one of the most difficult sections to check. Checking the flue liners involves three things:
1) To see if any of the liners are damaged because of high heat thermal expansion.
Any tiles that are cracked are immediately declared unsatisfactory. A tile that is cracked is a safety item because 1) the tile is fragile and could possibly cave in and fall down into your fireplace and 2) creosote can build up in the cracks and create a potential bomb out of your chimney. Tiles that are cracked in one place only can be parged to correct the problem. Tiles that are cracked in more than one place must be removed and replaced. If ALL the tiles are cracked in multiple places then the chimney must be rebuilt.
2) To see if there are any voids (missing mortar joints) between the liners
Tile voids are a common problem with chimneys that have no rain cap arrestor. When a chimney has no rain cap water is able to enter inside the chimney and after time wash away the mortar between the flue tiles creating a void. A tile void is a safety item because creosote is able to accumulate inside the separation and create a dangerous situation if it should ever catch fire. To fix this problem we perform what is called pyro-packing. Pyro-packing involved taking high temperature mortar and refilling the voids where mortar is missing.
3) To make sure that there is no creosote baked on the tiles
Creosote is a flammable substances that forms when your don't clean your chimney on a regular basis or are burning the wrong things in your fireplace. It is a sticky tar like substance that covers the inner liners of your chimney and also forms in the voids between your liners. The dangers of this is creosote once ignited acts like a fuse and will spread throughout your chimney until it reaches a dead end. Once that happens and the fire has no place to escape a potential blowout may occur. Creosote is also very dangerous to breathe in as it is very poisonous. Creosote is difficult to remove and must be acid treated. Click here for more info.
8) Check the moisture resistance
The bricks of your chimney are like sponges meaning they soak up water. After years of soaking in water the bricks of your chimney may begin to spall (flake off) in pieces and/or cause already existing outside cracks to get worse.
9) Check the smoke chamber for any missing parging, creosote buildup and lower tile voids
The smoke chamber is the first place in your chimney to collect creosote. Checking the smoke chamber for creosote is the easiest item to see but often the most overlooked. The last flue tile needs to be checked because the creosote that forms in the smoke chamber will also collect in the void of the last flue liner. The dangers of a lower void is that the creosote that accumulates can catch fire and potentially turn your chimney into a pipe bomb.
10) Check the damper and throat plate.
Rusting of the damper and throat plate is the most common problem in any chimney on Earth. Rusting occurs when water drips on any metal in the chimney. Repairs can be as simple as de-rusting the damper and throat plate or as complicated as completely removing the damper blade and installing a top damper system. We always recommend having your damper and throat plate de-rusted as it will save you lots of money in the long run.
The throat plate is a metal plate that runs up diagonally where the damper blade rests on in the 'closed' position. When the throat plate rusts it can cause a throat void.
The throat plate can also bend, warp and bow making normal throat void repair more difficult or impossible to do. As you can see from the picture the throat plate has warped far beyond a normal repair because it is now cutting off any possible way for smoke to exit the chimney. Cutting out the damper blade and throat plate is the only solution.
11) Check the fire box for any seam separations and spalling.
The seams are what hold the corners of your fire box together. The dangers of any seam separations is that creosote may enter and accumulate. Once the creosote catches fire inside any seam separation can spread rapidly into the woodwork of your walls. Repairing the seams can be as easy as re-pointing them (filling them with high temperature fire clay). As you see in the picture below once the seams get beyond what a normal repair can fix and allows the back wall to move then rebuilding the back fire wall is the only possible repair.
Spalling is a form of corrosion where water collects inside of your bricks and causes them to flake off like slate or shale. Unfortunately there is no repair for a spalling brick. Once spalling begins you must cure the cause of the problem which is having no rain cap arrestor. Once a rain cap arrestor is installed the spalling will stop. A spalled brick is more of an eye sore than anything. If spalling has claimed an entire brick or many bricks and allows the back wall to move then rebuilding the back fire wall is the only possible repair.
Fixing it with fire clay or cement will only act as a band aid and will eventually fall off. Parging the area that is spalling may end up becoming more of an eye sore than before.
12) Check hearth protection
The hearth protects the outside of your fireplace from catching fire. All hearths MUST be made of a non combustible material (brick, granite, tile, etc.).
If your hearth has tile facing on it we check to make sure that there are no voids between the tiles and the wall. The dangers of this is creosote can develop in the voids and can catch the woodwork in your walls or mantle on fire.
13) Check the ash pit and ash dump doors.
The ash pit/ dump doors cover up the openings to the inside of your ash pit. If your doors are missing animals and other critters can get in and will make that their home or possible move into your home where it is warm.