One Thing After Another

[Berner]

Sometimes it feels like I will never get there...

Today I climbed to the top of the chimney to take the old concrete cap off and get a good look down the flue. After I jacked the ladder up and chiseled the cap loose I was throwing around my weight trying to shimmy the 100 lbs of concrete off the top. This is when I noticed a little bit of give to the chimney. Ugggghhhh.

It's a exterior masonry chimney that is in desperate need of repointing. This is project number one come springtime when the weather becomes more favorable for repointing. The chimney runs with the house to the top of the first floor and then it extends upward about 8 feet where the roof pitches toward the peek. I am a 200 lb guy that was really throwing my weight into the top of the chimney but it definitely had a little bit of rock to it. My first thought was that this should never happen. However after thinking about it, anything that is erected 8 feet with no support is probably going to have a little bit of give to it.

My house was built in 1880 and I would expect the chimney to be around the same time frame. Am I paranoid to be skeptical of something that has stood for over 100 years? I imagine repointing it in the spring can only help its structure but should I be calling for an official inspection?

Anyone shake the top of the their chimney and feel a little bit of rock?

 

[begreen]

An earthquake shook our 80 yr old chimney quite a bit in 1996. By the time it ended the top of the chimney sticking out of the roof had rotated about 30 degrees. I'm surprised it didn't come down. The mortar was old and there was no masonry liner. Be careful and have yours inspected. You don't want it moving when you are up against it with a ladder.

 

[chimneylinerjames]

At 8' out of the roof, don't worry, sounds about normal. Now as far as repointing goes, it is recommended when the bricks are still in good shape and just the mortar is bad. If the bricks are solid, go ahead and repoint.

 

[Corey]

Hard to say without actually seeing it. Bricks don't have too much 'give' - thats one reason they are used for structural components. Though I guess it's possible you were pulling some of the mortar joints loose. One thing I would ask - 8 feet in the air, what were you comparing the chimney movement to? Is it possible the ladder / wood roof or anything else in the 'equation' was bending or flexing and just giving the illusion it was the chimney moving?

 

[Berner]

Hard to say without actually seeing it. Bricks don't have too much 'give' - thats one reason they are used for structural components. Though I guess it's possible you were pulling some of the mortar joints loose. One thing I would ask - 8 feet in the air, what were you comparing the chimney movement to? Is it possible the ladder / wood roof or anything else in the 'equation' was bending or flexing and just giving the illusion it was the chimney moving?

I'm 100% sure that it was the chimney moving. I had an eight foot fiberglass ladder leaning on the chimney from the pitched roof. It's a stone chimney that hasn't been used in 25 years. When I bought the house there was a ridiculous growth of vines from the bottom all the way to to the top. The mortar is awful. Cracks that you can see from 30 feet away.

Does anyone have any experience with chimneys that are in desperate need of repointing and how that effects their structural soundness?

 

[Ashful]

Does anyone have any experience with chimneys that are in desperate need of repointing and how that effects their structural soundness?

I have a little experience with this... but first, are you saying this is an original, un-lined stone chimney? No clay liner? If so, you're going to need to get it lined with something prior to use. Any give in the structure is obviously at the mortar, the joints opening on the side against which you placed the ladder. An unlined chimney is dangerous in many regards, whether it be allowing flue gasses into your living space, clearance to combustables, the collection of creosote, or the likelihood of further mortar failure inside during use.

If it's lined with clay tile, and the stack was moving independently of the clay tile, there's a chance it's still useable. I'd be very skeptical of anyone able to make that determination, though.

 

[BrotherBart]

This is a picture perfect candidate for a poured in place liner. Takes care of the lining issue and adds some structural rigidity to the whole thing.

 

[Ashful]

How much do those poured liners help with the structural aspect? I imagine it might fill in gaps from missing mortar on the interior of the stack, but being an insulating lightweight material, does it have any compressive strength? Would definitely want to get the outside of the stack in shape first, if going that route.

 

[MnDave]

Am I paranoid to be skeptical of something that has stood for over 100 years?

Given that building safety standards 133 years ago were probably slim-to-none... you are smart to be skeptical.

However after thinking about it, anything that is erected 8 feet with no support is probably going to have a little bit of give to it.

No. Stones and mortar should have no give. Your chimney is disintegrating. I doubt that "tuckpointing" is going to correct the "give".

Call a professional for advise.

MnDave

 

[Berner]

If it's lined with clay tile, and the stack was moving independently of the clay tile, there's a chance it's still useable. I'd be very skeptical of anyone able to make that determination, though.[/quote]

Thanks for all the belp guys.

It is lined with terracotta tile 7.25x12". I did have the chimney liner cleaned, he gave me an inspection and gave me a quote of two grand to repoint the chimney. He didn't physically get up on a ladder and feel the give but how can anyone tell if it is repairable or not? I guess I'm skeptical of him being able to make that determination as well. I was planning on running 6" rigid liner all the way to the top.

 

[Ashful]

Well, a 6" liner would make the quality of the terra cotta irrelevant, particularly if you wrap the liner, and would also likely give better stove performance, less creosote, etc.

If the stone hasn't really shifted or come down, it's always structurally salvageable by re pointing. Remember, mortar is simply gap filler, not adhesive. Gravity holds your masonry together, not mortar.

 

[jharkin]

Given that building safety standards 133 years ago were probably slim-to-none... you are smart to be skeptical.

I disagree. There were no formal rules back then but a lot of the materials used where a lot more durable than whats available today and things tended to be overbuilt. I'd like to see the modern house build from particleboard, plastic and staples that will outlast a colonial structure with an 8in oak post and beam frame!

Ive got a chimney almost twice that age that is quite usable with a metal liner installed.

Berner:
DO get that chimney inspected by a pro, but do some research and find somebody experienced in restoring old chimneys. It might be that a poured in liner and a good pointing is all it needs, or it might need to be completely rebuilt. The right pro will know. No matter what you do, be aware that in 1880 there is a chance that your chimney is built of soft brick and lime mortar. If so re-pointing it with a hard portland cement mortar will only accelerate the damage. The mortar MUST be softer than the brick so if the existing mix is straight lime that might be what you need to use for pointing.


EDIT: I missed that you mentioned its stone, not brick.

 

[MnDave]

I disagree. There were no formal rules back then

That's interesting jharkin... you say that you disagree... but then in your own words you agree.

MnDave

 

[jharkin]

I just disagree that the lack of a building code necessarily meant it was built poorly. I guess I didn't make myself clear.

 

[MnDave]

I just disagree that the lack of a building code necessarily meant it was built poorly. I guess I didn't make myself clear.

I understand what you mean about the possibility that because there were no standards that people typically over-built everything.

I still think that since he could rock an 8 foot section of stone on stone with 133 year old mortal he needs to be very skeptical.

Putting a liner and using mortar vs insulation might prevent it from failing in a catastophic manner but that could be expensive and might be cheaper to tear down and put up a Class A. The performance improvement alone would offset the cost in 5-10 years.

MnDave

 

[begreen]

I still think that since he could rock an 8 foot section of stone on stone with 133 year old mortal he needs to be very skeptical.

Putting a liner and using mortar vs insulation might prevent it from failing in a catastophic manner but that could be expensive and might be cheaper to tear down and put up a Class A. The performance improvement alone would offset the cost in 5-10 years.

MnDave

BB, you been up there rocking chimneys again?

The performance will be roughly the same whether using a poured-in-place liner or a metal chimney. The aesthetic difference on a old place will never be equal.

Find a mason with a great reputation and get some on-site advice. We're just armchair viewing over internet packets. You need trained eyes to determine the fate of this chimney.

 

[Ashful]

... and do your research on mortars, so you know what questions to ask. You don't need to know more than a mason, but you do want to be educated enough to flush out the guys who are just going to use some S-type mortar mix on an old brick chimney!

I recently interviewed a mason for some work on my house (I could keep an army of them busy with this place...), initially thinking this guy didn't know portland from lime. I quickly learned otherwise, when he went way over my head with his various different mixes for different age and types of brick, and red shale vs. limestone vs. granite, etc. That's the mason you want!

 

[blades]

Should not move with your weight. Structural integrity of mortar joints has failed. Not unusual. With failed mortar, water has the perfect opportunity to infiltrate, adding to the destruction not only of the chimney but interior ceilings and such. Tuck pointing may save it on a temporary basis, correct repair requires tear down to a level of still good mortar and then rebuild. This what a good mason will tell you. Likely in the $4k cost wise. An insulated liner installation should still be done. Unfortunately this type of problem is like cancer due to infiltration of water and will keep spreading agravated by the freeze thaw cycles of your location. A lot of this has cropped up in the last 30 years or so with the advent of the High Efficiency furnaces coupled directly to masonary flues- insufficient heat in the combustion exhaust to drive out the condensates which are acidic in nature and attack the mortar joints. Drop a camera down the flue and likely will see many voids in the terracotta joints as well.

 

[Ashful]

Blades, that's quite an assessment for never having laid eyes on it. A price and everything! Do you have ESP?

 

[blades]

No ESP, personal experience.

 

[Berner]

Should not move with your weight. Structural integrity of mortar joints has failed. Not unusual. With failed mortar, water has the perfect opportunity to infiltrate, adding to the destruction not only of the chimney but interior ceilings and such. Tuck pointing may save it on a temporary basis, correct repair requires tear down to a level of still good mortar and then rebuild. This what a good mason will tell you. Likely in the $4k cost wise. An insulated liner installation should still be done. Unfortunately this type of problem is like cancer due to infiltration of water and will keep spreading agravated by the freeze thaw cycles of your location. A lot of this has cropped up in the last 30 years or so with the advent of the High Efficiency furnaces coupled directly to masonary flues- insufficient heat in the combustion exhaust to drive out the condensates which are acidic in nature and attack the mortar joints. Drop a camera down the flue and likely will see many voids in the terracotta joints as well.

Oh Yes I can see from the top that there are a few cracks and misaligned terracotta tiles.

Thanks for all the great help guys. As usual I think I'm going to need to become more educated on this to hire someone who is competent to make a determination of the structural integrity of the chimney. Someday I will be burning wood. That's a promise!

 

[Ashful]

Misaligned tiles is one of the two most common reasons for stuffing a stainless liner down a terra cotta-lined chimney. Had the same problem with one of my chimneys here a year ago.

 

[Berner]

Misaligned tiles is one of the two most common reasons for stuffing a stainless liner down a terra cotta-lined chimney. Had the same problem with one of my chimneys here a year ago.

Yes I did the paint can trick and was successful with getting it down the chimney. I wrapped the bottom with duct tape to extend the diameter to 7" and was able to get it all he way down the chimney. It took a little encouragement in a few spots (letting it free fall for a few feet) but I'm optimistic that with a little encouragement I will be able to get the liner wrapped with 1/2" insulation all the way down. That's assuming that the chimney is good to go and doesn't need to be rebuilt.