Besides doing regular Home Inspections, I occasionally get called to evaluate more specific problems----like where a leak is coming from, why the chimney is falling off the house, or if the roof will make it through another winter. These kinds of consultations are kind of fun because I like playing detective. Unlike a home inspection, I can get “invasive” if I need to. Since most of what goes on in homes is not “rocket science,” it usually does not take too long to figure out what is going on. The other day I got such a call to figure out some severe cracks that had developed on the face of the fireplace surround. Here is a picture of the fireplace and one can easily see the long horizontal crack, two tiles down from the mantle. The question? What caused the crack? With no sign of chimney or foundation settlement, I had to scratch my head a little harder to come up with the cause. The chimney was nice and straight and showed no sign of separation from the home-----as sometimes happens with these older installations. In short there was nothing wrong with the chimney from a structural point of view. However there were some factors, that when looked at together, led me to the answer. The mortar joints were really bad----there were actual gaps all the way through the mortar into the chimney flues. There had been previous long term leaking (before roof was replaced) into the chimney structure where the chimney attached to the house. This leaking was apparent at the damaged walls and wallpaper at both sides of the fireplace. Also neither flue had a proper hat for a long period of time. All of these conditions have a common denominator----WATER. Another thing one has to know about the chimney is that, at the time the chimney was built, it was common to put too much lime in the mortar. Lime in mortar makes the mortar very plastic and sticks to your trowel like crazy, making laying the bricks a lot easier. The problem is that the mortar is much weaker----especially when exposed to water----and especially when exposed to LOTS of water over time. As these old mortar joints are repeatedly wetted, the joints expand a little bit. Imagine, if you will, each joint of the chimney expanding even 1/64 of an inch. In an installation of 64 rows of bricks one could possibly see an accumulation of an inch of additional height. In the fireplace pictured, the tile finish surface has been installed over the brick chimney structure. If you could count the rows of bricks behind the tile they would add up to approximately 18 courses of bricks. If each mortar joint expanded 1/64 of an inch, the mantle would be lifted approximately ¼”----pretty darn close to the width of the gap in the horizontal crack. This next picture, if you trace the line of where the mantle hits the wall, shows how the paint and wallpaper tell us how much the mantle has been raised---see how it is pretty much the same amount as the width of the crack? See----it wasn’t rocket science after all. 
Charles Buell
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PS, for those of you that are new to my blog (or for some other "unexplained" reason have never noticed)all pictures and smiley-face inserts (emoticons) (when I use them) have messages that show up when you point at them with your cursor.
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Charles...
Excellent post, and good detective work!
But it was your title that grabbed me. We say that at work all the time "you must be doing crack!" lol
Wow, Charles, I never considered what Home Inspectors do when not inspecting homes for us. Thank-you for the insight...
Great detective work. Okay, so now that we "know" what caused the problem. What's the solution (repair?)
Richard, thanks----I know, a lot of people use the phrase.
Paul---no shortage of trouble for us inspectors to get into:)
Alan, excellent question. But it is a "cosmetic" concern:) Seriously, there is not much you can do to fix the problem, but if you can keep water out of the chimney it won't get any worse. The tile work will have to be redone.
Great work. You are probably one of very few that would have looked for the fireplace to rise, when first observation would have been to look for a drop. You've been at this a while, and maybe have seen this at least one other time and it stumped you?
Hi Charles: Are you Sherlock Holmes re-incarnated? Sir Arthur Conan Doyle?
:)
Wow! That was genius! I would have never known that about the mortar. Thanks for the lesson! This might be good to link to from the newsletter this week...if you don't mind.
Ed---well of course that is what I looked for too---at first, but when I had to rule that out, I had to think of something elese. I have seen expanded mortar joints lots of times.
Matt---not that I am aware of:)
Lizette---have at it.
you always have the most interesting things to re-blog. to crack or not to crack that is the question. cw
Nice to see you Chery (Whereyoubeen) Willis:)
Mr Charles,
I would suggest, for your own benefit, that when you admit to using illicit substances that you might want to make sure that you are not bragging in a public location.
Sgt Nutsy Wallenda
You tell him Nutsy!!
Good observation skills there Charles! Nice Post.
Charlie,
I cannot believe that you would write that when there is a cop at AR reading most of your posts. What a big goof.
Nutsy---as usual---you make little to no sense.
Tony, thanks----and pay no attention to Nutsy
Steve---as usual----you make little to no sense. (does this seem repititious to anyone?)
Do you work for insurance companies. I used to work claims and managed some property programs. Guys like you were important.
Gene I would if asked:)
If you go to court, you will be found guilty for admitting to the use of crack. I am sure of that.
Nutsy
That 1/64" is the same for flooring.
Nutsy has a point too...
In manufacturing, my old job, that is referred to as tolerancebuild up and can throw of precise measurements. I bet that wood stove aggravated the problem.
Nutsy---maybe so---but I didn't inhale.
Jay---absolutely
James the wood stove is another issue. The owner told me that he paid to have a metal liner installed, but none was in sight:)
Charlie,
I think lots of us on here would rather that you keep your crack out of the conversation. Take it over to Sparky's Plumbing.
Steve, sad but true
You did a good job of sleuthing, sounds like. I like the idea of counseling on home problems. Do you charge for the service call?
Barbara, yes I do. $150 minimum plus $50 an hour after the first hour----not many make me hang out more than an hour:)
I get a lot of insight, perspective, and appreciation of the value of your service from your messages. Thank you!
Thanks Dwight---glad to be of help. I would also like to welcome you to the rain---have fun!
I have to say I learned something from this post. My first guess would have been chimney settling/ movement.
Harold, thanks, it was pretty interesting to figure out.