Bulging Rubble Foundation Wall

[jim57]

Trying to evaluate a Rubble Foundation basement wall. The house was constructed in 1850. Wall looks like it was a dugout(stones placed against the earth). Wall was also underpinned. No information on that. Drainage concerns will be eliminated, but would like to provide some type of reinforcement to the wall. Thinking of placing steel soldier beams to the concrete underpinning and floor beams above.

Appreciate any comments or help. Any documents?

 

[JStructsteel]

I would support the structure and excavate out and pour concrete. Dont add a maintenance item to a maintenance item.

 

[Ron247]

Is this an "old mechanical basement" that someone later added a concrete slab and curb to? That is what the pic looks like. It does not look very tall so vertical ( I assume that is what you call soldier) beams should work ok. The right wall looks straight but the left wall looks kind of "bulgy". I would space the columns closer than normal since you have no real continuity in the stones as opposed to masonry block with poured cells.

 

[oldestguy]

I'd remove the worst in sections and build the new wall (concrete) in sections.

 

[geodad]

I once lived in a house that was built circa 1890 and the field stone foundation was at least two feet thick, more in some places. Why do you want to reinforce the wall, are concerned its going to collapse? Are you adding onto the structure or just renovating for sale/occupancy?

Have you investigated the exterior face, does it show the same deflection? Does it sound hollow, is it still moving? Is there any evidence of settlement of the upper floors, are the doors or windows racked, cracks in walls? If none of the above, I would just repoint the stone and maybe paint it, depending on the use of the space.

 

[jim57]

The homeowner indicated that he observed the movement along with water infiltration about 18 months after purchasing the home. Comparing it to photos by the home inspector at time of purchase, movement is new. I first said to start with directing the drainage away from the exterior side to the home. Wall is 16-18" thick and about 6' tall with the soil level at the same height.

 

[BridgeSmith]

That's going to be a tricky one, unless you can find a way to support the structure above without touching the wall. A colleague of mine who saw the picture and I both fear removing even one stone anywhere could result in the whole wall collapsing. I think regardless of the repair strategy, the first step is to shore it. If the opposite wall isn't too far away, you could possibly brace it straight across. If not, maybe you can drive or auger posts to brace to, or dig a trench and brace against the back wall of the trench, or fill the trench with concrete and brace to the concrete.

If you leave some gaps in the shoring wide enough for a post, you can cut out a slot and put in posts or screw jacks to support the structure above while you remove the wall. Another option for that approach is keeping the top of the shoring down far enough to create pockets at the top to run beams through and support the ends on screw jacks inside.

 

[Ron247]

Is the left wall in the picture also the exterior wall of the house?

 

[jim57]

The left wall is also an exterior wall as well as the opposite wall. These walls do not show any signs of distress. The subject wall was receiving water from the terrain up gradient.

 

[Ron247]

How confident are you that hammer drilling the base plate anchors will not cause a collapse due to the vibration? I have no sense of how "delicate" the current condition is. Once you get at least one soldier in, the wall stability gets much better and you can work each direction from there. Problem is, getting the first one in.

 

[BridgeSmith]

I would not be confident doing anything to or near that wall until it's shored up. Vibration or shifting any one of the stones could destabilize the whole thing, burying whoever happens to be in front of it.

 

[Ron247]

I will give the following advice based on having repaired several really bad basements with similar problems but I have NEVER had one that appears this unstable. I have never repaired a stone one that "has a pot-belly worse than mine". I acknowledge in this preliminary design that I am not able to see your actual situation but at least this is a starting point. Not only have I designed several, I have personally installed 3 repairs. The worst one I have repaired I actually bought in bad condition. I could put my hand in the cracks. This is a possible repair that is in need of scrutiny by others.

Absolutely #1-If the weight of the house actually sits on the stone wall, I would do nothing that lifts the weight off the stone wall. Lifting the weight could collapse the wall. If I had to, I could explain why I think this. Your picture looks like the weight of the floor sets directly on the wall. You can support the floor but DO NOT lift it.

#2-Unless the Owner has deep-deep pockets, I would explain that my "possible poor man's solution" is not fool proof and any risk is his, not mine. If they have deep-deep pockets, I would take another avenue. Get it in writing. The problem here is that the wall is unstable and therefore unpredictable. No matter what you choose to do, there could be problems. Even supporting it to remove and replace the wall has risks.

#3- I would not vibrate or do anything that creates a force near the wall. I would start "the collapse distance" away from the wall and work towards it. It would be prudent to install some temporary floor supports away from the wall but again, do not lift the floor. You need to make a safe area to work in general.

#4-Your floor joist are parallel to the wall, so install 1 set of solid blocking between the 2 joists nearest/centered on the stone wall. This should not create any excessive forces. It would be located at the middle of the wall.

#5-Design your column for a 2' on center spacing and attach the top to the block you installed in #4. This should not create any excessive forces.

#6-Place a 16' 4x4 on the floor that bears tight against the column base plate of the "Plumb column"; start 16' from the stone wall and fasten the 4x4 to the floor until you get close enough that the 4x4 can take the axial compression from the base of the wall. Probably about 2,000 lbs or less. You will have to drill partial depth holes in the 4x4 to shoot or drill anchors into the floor.

#7-Add 2 more solid blocks as described in #4 that are inline with the one in #4 that creates a set of 3 joists to resist the lateral top force.

#8-With that in place, do the same 2' on each side of this first column. Basically, add 2 more columns in the same manner as the first one.

#9-Attach the base of column #1 into the concrete with epoxy anchors. Let the epoxy set up for 24 hours.

#10- Drive wood shims between Column #1 and the stone to "preload" the column. Grout the gap between the column and the stone the entire length of the column. Remove the wood shims when the grout cures 24 hours. Remove the 4x4.

#11-install 2 more columns 2' from from the previous ones with the same procedure of steps 4-10

#12-Rinse and Repeat until you have done the entire wall.

 

[bob33]

I like to know what is causing the problem before I proceed with any long-term solutions. This wall was built with lime mortar in 1850. Over time water dissolves the lime leaving behind only sand and voids. Cement-lime mortars became readily available around 1900. The exposed face was probably repointed some time after 1900 using a cement-lime mortar which was much more durable while the interior and earth face mortar continued to dissolve. This resulted in the wall starting to bow. This is a long, slow process. Almost 170 years later, you are essentially dealing with a wall that consists of loose stones.

 

[Ron247]

The possible mortar condition is one reason I say this wall appears more unstable than any I have dealt with. That is a good outline of how the mortar may have progressed over the years. Most defective walls I have seen form a horizontal crack at about eye-level (on an 8' tall wall). The wall then leans inwards from the elevation of that crack so you actually have 2 straight faces that are angled relative to each other. This wall is more a bulge or pot-belly look. That indicates to me the wall is more shifting laterally as compared to cracked and leaning. The worse part of the bulge appears to at a similar location of a traditional leaning wall. The recommendation not to lift the weight off the wall is given more from the leaning wall perspective but I can see where it may apply here also. Lifting the weight off a bulging wall reduces friction which may be holding it at its current location. For the cracked and leaning type wall, in order to collapse more, the width of the horizontal crack has to get wider due to the width of the masonry block. As the wall leans in more, it actually has to get taller due to the rotating width of the wall. Since the wall below the crack cannot go down, the wall above the crack has to raise up. The weight of the house tends to stop this from happening. So at that point, the wall is kinda stuck in position until more lateral force shows up to help lift it more. Reducing the weight in that case could allow more collapse without an increase in lateral force.

 

[hoshang]

This is a possible repair that is in need of scrutiny by others.

Hi
I can't understand the method. Any picture or sketch would be helpful.

 

[hoshang]

I will give the following advice based on having repaired several really bad basements with similar problems

Hi
Is there any sketch of your advice?

 

[StrucDesignPE]

Is this cellar area still in use for mechanical units or storage? If the owner can live without it and the size of the cellar is relatively small, it may be best to fill the whole cellar with a lean mix concrete (flowable fill). This can be done rather inexpensively and quickly. I have done this with several cellar areas that were no longer needed and signs of wall deterioration/failure were present. A small space can be left below the bottom of the floor joists to act as a crawl space for access for mechanical/plumbing/electrical.

 

[Ron247]

I filled a 620 square foot dirt basement with flowable fill. The filling went very smoothly. It was far too dangerous for anyone to work in. A old man hand dug himself a basement that ranged from 7' tall dirt embankment to 10' tall before he quit digging. Then there was a 4' block wall on top of that. Never finished the project but passed away. His wife and daughter hauled all the dirt out in 5 gallon buckets. Over the years, water started seeping in faster and faster. Eventually, some areas had half of the crawl space footing without soil under them.

She was trying to see the house but no one was willing to risk it. This was hands down the cheapest option and could be done without much risk.

 

[hoshang]

Absolutely #1-If the weight of the house actually sits on the stone wall, I would do nothing that lifts the weight off the stone wall. Lifting the weight could collapse the wall. If I had to, I could explain why I think this. Your picture looks like the weight of the floor sets directly on the wall. You can support the floor but DO NOT lift it.

#2-Unless the Owner has deep-deep pockets, I would explain that my "possible poor man's solution" is not fool proof and any risk is his, not mine. If they have deep-deep pockets, I would take another avenue. Get it in writing. The problem here is that the wall is unstable and therefore unpredictable. No matter what you choose to do, there could be problems. Even supporting it to remove and replace the wall has risks.

#3- I would not vibrate or do anything that creates a force near the wall. I would start "the collapse distance" away from the wall and work towards it. It would be prudent to install some temporary floor supports away from the wall but again, do not lift the floor. You need to make a safe area to work in general.

#4-Your floor joist are parallel to the wall, so install 1 set of solid blocking between the 2 joists nearest/centered on the stone wall. This should not create any excessive forces. It would be located at the middle of the wall.

#5-Design your column for a 2' on center spacing and attach the top to the block you installed in #4. This should not create any excessive forces.

#6-Place a 16' 4x4 on the floor that bears tight against the column base plate of the "Plumb column"; start 16' from the stone wall and fasten the 4x4 to the floor until you get close enough that the 4x4 can take the axial compression from the base of the wall. Probably about 2,000 lbs or less. You will have to drill partial depth holes in the 4x4 to shoot or drill anchors into the floor.

#7-Add 2 more solid blocks as described in #4 that are inline with the one in #4 that creates a set of 3 joists to resist the lateral top force.

#8-With that in place, do the same 2' on each side of this first column. Basically, add 2 more columns in the same manner as the first one.

#9-Attach the base of column #1 into the concrete with epoxy anchors. Let the epoxy set up for 24 hours.

#10- Drive wood shims between Column #1 and the stone to "preload" the column. Grout the gap between the column and the stone the entire length of the column. Remove the wood shims when the grout cures 24 hours. Remove the 4x4.

#11-install 2 more columns 2' from from the previous ones with the same procedure of steps 4-10

#12-Rinse and Repeat until you have done the entire wall.

I can't understand the method (especially #4, #5 and #6). Can you attach a sketch?

 

[jim57]

This is what I came up with