Saving leaning 1798 chimney

[Tom King]

This is a house I've worked on periodically over the past 8 or 9 years.  The Charitable Foundation that owns it bought a donor house that I found a while back.  Before I ever started working on it, they had it wrapped in OSB, and housewrap.  Housewrap is designed to last for maybe 6 monthes.  It's been on this house for 10 years, has deteriorated, and was actually holding water in the OSB.  

Since the donor house has siding that is an exact match for the Molded Edge siding on this house, I talked them into letting me take the OSB off, replace the siding that is missing, or needs to be replaced, and paint it.  Hopefully, if it looks better, or maybe shows people what is possible, they may be better able to raise money.

I was planning to wait until the weather is more pleasant this Fall to start working on the outside of it.  In the meantime, this is one of the historic houses that we keep an eye on, and keep the grounds up.  We were there Monday, and I noticed the East Chimney has suffered a problem, and had started a noticeable lean.  While I was still on the tractor, I called a Foundation Board Member, and she said to start on saving it right away.  We did.

First picture shows some of the bricks at the lower right corner had crushed, and exploded away from the chimney.  It has started leaning that way, and it looked like the only thing holding it up was the OSB on that side of it that had way more nails in it than it needed.

We went home, without finishing the grass, loaded up some scaffolding, and went back.  It's rained every day this week a Lot, and we were run off every day before we could get much done other than putting up a couple of sections of scaffolding, and taking some OSB off of the left side of the chimney.  I needed to drill some holes through the big support beams beside the chimney, but didn't want to drill through good siding boards, and the OSB needed to come off anyway.

Long story shortened some, I used long threaded rods, and 4x6's to hold the chimney against the house.  I've done this before, so didn't waste any time trying to decide how to do it.  Pictures should tell the story.  We'll put another tie up higher, but this one pulled the whole thing in to hug the house, so I feel confident it will stay there until next week.   We had good enough weather this morning that we could finish up this stage of it.  We'll need to loosen these ties before we jack it back in place, pour massive footings, and relay the stones and bricks.

Could have been in the What Did You Do Today thread, but thought it might be a little long for that.  This way, I can add the stages we'll do next when we get to them.

 

[Tom King]

A long time ago, Pam stopped asking me what we were going to do today.  She got tired of me saying, "I don't know yet.  We'll do something that needs to be done."

[Tom King]

A few more pictures.  We excavated everything out of the first floor firebox, down to the large stones sitting on the ground.  The base is mostly large stones laid with just dirt, and stones.  The trouble was undermining from when the basement was dug after the house was built.  The inside of the chimney bottom is not gutted down to what stones are actually holding weight.

Two of the main supporting stones, are leaning severely outward, but are still holding the leaning side of the chimney up.  I changed plans about three times the day I was digging out that part under the firebox.  Now the plan is to get some 1" steel plates as large as will fit, and using forty ton jacks, ease up the dropped side of the chimney, push the leaning large stones back in place, and unitize the whole bottom of the chimney by filling the excavated part with concrete. 

All the remaining stonework in there is irregular enough that it should bond fine with the concrete.  Once it's unitized, we can excavate under the lower part, pour a massive footing, and do some more jacking.  It's about 6" out of plumb right now. 

I know it's hard to tell much from the phone picture of the inside, but you can see some daylight coming into the corner between the two large, leaning stones.  I'll try to think to get a picture of that tomorrow.  That one long rectanglish stone in front of the daylight is mostly loose.  It will come out, and the jacks will set right outside of where that is-good bricks above to support weight.  I'm going to make long jack handles so people manning jacks can stand out of harms way.  It's still possible that the whole thing might come down.

The first step down you see past the wood floor is the foundation wall, that was stonework redone in the mid 20th Century.  I'm going to have to build a smooth partition on the chimney side of that so that we can move the chimney after the concrete is poured.  Some leftover roofing metal will be again the smooth wall, but not fastened, so the chimney can slide without being in a bind against the stone foundation wall.

The upper 4x6 holding the chimney to the house has a backup 4x6 on the inside wall that extends to, and is tied to the corner post. I'll try to think to get a picture of that tomorrow too.

A while back, a retired engineer in the Foundation that owns this house asked me what I called this type of planning.   I told him I call it "Eyeball Engineering".

I got so dirty digging that base out that I went home and took a shower, and changed clothes before we went to lunch, then did the same thing again when I came home for the day.  Plus my legs were so tired from squatting, and getting up and down, that it felt like I had been doing barbell squats all day-not really bad today though.

 

[Chestnut]

I'd love to work on your crew for a few weeks. The projects you get to work on are so interesting, hard work, but interesting.

[Tom King]

Not much of a crew.  These days, just me, and Big Mike.

[Tom King]

A few more pics I took with the good camera today.  It's in a very precarious state.  The plan is to jack the dropped side of the chimney enough to push those big stones back in place, and massive reinforcement to fill the whole base with concrete.  All those stones you can see down below the first floor firebox are the only ones left supporting weight, and are jagged enough to get a good grip on the mass of concrete, which should unitize the whole bottom of the chimney.

If that is successful, the next steps will be more excavations under the concrete, pour more massive footings, and more jacking.  Like I've done before, we'll end up leaving a number of large jacks in a big mass of concrete.......if it all doesn't fall down somewhere in this process.

I finally got a Foundation Board Member out today to see in person what's going on, what I'm doing, and she agreed that it had to be done.

[drzaius]

2 hours ago, Tom King said:

Like I've done before, we'll end up leaving a number of large jacks in a big mass of concrete......

That'll make for an interesting archeological dig one day.

[Chestnut]

On 7/3/2019 at 5:57 PM, drzaius said:

That'll make for an interesting archeological dig one day.

Just like all those excavators underneath the wealthy London homes from rich people that wanted to expand their basements.

It makes sense to just encase the jack. Is there any chance of it rusting out and creating a weak spot? Probably not as rebar doesn't usually do this, but there is a reason the stuff under highways is epoxy coated.

[Tom King]

There were six 25 ton hydraulic bottle jacks, and a 10" I-beam left in this pour.   There is plenty of cubic yardage of concrete under it for the metal not to be a worry.  It was just sitting on top of the ground when they built it.

[Tom King]

We also had to shove that one several inches back to the house. It's 43 feet tall. This is after that concrete pour.  As soon as we jacked it into position, I called for the concrete truck, and we built the form while we waited for the truck to get there.  After the concrete cured, and we pulled the form off, the Bituthene over the Bentonite clay panels was carried up over the concrete to ground level.  There is a big mass of concrete under that last pour, that we did the jacking off of.

Those are actually two different chimneys, on opposite ends of the same house.  You can tell by looking at the stonework.

[Tom King]

That last house belongs to a friend of mine.  It's on their family land, and his Mother always dreamed of restoring that 1828 house.  He said it took him 30 years to think about doing something about those chimneys, 30 days to meet with two chimney experts, and 30 seconds after meeting with the last one to decide to tell me to "just do it however I saw fit", because the experts wanted $30,00 in advance because if they dropped the chimney out into the yard, he wouldn't want to pay them.  We did both chimneys for about half of that.

I had never done anything with moving a chimney before.  The owner works for NASA, and says that their definition of an "expert" is someone who has done something once before.  I guess that makes me an expert after doing those chimneys on that first house, but I'm still worried about losing this older, more fragile one.

[Tom King]

Today, we were able to get the big stone back in place, and in the process, get the supporting vector above it into a much more stable line. I used an old blade in a cordless reciprocating saw (Sawzall), to cut some clearance between the small rock, and the large one.  Each cut allowed us to move the big stone in a little bit.  Some extra persuasion was provided by a 20 lb. sledge hammer.

You might be able to see the difference in the level of the small stone in the starting, and ending photos.  The bricks above the small stone, in that leaning corbel, are now in a much more stable level.  We can't get it all back because the softer internal bricks have crumbled, and taken up space, so we're going to leave it here. 

The right end, as seen in earlier pictures, which is supporting a major amount of weight will be left where it is.  That part won't be seen anyway because of a porch that will need to be replaced around that chimney.

We're trying to round up a water pump to use in the well with a generator, so I can wash down everything inside the bottom of the chimney, including this large stone, so it can bond with the concrete.

I was thinking I needed to build a movable partition between the foundation wall, and the mass of concrete, so we can move the chimney independent of the foundation wall, after the base is unitized with concrete.  Today, after we got the big stone back in place, I decided to go back inside, and look at the inside of the base again, and it came to me that I could just stack sand bags in there to serve as the release partition.   I can't plan this stuff out in advance.  My plan changes every day, and sometimes several times a day.

As you can see by the spacers we had to stick between the stake in the ground, and the first 12' 4x6 prop that we started with, we moved it in three inches, plus some taken up by the wedges, so maybe as much as four inches.

Tomorrow we'll lay some stones to fill up open spaces, so the concrete won't run out, and make a mess, and set some more props, and forms so the concrete  can't push anything out.  It will be about 3' high inside the bottom of the chimney.

[Tom King]

This past week, we worked on it as much as we could in the mornings, starting early, but it's on the East side of the house, and in this extreme heat wave, we can only work on the outside until about 9:30, before it becomes completely unbearable.

This house is about 1/4 mile off the highway, and has no electricity.  There is a modern, shallow well that's 32 feet deep with 13 feet of water in it.  I bought a little self=contained shallow well pump/tank, and controls from Harbor Freight.  That little thing surprised me, and it ran 4 hours WFO yesterday, with almost as much pressure, and volume of water as you might be used to at home.

The plan was to wash the dirt off the supporting stones in the base of the chimney.  It worked better than I even expected.  Not only did it clean the stones off nicely, so that concrete can bond to them, but it allowed me to get out a lot more of the smaller stones that weren't really holding anything up, but were jambed in place with the dirt "mortar".   This was maybe the most dangerous game of Jenga ever.

I was able to get clear paths out to daylight all around the chimney for concrete to flow to, and take over the supporting role.

That large stone, seen earlier in the thread, is back in its original position.   I was able to wash the dirt, and soft brick particles, that had fallen down behind it, out of the way, so it could go all the way back in.

We're building a pretty massive structure around the outside of the stone base to hold the 3 to 4 foot height of concrete inside.  Sandbags will be stacked on edge against the stone foundation wall, to act as a release barrier, so the chimney can be jacked back in place independent of the foundation wall.

 

[Coop]

Tom, I’m glad you know what you’re doing. To me, this just looks like a pile of odd size rocks and bricks. Good luck bud! 

[Tom King]

It has nothing at all to do with knowing what I'm doing.  It's one hundred percent figuring it out as I go along.  There is still a chance that the whole thing will tumble down.

[Chestnut]

I doubt that it will come falling down. It appears that, if you don't know what you're doing, are good at making things work on the fly. I do hope that if anything catastrophic does happen that no one gets injured or worse.

This is very interesting to follow

[Tom King]

It's seriously in a precarious state, and is indeed in danger of losing the whole thing.   When it was built, concrete hadn't been invented yet, so the mortar is Lime Mortar, which is really nothing but Lime, and Sand.   It does not have anything like the adhesive strength of what we know as mortar today.  It does get stronger, as Centuries pass, and the Lime tries to turn into Limestone by absorbing carbon dioxide out of the air, but being just 223 years old, it's nowhere near maximum strength yet.  Long story short, no brick in this chimney is secure without support from underneath.

I'm not worried about any of the firebox collapsing.   I can rebuild that, and will have little effect on the final result for the whole chimney.   I can rebuild the whole chimney, if needed, but I'm running out of working years, and they would never be able to raise enough money anyway.   Preservation is saving what's there, with as little changing as possible.

I you look at the last picture, the stone with a whitish top, in the center of the picture, is the key for that whole side staying up.   A new stone wall was laid in the middle of the 20th Century with Portland Cement Mortar to replace that basement wall.  That wall is seen next to the floor.  They undermined the chimney when digging out enough room to build the wall, and that's why we have this problem now.

On the left end of that stone, what you see draped over it is some of that concrete mortar.   If that mortar wasn't there, I think that stone would move enough to become a catastrophic event. It needs to be a breakaway point in order to jack the chimney after the mass of concrete is poured.  Sandbags will be stacked on edge against that stone wall, so the chimney can move independent of that wall, but still letting that piece of mortar break.  If the wall cracks, it won't be anything catastrophic, but I think we might get lucky, and save both.

My reputation could go either way with this.

Tomorrow, we will need to take down the scaffolding on the outside back of the chimney, but leave the stack on the side.  Then the joints between the stones will need to be pointed with mortar, and smaller stones.   After that, the massive wooden structure around the base needs to be finished, the sandbags stacked, and then we'll be ready to pour concrete.  It all wouldn't have been so bad, if we weren't in this worse heat spell in recorded history, and our days being cut short because of it.

Also, we ended up working all day today, in this heat, saving a porch on a house I built 30 years ago, that a tornado hit this past week.  It will end up being fine, but we're both worn out to start the week tomorrow, and that house will have to wait like we stabilized it today, until we get this chimney stabilized (hopefully).

 

[Tom King]

Rained out yesterday, but we got back to it today.  The day before, we had taken down the scaffolding on the face of the chimney, to make room for the concrete truck, and stacked the sand bags inside against the stone foundation wall.

Today, after all the washing out with the water hose, I was able to get the large stones, seen earlier in  this thread, all the way back into their original position.  New props were set against the outter ends of the large stone, to allow space for a concrete truck to back in close.

The original stonework was laid dry, but we're going to have to soften up the concrete, so it can flow into all the small spaces, so it needed to be pointed up with mortar.  This part will eventually be covered by a porch floor, so it won't be easily seen anyway. It will be seen for a good while though, so I did clean my joints up.  If we had more time for it to set up, I would have used Lime Mortar, but being on borrowed time anyway, I went ahead and used modern mortar.

We'll let this mortar set up until tomorrow morning, and so tomorrow's job will be to build the massive wooden framework around the stonework, so it can't spread from the pressure of the 3 foot tall mass of concrete.  I think it will take almost two yards.  Minimum order is three yards anyway, so I'll just get them to bring three yards.  I have a good spot for any leftover.

This local Sandstone is plenty dense enough, but the easiest to cut like I want, that I have ever worked with.

Normally, I don't lay old brick with Portland Cement Mortar, but I laid those few high fired bricks that you see on top of the large stone in a bed of it because I want the concrete to go to the level of the tops of those bricks.  The bricks to the left have crumbled to the point that we'll take them out, and replace later, but I think they're secure enough to hold the concrete back.

 

[Tom King]

In the next to last picture, look up under the row of dark bricks (good hard high fired, and you can see the remnants of one dark brick.  That one brick remnant is holding up the whole row above it, and a pyramid shaped group above too.  It would have lost a lot more bricks if that hard brick part wasn't still there.

The five bricks in a row, on top of the large stone, are the ones I laid today.  They're all whole bricks, and very irregular on their bottoms.  Half of the brick lengths protrude into the void behind the large stone that will get filled with concrete.  Those whole bricks should bond to the concrete, and make the whole structure above them much more secure than its ever been. 

The thing sitting on top of the second from the left, of the five bricks, is a stone to keep it from tipping back until the mortar sets.

I tried to get the part I pointed to look fairly close to the original stonework that didn't have any mortar in the joints.  I put those small stones in place in the joints.  When we lay the stonework for the new basement, if they ever raise enough money, I'll use mortar similar to this, but it will not come out anything like this close to the surface, so hopefully, it will look closer to the original.

That stone with the white stuff on it was originally tight against the end of the large stone.  It tipped out, and caused the chain reaction that made the chimney lean.   There just happened to be a very large stone, sitting right beside it, that temporarily prevented it from falling all the way to the ground.  We picked that large stone (the one on the ground doing the holding) out of the yard, and put it back in there "to get it out of the way", some years ago when we were doing the grading for waterproofing the basement that had standing water in it.

[Tom King]

Concrete pour scheduled for Friday morning at 8:30.  We have a massive wooden structure around the stonework built out of 2x12's bolted together, with 4x's bolted to them, and held in place by stakes driven in the ground.  All stones are wedged against the 2x12's.  Hard to know how much is enough because we're going to need to run a vibrator down in the concrete to make sure it moves into all the small recesses.

It dropped some on the right side from Friday, to Saturday.  It wouldn't have been noticeable, but I screwed a couple of 2x4's to the 4x6 clamps when we took the face scaffolding down to be able to build the "form", and allow access for a concrete truck.  Those screws were broken when I gave a tour Saturday morning.  One more critical supporting brick had crushed.  Those 2x4's are to hold the clamp 4x's up to keep them from dropping, and binding when they are loosened when we jack the chimney back up.

Access is down a dirt path for a quarter mile back in the woods.   We've had enough rain lately that we had to wait for it to dry out enough to get a concrete truck back in there, and also work with their scheduling.

News teams expected to be there.  It's either going to be an award winner, or a colossal failure.

 

[Coop]

Wishing you the best of luck tomorrow Tom! 

[Tpt life]

It’s go time!!!!!!

[Tpt life]

Concrete go ok @Tom King?

[drzaius]

1 hour ago, Tpt life said:

Concrete go ok @Tom King?

I hope he's not still at the site.

[treeslayer]

I hope he’s at a bar celebrating