chimney problems

[gmason]

We had out masonry chimneys cleaned out the other day and they found chunks of flue liner chipping out with the soot on the flue for my woodstove in the basement. Said we probably had a chimney fire at some point. Anyway, he poked a flashlight up the shaft and said he could see one of the tile flue liners had a chip/chunk out of it and said we shouldn't use it at all anymore until it got fixed.

Our house is about 6 years old and the woodstove has only been used for 3 seasons and not all that much for 2 of the 3. Should a clay flue tile break this soon like this normally? How does one repair such a problem. I believe the liner tiles are 8"x8" and of course they run from the basement up to the top of the chimney some 30'+.

gary

 

[beenthere]

It does sound like a chimney fire at some point. Safety on continued use will depend on what is outside the broken flue tile that forms the chimney. Sometimes tiles are cemented into a concrete liner that is inside a brick chimney. Mine is like that. There are three layers of "protection", although I wouldn't count on the concrete layer to be continuous (without voids). Some chimneys are just the tile flue, which is the other extreme.

There is a system of relining the 8x8 flues with a 6" round stailess steel liner that is cemented into place. It is likely the best way to go. I believe another system is having a moving form that is used to pour a concrete (cement) liner around as it is moved up the 8x8 tile in the chimney. Contact some chimney outlets for more specific details.

 

[knucklehead]

The easy answer is to hire a mason to look at it for you. I guess the best thing would be to get that chunk, or talk to the person who found it, and relay that info to your mason. Did you see the chunk? Can you determine whether it is a chip or is the flue broken through? Maybe it's a chip and they will shrug it off. But I'd think about getting a pro's opinion, especially if there are other potential brittle areas. Did you have a fire? Did you hear a whooshing sound once, or find ash and junk on the roof or ground? There are little fires in chimneys all the time, but what damages them is the intense ones.

How handy are you, and will you sleep at night with your own repairs? This might sound like a funny question, but the time and trouble in making your own repair, coupled with the subsequent worry, sometimes isn't really a savings in the long run. Having said that......

I have read about a couple methods for repairing stuff that is out of reach. One is to pull a burlap bag tightly filled with straw (or moss, or similar material) and topped with mortar up through, which would fill the voids on the way. Kinda like a Q-tip in reverse/w3tcompact/icons/tongue.gif! That's an old fashioned method of sealing cracks I have read about. I've also seen ads for flue installation where they insert an inflatable tube down the chimney and pour mortar around it - I don't think you need that.

I am running a wood stove in an old (35 years) concrete block chimney lined with 8x8 tile, and the they seemed to "wander around" when they built the chimney. It's as if they cut holes in the house and aimed at them with the chimney. You can see the ends of the tile a bit when you look down or up the flue, and there is a noticeable curve in it. Our flue also ends where the pipe entrance is, about 48" off the floor. The builders mortared spikes into the block, and set the whole tile liner on that - a scary and cheap way to save a couple pieces of tile and avoid cutting one. We had a few cracks, even a large piece broken out, but they were easy to reach, and I patched them up and smoothed the entrance with mortar. I mortared over the nails to seal the flue at the bottom, too, something that makes me wonder if the nails will now corrode, but I've seen metal in mortar before and it seems to be fine. We used to wonder if we would wake up to the sound of all the flue suddenly sliding the last 4 feet to the cellar floor! We've got a couple seasons on the wood stove now, and it seems to be operating well.

Might be the best thing to do is call a mason. I'd like to know how you make out.

 

[Anonymous Poster]

Gee, are you living near me? Did the chimney sweep tell you he could have MrVideo Inspector come over and perform a video inspection of your chimney in a few weeks cause even though MrVideo is backed up with work, he can pull a favor?
Can you say SCAM?
For less than 25 bucks you can buy a video camera on Ebay that you can attach to the end of a pole, and look at your own chimney from the inside. I just performed this "BIG JOB" for a friend of mine who is doubly disadvantaged Blonde & Female, because the "Sweep" gave her the same story about a chipped clay liner. Fortunately, I already had the camera.
Since you didn't specify, exactly what are the "chunks" you found, concrete or clay? It's quite normal to find minor spalling of clay tile due to frost, and concrete or more correctly mortar from the joynts between the clay tile. When the tile are laid up, very few masons bother to reach down inside the tile to clean up the joynt.
While there are many honest chimney sweeps, there are also many more who have found an additional source of income from scamming uninformed customers. The sad reality is that the scammed ususally think Mr Sweep is the greatest thing since sliced bread because he saved their house from burning down.

 

[Stonewall]

I have to second Franz. We have had good luck with sweeps so far but have been warned about some - Trouble just seems to follow them where ever they go. If you can video the tiles and see for yourself that there is not any place where the tile is completely gone then you are probably alright. If you are missing a piece of tile then don't use the ciminey untill it's fixed and DON'T count on the concrete behind it to keep you safe. We respoded to a fire last month where an old "summer cabin" was in year round use. The stone and mortar chiminey could not stand up to prolonged use and rotted through. The fire crept through dead spaces and insulation from many alterations and additions. It never really got roaring beyond the room w/ the firplace in it but it took forever to chase down and put completely out. The occupant lost almost everyting to fire or smoke damage. The cabin is still standing but has extensive damage to the roof and interior load bearing walls.

 

[beenthere]

Your cabin story is interesting, and the mortar and stone was, as you said, old. I would not put it in the same context as this 6yr old chimney and too quickly assume that the newer chimney isn't still functional. Franz had a very good suggestion as well as a valid warning about chimney sweeps.

Checking out the sweeps findings would be no. 1 priority.

 

[gmason]

Well, after doing some research on this problem, I can't believe they haven't outlawed brick chimneys. Basic, brick chimneys cause many house fires each year. Seems brick and mortar doesn't hold up to high heat(>1000degres). That the clay tiles crack very easy and that the mortar and fire smoke just don't like each other. Literally eats the mortar over time.

I've found a system that you take a Stainless Steel flex pipe and wrap some installation around it and slip/pull it down your flu. The pipe is about $20/ft for 6" and another $3-$4/ft for the insulation, clamps, fittings and top cap.

Now to be blown away, 2 chimney folks have given us estimates of close to $200+/ft to do the job. That's ~175/ft for just the installation...ouch /w3tcompact/icons/shocked.gif

Has anyone had this done to there chimney? Working well for you?

thanks