Saving leaning 1798 chimney

[Tpt life]

He posted porch work in the other thread. Otherwise I would not have bumped this. 

[Tom King]

Success!!!  We had a slight collapse right inside the entrance passage from the outside for the concrete to flow through to the inside, blocking it.   Story later, but short story right now, Mike and I carried the rest in buckets to fill in the firebox.  It's all in place like I wanted it now. 

I've been talking more this morning than working.  We were finished by 9:30.  I just ran home to take a shower, and get into some dry clothes.  Going back over for more interviewing.   More later

[Tom King]

There was no one still there when I went back.  Since it didn't fall down, I don't know if we'll get any kind of coverage for it, or not.  Long story, but I'm dead tired.

[Tpt life]

Dead tired, but still standing. Sounds like that phrase could do double duty. 

[Tom King]

I hadn't had much sleep the last couple of nights.  These kinds of things, and especially unorthodox concrete pours, will often go sideways, and require another gear to be grabbed.  I was not really worried about what would happen, but just anxious I guess.  Turned out I was right.

  We couldn't use a wheelbarrow, for several reasons in the house, and neither Mike, nor I had poured concrete with buckets before.  The truck driver was one I knew, and requested.  I had helped him out of a jamb one of the first time he'd ever delivered concrete, maybe 35 years ago, and he has always patient, and helpful since then.  He said he'd never put concrete out of the truck into buckets before, and especially not with the chute sticking in a front door.  I knew we couldn't make it having to go up even a few steps.

There was someone there taking pictures, and video, but I have no idea what she got. 

It was raining lightly this morning.   I called the plant and said I thought we'd better cancel at 7:30.  They're about a half hour away, so I thought I was early enough to cancel.  She said they had already loaded the truck, so I said, maybe we'll get lucky.  I was fully expecting to have him dump 3 yards of concrete in a hole at my place, since any moisture to amount to anything would make the path back in there to the old house too soft for a concrete truck.

 As we drove over there, we were heading under a Really dark cloud.  It never amounted to anything but a medium drizzle, but that just made the humidity miserable, and us soaking wet.

No one else showed up when we first started pouring concrete, with the truck backed up to the outside of the chimney, and racing the rain, we didn't get any pictures.  People started to show up as we were having to move the concrete truck for the bucket phase, so there are some pictures of that somewhere.  Mike and I were fully immersed in the process, so I didn't slow up long enough to take a picture. 

[Tom King]

I ran over there, and took some pictures before it got dark.  I'll post some tomorrow.  It couldn't have been any better.  On the good end, and good side of the outside face, there were some open cracks between stones that I didn't put mortar in, because I thought the concrete would not possibly make it down there.  It did, and ran out of cracks between stones right at ground level-couldn't have been any better.  There was also signs of water wicking out to the face of some of the mortar that I did put in lower cracks, just in case.

[Tom King]

Here are the pictures, for anyone still paying attention.

First picture shows the inside of the firebox, now filled with concrete over 3' tall, and supporting everything that wasn't supported before.  They had some additive that the driver put in when he got here, that made it flow WAY better than adding water to the mix, and it's supposed to not make it lose any strength, like adding water does.  He put one gallon of whatever it was in the three yards of concrete.  It not only made it flow great, but the rocks didn't settle out like adding water does.  I don't have any idea what that additive is, but it absolutely made this job go easier.

The second picture shows a block of wood where I had left barely enough room for the truck's chute to fit.   Myrone put the chute right where we needed it, within an inch.   I was guiding him with hand signals to Mike standing out where the driver could see Mike.  I told Myrone that he couldn't dare touch the chimney, and he didn't.  About halfway into the pour, with the mix slowly going in, and around a corner to get into the firebox, the leaning stones moved the slightest bit (I had braced it all up, about as good as we could, but could only use that single room wall to brace the leaning stones against, but I'm glad it all held as well as it did), and a few of those soft bricks fell down, blocking the passageway.  I went inside, and elbow deep in concrete, I was able to get one brick out, but not the other one, so we had to move the truck, and go to moving it in buckets, for the last half filling the firebox.  The outside stayed filled being held by those fallen bricks.  I put that block of wood, with a brick on top of it, to hold the concrete back at that gap for the chute.

Third picture is just the overall view of the outside, with it filled with concrete.

The fourth picture might seen insignificant, but that's down at ground level on the outside, near the left corner.  I had pointed mortar in the cracks between the stones, to keep the concrete from oozing out.  I thought it would not get down that far near that corner, but it did!!   It couldn't have been any better.  It can't fall collapse now.  The hose nozzle is pointing to where that ooze is.

Next steps will be to redo the shoulders of the chimney to keep rain water from running down through it.  The interior bricks are just laid with the sandy dirt from the house location.  The harder, exterior bricks are all nicely tied in with Flemish Bond, but you know how sand runs when it dries out.  That was part of the structural problem.

Once the shoulders are finished, we will excavate some under the left side of the base, and pour a massive footing for that side only.  That side does not need to be jacked back up.  Once that side is well supported, the other side will be excavated out from under it, another lower footing poured, leaving enough room for jacks that can pivot the chimney back up into proper, plumb position.

I don't know when , if ever that will be done.  First, they're going to have to come up with enough money to pay me for this part, but at least, it's not in imminent danger of falling down.

I was told that there were a lot of other pictures taken, but I haven't seen any yet.  These were ones I took yesterday evening, when I went back over there to check on it. 

As far as I know, this is not something that has been done before, but that's kind of what I do every day.

[treeslayer]

Congratulations on a job very well done Tom, I’m sure there are not many people in the country that could accomplish that feat, get paid and take a couple of days off , you earned it!

[Tom King]

Tonight, party in the house we rebuilt the tornado hit porch on, this week.   They want a Powerpoint presentation of both jobs.  I'm still too tired.

edited to add:   I think I'll take the laptop, and projector, and just use the pictures I put in this thread.

[Tpt life]

I am learning. It may seem this is a one off feel as you go, but it is more of an exposé of a problem solving approach. I may never save a chimney, but I have saved field stone foundations. This provides a few new tools in my bag. 

[Chestnut]

On 8/3/2019 at 12:14 PM, Tom King said:

I don't have any idea what that additive is

They call it super plasticiser or water reducer. Not sure what the street name is for it. I'm surprised you got concrete to flow out those cracks at the bottom it looks like that admixture is defiantly doing it's job. In college the lab had a concrete press, we got to experiment with the different materials that make a concrete mix and then test cores for strength. You could easily take a 3,000 psi mix remove some water add in the water reducer and get a 4,500 psi mix with the same maybe even better working properties.

 

[Tom King]

This started out as 3500 lb. mix.  The said the additive worked best in that strength concrete.  Looks like they were right.  It actually sank down in there about an inch, and a half between when I left in the middle of the day, and went back that evening.  So it went somewhere down in it, which couldn't have done anything but good.  The inch and a half didn't bother anything.  I poured it up past the level of the bottom layer of bricks that needed support anyway.

Working on my stuff today.

[Tom King]

This morning, we went over to start laying bricks to get some support under the face bricks that don't have anything under them.   I didn't know exactly what we would need, so we just carried my small 10" brick and tile saw, and a few bags of premix mortar.  It gets hot in that spot by 9:30 in the morning, so I told Mike to just mix one bag of mortar, and we'd see how far it would go.

I was thinking that maybe we've mix some concrete to build up the level behind the face bricks, but once I got into it, I decided I'd rather do the fill with mortar, and new bricks.  We went home, and found a supply of leftover modern bricks with a lot of holes in them, which will help with bonding strength to the mortar. Tomorrow morning, I hope to get those unsupported face bricks some support from underneath.

I don't feel like there's time to wait for lime mortar, so like I have done before, I'm using modern portland cement mortar, but leaving about an inch of the joints clear of mortar on the outside, to be later pointed with lime mortar.  Lime Mortar is another long story, but this is not about that, right now.

The bottom courses of brick were not laid real straight, and pretty to start with, so I'm trying to go with that flow.  I am using reinforcing wire between the courses.  What I had in my leftovers was wire for 12" block walls, but that will work fine for this Flemish bond.

I'm more concerned about getting support under those bricks just hanging in the air, than I am about taking the wooden bracing down, so the forms can wait.  It's actually been kind of convenient to have the 2x12's for staging for the bricks to figure out which ones to use where, and which ones need cutting.

My nerves are finally back to normal after playing Russian Roulette Jenga with hundred pound stones inside the base for several weeks.

 

[Tom King]

We laid a few more bricks this morning.  I hadn't really figured out exactly how I was going to get good support under that hanging layer of Lime Mortar, but thought I'd figure something out once I got to that point.  I didn't want to go pecking at that layer of Lime Mortar, for fear that I might loosen bricks above it.  It would come right off with the right tap, but it's secure like it is, so I feel better about leaving it.

The trouble with leaving it is getting the bricks below pressed up into it good enough for really good support, but not to make the joint any fatter, or have to blend in mortar later.

I decided to taper the bricks, so I could butter them top, and bottom, and as they are pressed into place, it squeezes the mortar, both above and below.  I just freehanded the bricks through the saw, and sliced some teeth into the sawn sides for good bite to the mortar.

That worked pretty good, but I'm going to let a brick coming in from each end set up over night, so I can really pack more mortar behind it the next day.

Overall, I'm pretty pleased with how it looks like it's going to turn out.  It now has better support under all the face bricks than it's had for a while.  I got good support under the corner too.

I'm going to have to saw the bricks thinner for the last two rows to the end.  I'd rather not have had to do that, but I still feel like we're on borrowed time, so want to get it all supported.  The right end crushed the corbel-ed rows between the stonework, and the flat face of the brick below, and I didn't really feel like we had the luxury of taking more time with it to jack the brickwork part of it back up above the stonework.  So, it will be a little bit wonky, but there will be much more there for people to look at, so we'll just live with it. I thought about shortening the height of that row, but it's a corbel step, so thought it would make the difference stand out even more if one of the stepped rows tapered down.

 

 

[treeslayer]

coming along nicely Tom, well done, I’m interested in your thoughts about whoever built that chimney in the first place , experienced ? Amateur? working with the best that they had? they must have known something It stood for a long time. 

[Chestnut]

I'm curious about the bricks. Do you have a guess as to if the original bricks on the house made from regional materials? The city i grew up in sits on clay which was used to make the bricks that they built the buildings out of. Beings that they don't make bricks in the region any more it's difficult to get bricks that look similar. As a result any patches or fixes on the buildings are very obvious.

[Tom King]

The guy who laid the bricks on the outside did okay.   The ground there has really sandy topsoil.  I don't think they were used to working with sandy soil.  I've worked on other chimneys where the ground was not sandy, but mostly red clay below a thin topsoil.

Lime was expensive, so it was very typical for them to lay the interior bricks with mud from nearby.  You know how sand sticks together when it's wet, but pours when it dries out.  Red clay works a lot better to lay the interior bricks with, as seen in other chimneys I've worked on.  This has been the first one built with sandy soil for me, and I think probably for the masons that built this chimney too.

They always worked with local stone too.  This sandstone seems really hard, and is the nicest cutting stone I've ever worked with.  It seems like it's harder than it really is though.  The stonework was laid dry, and they used little slivers that accumulated as they were cutting the large stones, to hold the large stones up so the outside face would be flat.  That worked good until the load got to the critical point where the small surface area of the little slivers started to crush.  That let the large stones tilt out.

Another problem is that they dug out a basement after the house was built.  That didn't work too good in the sandy soil either, and the stone walls gradually collapsed into the basement.  Starting to work on that problem, the people who lived in the house in the mid 20th Century started rebuilding the basement walls with pretty decent looking stonework, with Portland cement mortar.  The one wall they did looks pretty good, but it's the wall that chimney sits on the outside of.  The trouble was, they did more undermining of the chimney by digging out enough clearance to lay the new stone wall, but couldn't fill in good under the part of the chimney that they undermined.  The sandy soil from under the outter part of the chimney gradually poured down into the excavated part for the new stone wall.

It's absolutely amazing that the thing is still standing, and I think it is only because the masons did a good job of tying it all together with the Flemish bond, even though the whole interior is soft bricks from the outside of the clump (on site kiln).

[Tom King]

7 minutes ago, Chestnut said:

I'm curious about the bricks. Do you have a guess as to if the original bricks on the house made from regional materials? The city i grew up in sits on clay which was used to make the bricks that they built the buildings out of. Beings that they don't make bricks in the region any more it's difficult to get bricks that look similar. As a result any patches or fixes on the buildings are very obvious.

All bricks were made on site, almost always.  There weren't enough horses in the country to transport many bricks up hills.   Where this house is has red clay subsoil, but it's covered by a pretty thick layer of the sandy topsoil.  It's right on the transition from the Coastal Plain, to the Peidmont.  The Coastal Plain was once the bottom of the sea bed.  Hills start rising right here, and continuously get more elevation all the way to the mountains.

But yes, this is great brick making country.

[Tom King]

Working on the stone chimney base, I've learned a lot about how the foundation needs to be rebuilt.  This picture shows the only surviving part of the original foundation stone work that was still standing.  It was still standing only because there was a perpendicular wall against it inside the basement (see the tenon through the mortise in the treated boards).  When we were replacing these sills, a couple of years ago, I had thought that the stonework looked pretty good.  After learning the real strength of the small rock slivers helping to hold up the large stones, in my work on the chimney base, I have reformulated my plan for the new foundation, and basement walls slightly. 

When preserving such a structure, it needs to look as close as possible to how it did originally, but you run across many things that need a little bit of help with structural integrity for better longevity.

[Tom King]

We didn't make much of a show today, but that's the way this type of work goes sometimes.  Only two small brick parts were laid today.  One piece that shows past the one header brick that had a broken end, but was still holding up the otherwise unsupported row, and one brick half on the corner of one of the corbels.  Both were kind of fragile setting on wet mortar, and I didn't want to disturb them by laying another brick next to them.  The corbel brick bat on the corner was especially fragile, since an inch was left out of two sides of the mortar joints, to be later filled with Lime Mortar, so it had to have a little help holding it up until the mortar sets.  We'll give those over the weekend to set up.

We did fill the cavity behind the newly laid bricks on the previous rows, with soft mixed mortar well packed into all the crevices, and open areas.

Of the unsupported bricks, one header was loose, so I very carefully took that one out, to be replaced in the next session.

The one brick that looks like it's part of the fourth row is really not in that row, but a filler new brick behind where the old brick will go in that row.  

It's good that this house is less than 10 minutes from where I live, so it's not much trouble to go over there, and work just one hour at the time.

[wtnhighlander]

Tedious job, but that's what it takes to do it right, so good on ya!

[Tom King]

We didn't end up laying a brick this morning.  There were some voids back in the hole, from where the bricks fell down that blocked the concrete flow.  Mike mixed some mortar a little bit soft for laying bricks, but stiff enough to stay up when I threw it as hard as I could back in that void.  If we had laid any more bricks, the target hole would have been a lot smaller, and I knew we'd need to rinse the outside off good with the water hose after I got the mortar back in there like I wanted it.

I did decide to grind down the top of that last whole brick to the right on the last row I laid.  I have grinding disks with very large chunks of silicon carbide that eats bricks like they were made from cheese.  I'll show a picture of how it looks tomorrow, when we lay some more bricks.  After the washing with the hose, it was all too wet, which makes bricks too slick to bond to mortar for holding the next layer, but the main objective is to make sure the whole chimney is well supported, so filling that void was the thing to do today.

[Tom King]

We did lay a few more bricks yesterday morning, but it took all night for my cell service to send them from my phone to the computer.  All the face bricks are supported now, except for one little header, but I'm not worried about that one.

It's a lot more to this than just laying the face bricks.  There were lots of voids behind the face bricks, and I wanted to get all of them completely filled to support everything above.  Down to these last two openings now, I have made some ramrods to come close to filling up the holes, and after these last bricks set up, I will ram soft mortar back in there as hard as I can until it just squishes out of the face. Then the last bricks will complete the face.

Using the wet diamond saw, brick hammer, and grinder, I've decreased the height of several courses, rather than taking the loss of height from just one row.  I hope it won't even be that noticeable.  The right side of the chimney lost height relative to the left side as the corbel bricks were crushed as the chimney was leaning.

Lime Mortar will come later.  At first, I had thought that I would just wait until the whole chimney needs to be repointed, but I may go ahead and point these joints up, or most people probably won't understand why this section looks different than the rest.  I have some Lime Putty made up, and we took some of the local sand from a wash in the driveway, so hopefully the new mix will come close to matching the old.

 

[Tom King]

This is on hold, for now.  There is a quarter mile long dirt path to get back in to that house.  When it rains a lot, we try to stay off of it to keep from tearing it up, which requires more work, and money which they don't have.   We've had more than an inch of rain every day since the first storms on Thursday.

Hopefully, it's at a good enough point to be stable for a while.  

It rained heavily again last night, so I doubt we'll get back in there tomorrow.

I'm thinking about replacing that cracked light colored brick above the header that's not replaced yet.  That color tells me it's not one of the harder bricks, and head joints above it aren't looking real promising above it.  I'll wait for all my replaced bricks to set up for some time before taking it out though. 

Those steps of three headers next to each other was not the stronger bond pattern.  They should have made the chimney a half brick wider, but worked themselves into a bind by laying those corbel steps without planning ahead.

[Tom King]

We packed mortar in every crevice back behind the face bricks, and laid the last few bricks for this section, this morning.  At least that part of it is very well supporting what's above it now.   It still needs a lot of work in other sections, but we haven't been paid anything since June, so I will probably let this hold it for a while.