The first step in making sure your chimney is safe and serviceable is to get a chimney inspection. When you get a professional to inspect your chimney you’ll receive a report of what it looks like inside and outside.
Levels of Chimney Inspections
Chimney inspections have “levels” with Level 1 Chimney Inspection being the most basic. It’s simply a visual inspection of whatever is easy to see during cleaning.
You probably want a Level 2 Chimney Inspection which involves looking at all the accessible areas (the attic, crawl spaces, etc) and, while not required, usually involves the use of a chimney camera to examine the flue tiles. A Level 2 Chimney Inspection is required (by NFPA and most codes) when changing appliances hooked up to a chimney, after a chimney fire or earthquake, and before a real estate transfer. This is the law in Maryland.
In your chimney inspection, the sweep or inspector should:
Check for cracks and weathering
Check for cracks and weathering in the masonry and the mortar joints. That means looking at the bricks themselves, the joints between them. If there are cracks in the brick or bad mortar joints here’s what needs to happen to fix it:
- When there’s a lot of bad brick at the top, the best solution is to take the chimney down and rebuild it.
- If there are a lot of bad mortar joints, take the chimney down and relay the brick. If the bricks are in good condition you can certainly re-use the bricks and, in fact, should for aesthetics – you want to match the bricks below if you can.
- If the damage is more minor, “re-pointing” is an option. This is where you remove a few bricks individually or where you just put some fresh mortar in where old mortar Is worn out. This is an OK solution for small problems, but it’s a terrible solution when a masonry structure is just plain worn out. It would be like putting a Band Aid on a cut artery. Keep in mind that repointing is aesthetically poor as the new mortar or brick is not likely to match the rest. Rebuilding is best option
Check for cracks in your crown (the cement on the top of the chimney)
Again, you make a difference between “big damage” and “little damage.” If your crown is anything but perfectly sealed, you do need to fix it because this is where all the damage below begins. Water that enters through the top of your chimney freezes and thaws all winter long, in time ruining the structure below.
If you have crown damage, here’s what needs to happen to fix it:
- Big cracks and masonry that is outright coming up in your hand obviously needs to be replaced. The whole crown should be removed and replaced with concrete. A lot of crowns were made with mortar mix and that’s not good- use concrete.
- If on the other hand you just have cracks in the top (and fact is most chimneys do) then you will be all right with simply sealing the crown. There are good latex sealants these days which hold for a very long time when properly installed.
Check for stability
It is not uncommon to see chimneys leaning away from the wall. What to do is not clear cut. If the chimney is leaning it’s very likely because the foundation of the chimney isn’t right. In any case, either the chimney moved away from the house or the house moved away from the chimney.
If the chimney is built as part of the foundation the house sits on, and had not broken away, then it’s safe to say the house moved somehow. To know this, you must dig around the base of the chimney to actually inspect the foundation.
If the foundation is good, here’s what needs to happen to fix the problem:
- You either have to tear down and rebuild the chimney or you must caulk the opening. More likely though, the chimney foundation was never part of the poured concrete of the house’s foundation and it has a “movement life” of its own. If so, here’s what needs to happen to fix it:
- First, tear down the chimney. Then take out the old foundation. Then dig the hole deeper (another couple feet maybe?) and pour a new concrete foundation. Finally rebuild a new chimney.
I know nobody wants to hear that and I know lots of people think about strapping the chimney to the house and drawing the bolts up tight. It is not a good solution. First of all, it may be illegal. More importantly, it doesn’t really fix anything, it only closes a gap. The chimney comes under new stress and will break in the middle, given some time. Don’t think about straps. It’s more of an 1800s thing.
Check for clearances from combustibles
A chimney professional will know code-specific things to check for, but anyone can make sure their chimney complies with the “3-foot, 2-foot, 10-foot rule.”
Take a look at the picture and you’ll understand immediately.
If your chimney doesn’t comply, here’s what needs to happen to fix it:
- In almost all cases, the solution is to raise the chimney. This can be done by adding rows of brick to a brick chimney, or by adding lengths of factory built chimney both to masonry or factory built chimneys. It looks a bit odd coming off the top of a brick chimney, but it is legal.
- Check the inside of the chimney- the flue tiles (liner.) Check the liner for mis-aligned tiles, for spaces between tiles, check for cracks or broken sections of tile liner. Check for “spaulling” i.e. little bits of the face of the tile breaking loose and building p at the bottom of the flue. The only way to really know is by video inspection. When you call your chimney professional, be sure to insist that you’re getting a video inspection. If not, hire someone else.
If you have any of the above situations, here’s what needs to happen to fix it:
- Pretty straightforward really- you need to reline that chimney. The particulars of how that’s done vary so much from one chimney to another that I can’t possibly cover it here. Suffice to say that the one thing you should ask for is to have the old tiles removed. It will cost more and a lot of chimney people would rather not do it because it’s not fun work. But this is your house and you want it done right if at all, right? Have the old tiles removed. The reasons are usually related to proper sizing and to the fact that there is probably creosote on the outside of the tiles where nobody can see it (but it can still catch on fire.)
Check for obstructions
These are usually obvious when cleaning a chimney. Or perhaps you have a tree hanging right over the chimney. If you have an obstruction, here’s what needs to be done to fix it.
- Just get it out of the way. Overhead branches too close? Cut them off. Bird’s nest in the chimney? Remove it. Debris at the base of the flue? Remove it. This one is obvious what to do, you just need to check to see if any problem exists!
Check for cleanliness
Sometimes a chimney is obviously clean just by look at it. If you can’t say that for sure just looking at it, then play it safe and have the chimney swept.
Check the connections
Wood stoves, fireplace inserts, gas or oil burners and hot water heaters all have pipes that connect those appliances to the chimney itself. They should be secured with three screws at every joint, have an uphill incline, be the right size, attached or joined to the chimney well and have proper clearances to combustibles. Make sure your chimney inspection includes all of these elements. And if something is wrong, here’s what needs to happen to fix it:
- it varies. Regardless, you need every one of those points to be in order. A bad connection is every bit as dangerous as a bad chimney. Probably more dangerous actually, so pay close attention to connections.
This should give you a good overview of what you want in your chimney inspection and what to listen for when the inspector tells you what needs to happen to fix any problems.