Sooner or later all brick chimneys need to be tuck pointed----you know, where the mortar joints have to be repaired. This is especially true of older homes where the mortar itself might not have been very good, and where age and missing hats has taken their toll on the chimney from the inside-out. Chimneys 
actually fair quite well from normal weather conditions. But, leave the chimney caps off so that water can get into the structure, deterioration can happen more quickly. Add to this, improper venting of gas and oil appliances and deterioration is guaranteed.
Sometimes the whole chimney needs to be tuck-pointed. Other times just doing portions of the chimney is enough----like the portion above the roof perhaps. Some times it is just the portion near the ground that is in poor condition. If the joints easily scrape away with a pen knife repairs are warranted. If the mortar is completely missing it is a "no brainer," like in this picture, where the pen knife not only scrapes the mortar away easily, but actually fits in the joint.
Deterioration of this chimney was at the point where some of the bricks will need to be replaced along with proper tuck-pointing.
Sometimes I am able to get close to the chimney on the roof, but I am not able to see down the flues. I can usually reach my camera up over the top and snap pictures of the condition of the inside of the flues. In this case the camera was able to see that bricks were falling inside the chimney where they may have already damaged, or will damage, the gas furnace metal liner. These metal furnace liners are difficult to assess by the home inspector. There really isn't an easy way to know whether a brick has fallen inside the flue and ripped a hole in the liner or not. When we see a brick leaning against the liner as in this next picture (and ready to fall) we do have to wonder though if one hasn't already fallen, and have to recommend that continuity of the liner be verified by the heating contractor.
If, in the Winter, we can see the furnace exhaust coming out of the chimney around the outside of the metal vent----sometimes even out though the missing mortar joints----instead of coming out of the cap----it is a pretty good indication that the liner is not continuous. Maintaining brick chimneys can be expensive but not nearly as expensive as replacement.
Charles Buell
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Early in my career there was a man who really blasted an old house or two here in Searcy. He'd take his finger and scrape the mortar. If it was sandy he'd say there was too much sand in the mortar and the brick wall would continue to disintegrate. I've noticed it many times since then. This blog reminds me of that.
Barbara, when the mortar starts to feel all sandy---time to re-do.
Hi Charles,
When we lived in southwestern Michigan, a block away from Lake Michigan, we had a 1920's home in St. Joseph, Michigan. Our neighbors had to retuck their brick and mortar, but ironically, our home only needed a total of 10 bricks around two window areas. We loved the bill we received, since it didn't look at all like our neighbors. LOL
;>)
The trend seems to be a preference for gas fireplaces vs. wood burning ones. Posts like this make me glad both of my fireplaces are gas ones :)
Ann-Marie---sounds like you lucked out:)
Ardell, I often recommend conversion to gas as an alternative to costly repairs to a chimney that would make it safe for wood burning. In our area I would say that the vast majority of chimneys build before 1945 fit this scenario---especially if they have had gas and oil fired furnaces venting into them. Making these structures safe for wood burning can sometimes mean replacement, whereas with tuck-pointing and lining the flue they can be converted to gas at a much lower cost---plus you actually can get some heat out of the thing:)
Charles,
The last home I owned/sold in Louisville, Kentucky had these problems with the chimney to the point that the first buyer decided not to buy the home. Fortunately a second buyer came along and purchased it knowing that they needed to repair the chimney. At the time I had no idea the chimney had problems.
Sean Allen
Charlie,
Boy you sure were lucky to find a swiss army knife at that inspection. I lose stuff, don't find it.
Sean, lots of homeowners have no idea of the condition of their chimneys---people think brick is "forever."
Steve,---it is good to be lucky:)
Great post. Most chimneys is SoCal are damaged by earthquakes. I don't think I have ever seen one as bad as the one in your photos.
I never understood why there are so many chimneys in Seattle anyways. Nad it seems like every house has one and they all lean (in the same direction) as I recall. But seriously, It doesn't even really get that cold in Seattle so why bother. You know cold in up state New York is when your spit freezes before it hits the ground. I mean, can't you get a space heater for the three days out of the year that the temp actually drops below 45? Make shoddily put together brick walls out of thoes deconstructed chimneys I always say.
That brick teetering on the edge looks like a harbinger of doom for anything that crosses it's path on the way down. Bricks don't have the vocal cords to yell Brick on the way down. I hope the mice,roaches, bats, birds, and squirrels are wearing hard hats. Ouch!
Yes Klee, compared to Syracuse we are all sissies out here----for sure. People still seem to want their 70 degrees however:)
Charles - Chimneys should be looked at on a yearly basis; we always try to check ours every spring. Most people never even think about the importance of maintaining their chimney and some of the dangers that are not visible. Good post.
The chimney and fireplace are so often neglected. Almost always they seem to be full of creosote, cracks, holes, no liner, etc.
Chimneys are holes in the roof in which you pour money. Although necessary years ago, most of them today are just water leaks and maintenance issues waiting to happen...
Yikes! But I do declare, Mr. Charles - that is the MOST decorative mortar joint I have EVER seen!!
That metal liner looked dinged down a few feet. Can't be in great shape... I don't like metal liners, even stainless steel - I find that in a few years they have rusted through. Maybe that's why so many sweeps recommend them?
Jay, your right. I always make a point in my reports that there is no way I can verify the continuity of those liners---good job for someone with a spetra-scope. I think they often get trashed draging them up or down through an old brick chimney.