I’m wonder if you can help. A little background… I live in Canada, Edmonton, Alberta to be exact. My house was built in an area that had a lot of muskeg, which is comprised of mosses, sedges, grasses, and remnants of plant matter decomposed to various extent. Long story short it’s a nightmare to build on. In my area, I believe they excavated away the muskeg which left a lot clay based soil. We also have a high water table, so most homes are built with a sump pump system. I have a hilled backyard, so water drainage flows through the front grass and a rock swale on the other side. My neighbour and I both have downspouts at the front and back of our houses that drain into the rock swale. The driveway was mudjacked about 15 years ago. While there has been some settlement, it was minor and no new cracks had formed on the surface or in the expansion joints. Just over 2 years ago, a cable company decided upgrade to fibre optic cable. They contracted another company to do the work, which involved drilling channels underground along the utility easement area by the sidewalk of everyone’s property and underneath our driveways. They also installed a 36 x 24.4 inch service box in the rock swale on the North side of my driveway by the sidewalk. Not one employee from either company knew what fluffing or the expansion factor was. There was no engineering assessments prior to the work. They started the work in early November when the ground was already frozen and temperatures were below freezing. Immediately before digging the hole in the rock swale, they flooded the soil and for some reason removed soil from underneath my driveway; undermining the integrity of the foundation. I discovered this when part of my driveway fell into the hole. The excavated hole was left uncovered for several days during a heavy snowfall, before the service box was finally installed. They didn’t completely backfill all the dirt because they ran out of supplies and had to wait until spring to finish the work. A 4” channel was also left open spanning the driveway parallel to the sidewalk. That winter my driveway did not do the normal frost heaving, it settled lower then ever before. Apparently the frost heaving was extremely bad that year, because of periods of unusually warm weather, melting snow and rain, followed by extremely cold weather in the -30°c. In the spring, water from melting snow couldn’t drain properly, because the water was blocked by piles of soil and rocks they left in the rock swale. Water pooled in the area between the houses, which had NEVER occurred before (my neighbour is the original owner and I’ve lived here for 17+ years.) Unfortunately my property is lower than my neighbour’s so as you said, the path of least resistance was under my driveway. No concrete products were used during the partial or final backfilling process, so the integrity of the driveway foundation wasn’t repaired. When they completed installing the cables in the spring, they just levelled out the piles of soil and rocks, which damaged the landscaping grade and caused more drainage problems. Water no longer flows towards the street, it stays in the area where the downspouts are, which is right next to the separation joint of the garage. Even though we had frost heaving prior to this work, there was no “stepping” of the driveway away from the garage foundation until after the work was done. Prior to the work my driveway would heave up and be level with the garage floor in winter and then slowly settle back about 1-2” over the spring/summer. After the work a gap formed in the separation space between the driveway and garage foundation and has continued to widen, and parts of fibreboard have just disappeared. What’s odd, is that the normal frost heaving and settling cycle has essentially stopped. In fact parts of the driveway by the sidewalk settle lower during the cold winter months. My driveway is now approximately 2 inches lower by the sidewalk and 3-4 inches at the garage. The driveway is sloped so water is damming at the sidewalk. This part of the driveway has never been mudjacked, because it didn’t move. The expansion joints also cracked and widened after the work. The center of the driveway is now uneven; the North side is about an inch higher then the south side. The middle portion on the North side of the driveway has dropped lower then the rest of the driveway, which is where the piles of rocks and dirt were placed. Luckily I had hired several really bad snow removal companies, so I had a lot of photos of my driveway before the work. After 2 yrs I finally got the company to admit fault, but they don’t want to admit to everything. The engineer they hired blamed normal frost heaving cycles for the settlement and “stepping” by the garage, even though that has essentially stopped and this is where the water accumulates. Unfortunately it seems the company is trying to do the minimum to fix it. They just want to mudjack the driveway by the sidewalk, and fix the grade in the rock swale. I learned a lot in your video, but I want to have a better understanding of my situation so I can hire the proper engineer or professional for this situation. First question: would the expansive properties of the clay based soil cause soil migration or worsen any voids caused during excavation, leaving open spaces for several months or improperly backfilling? Would any of this affect the compaction of the soil underneath the driveway? Can soil migration occur when the integrity of the foundation was damaged? Would 2 years of improper drainage cause enough soil erosion to create voids large enough for the fibre board to fall into? Is there a way to check the soundness of the driveway foundation? Do you have ANY other recommendations? Any help would be very appreciated.
Whoo. You have quite the history and question! It's difficult to analyze something without physically looking at it or testing soil rpoperties, so there's a lot of assumptions I would need to make to adequately reply to all of your concerns. I'd have to caution you both that I'm not a lawyer, nor a registered engineer, I am just a guy trying to provide helpful info based on the knowledge and experience that I DO have. That being said, the following: 1) Yes, it CAN migrate soil or worsen voidspace between particles, but it can have the opposite affect as well. This is why gound preparation is so important, to control some of that chaos. But like a slab that settles that needs to be sawcut to prevent aggregate lock before lifting it back up - thing's don't rise and fall in perfect harmony. Like any remodeler who understands there's no such thing as straight, level, and plumb on the easiest of jobs =) 2) Depending on the type of clay, it can affect the compaction levels more or less severely. A hard clay or caliche clay is still incredibly strong in its expanded state, even lifitng entire structures instead of just slabs. But the mass itself doesn't just disappear when it expands or constricts, it simply puts water into the particles and creates expansion. The compressive strength would be affected, then, but in many ways based on soil type. 3) If you create a void, soil can move into the void. Things have the tendency to be lazy, succumbing to gravity first, and the easiest paths of resistance second. Now if the soil isn't collapsible or loose, it will have the tendency to tie together and you have less risk of the soil migrating at all, which is why many clays will remain in place while moving the things on top it (staistepping, like slabs). 4) Regarding the erosion question of two years, it's a tough one. Yes it can, couldn't possibly tell you if that's something you're at risk of or if that's happening at your residence. There's far too many factors from soil type to level of moisture to rate of movement of the moisture to gradient to many other things, it's just not something I can say is happening at your residence, and would defer to specialist on that one. 5) I would defer more to a structural engineer to check the soundness of something, but there are tests that can be done for the strength of concrete. 6) Realistically, it may seem like their problems have exacerbate the issues at the home, but it doesn't necessarily make them the CAUSE of the problem. I would ensure they mudjack under the driveway and fix the rock swale, for sure. There was some negligence exercised and it should be corrected (my opinion, not a legal opinion). But soils properties do change over time. It would be very difficult to put that one the cable company as long as correllation is not causation. I'd put some nasty letters in there too hah. 7) With the parameters you offered, remember that organic material will decompose over long periods of time. This may put off gasses or just as importantly create pocket voids and weaker layers of soil that will allow subsidence around the property. It's why we do a lot of treatments for areas built over former landfills. A critical part of stability will be to control the moisture around the property, and ESPECIALLY under heavy structures like your home. For lighter structures, it is ever the challenge to maintain levelness and stability. People throughout areas of Southern California have pretty much accepted cracking sidewalks and even driveways as life. Expansion joints will always help, but expansive soils will always behave as they do. I know not the best evaluation or what you were hoping to hear, but those are my thoughts as best as I can gather them. I hope this helps you to understand and, if I am in error, please feel free to share!!!!
Thank you I'll get the engineer out to my lot before I start I see it's caly as when it was dry lots of cracks in the ground and I don't know how deep it goes but it is on a slope putting a 16 x 80 custom single wide mobile before I put the footings in North Carolina
Thanks for the great video, how about using a corrugated metal sheets around the building to act as a concrete curtain? then import mixed soil/gravel to fill the excavation between the metal sheets and the foundations. As for the interior slab, you may drill wills every 500sq-ft to drain excess moisture from the soil beneath the slab.
Did some checking around with a few of the Civils I work with, and this solution checks out! Depending ont he existing condition of the expansive clay (how expanded it is at the time of repair), the dissolution of water may result in some anticipated settlement, but then again if the issue is a heave caused by expansion then you can expect the structure to settle back to within normal parameters, assuming the initial construction was done properly. Any and all efforts to utilize drainage the mitigate the expansion and constriction can only be a benefit. Thanks for sending me toward a different means of mitigation!
That will vary on the issues you're experiencing and the site conditions for your specific problem. In example, if you're on a hillside and you're experiencing some of the problems laid out in our hillside video, then you would want to do an evaluation of the slope, finding the slip plane, and perhaps a slope stability analysis that includes some testing with an inclinometer. That's ENTIRELY unnecessary on a flat lot ina flat subdivision. With that out of the way, generally you will want either a "Ground Improvement Report" or a "Soils Report" from a Civil or Geotechnical Engineer. The report will include some soils testing which, at its most basic, will tell you the soil type, gradation, moisture content, dry density, plasticity index, expansion index, and record the N values for the relative strength of the soil. In addition, there should be observations of the site conditions, and repair recommendations if necessary. More comprehensive reports (typical of soils reports and required by CBC/IBC) will also include int he evaluation the seismic design category and how that affects the property, and an evaluation of available information through the local jurisdiction with regard to historical landslide/flooding/etc zones in the area. When you consider it all, there's a reason those soils reports get to be so expensive! If you move into the permitting phase, depending on local municipal codes, many cities now also require historical reviews which are MUCH more detailed plans and reports, and require a TON more effort (and cost).
A separation crack, where the wall is pulling apart, assuming it is not a bonding related crack, or other minor type of cosmetic crack, indicates that the wall is being pulled apart, specifically. This could mean that another portion of the foundation is settling down, which pulls upward on the SuperStructure, and creates the separation where you are seeing, this type of crack, or it could mean that the foundation underneath that crack is pulling down and out, creating that type of separation. Inversely, if the crack is “pushing out” the drywall instead of separating it, it indicates that there is a type of compression going on. This could mean another portion of the foundation is lifting upward, which would push down on the super structure, and create a compression, tape, crack, or the foundation underneath that crack could be pushing upward, also creating a compression. In addition, it could indicate that the loading of the structure is greater than what structure can support, and it is collapsing in the wall, and creating a compression tape crack, which would be indicated by a perfectly level foundation, or more stress fractures on the slab, pushing down, if the slab is going down as well. In any case, the compression tape cracks indicate some very specific failures, and usually are not related to differential settlement. Some exceptions, of course, could always apply.
That is definitely the conundrum. On one hand, it’s something that cannot positively be done with absolute certainty without an engineers input. On the flipside, you can spend $80,000 doing soils testing on a single property, and still not know exactly what the soils are, and how to mitigate them. Civil engineering is the most inexact form of engineering that exists. For that reason, there will always be an associated risk. So you have to find the balance between the testing of the soil and value engineering. That being said, everything in San Francisco is expensive 😂😂😂 There are some good foundation repair experts in the area. Many of them use combinations of systems, or they specialize in a single system, such as piering, concrete replacement, drainage mitigation, or polymer injection. Notable companies in the bay area are URETEK, FRC, bay area underpinning, Ramjack, and EagleLIFT. When these companies provide recommendations, it should be backed by an engineers analysis. Some companies opt to use engineers to create plans and reports based off of their findings, without doing an on-site investigation. This can work, but it’s sometimes very difficult and it’s a good standard of practice to have the engineer actually be on site and evaluating the issues. From that point forward, depending on the repair type, either repair specific or site specific soils testing and analysis should be a bare minimum. In example, I could do a soils test to evaluate how deep a push pier would go, but that would only be part of the information needed for a helical pier. That would also provide good information on how deep polymer injection would need to be provided, but it would not provide soils type, which could change the type of polymer, or render the polymer ineffective, if the soil was not porous enough for the polymer to travel. So this is probably just the long-winded way of saying there is value engineering available, but it will still be expensive, and it is always necessary.
The yt algo seems to work this time. Got your video recommended and your presentation style fits my learning style.
Thanks mate! Appreciate the comments!
I’m wonder if you can help. A little background… I live in Canada, Edmonton, Alberta to be exact. My house was built in an area that had a lot of muskeg, which is comprised of mosses, sedges, grasses, and remnants of plant matter decomposed to various extent. Long story short it’s a nightmare to build on. In my area, I believe they excavated away the muskeg which left a lot clay based soil. We also have a high water table, so most homes are built with a sump pump system. I have a hilled backyard, so water drainage flows through the front grass and a rock swale on the other side. My neighbour and I both have downspouts at the front and back of our houses that drain into the rock swale. The driveway was mudjacked about 15 years ago. While there has been some settlement, it was minor and no new cracks had formed on the surface or in the expansion joints.
Just over 2 years ago, a cable company decided upgrade to fibre optic cable. They contracted another company to do the work, which involved drilling channels underground along the utility easement area by the sidewalk of everyone’s property and underneath our driveways. They also installed a 36 x 24.4 inch service box in the rock swale on the North side of my driveway by the sidewalk. Not one employee from either company knew what fluffing or the expansion factor was. There was no engineering assessments prior to the work. They started the work in early November when the ground was already frozen and temperatures were below freezing. Immediately before digging the hole in the rock swale, they flooded the soil and for some reason removed soil from underneath my driveway; undermining the integrity of the foundation. I discovered this when part of my driveway fell into the hole. The excavated hole was left uncovered for several days during a heavy snowfall, before the service box was finally installed. They didn’t completely backfill all the dirt because they ran out of supplies and had to wait until spring to finish the work. A 4” channel was also left open spanning the driveway parallel to the sidewalk. That winter my driveway did not do the normal frost heaving, it settled lower then ever before. Apparently the frost heaving was extremely bad that year, because of periods of unusually warm weather, melting snow and rain, followed by extremely cold weather in the -30°c. In the spring, water from melting snow couldn’t drain properly, because the water was blocked by piles of soil and rocks they left in the rock swale. Water pooled in the area between the houses, which had NEVER occurred before (my neighbour is the original owner and I’ve lived here for 17+ years.) Unfortunately my property is lower than my neighbour’s so as you said, the path of least resistance was under my driveway. No concrete products were used during the partial or final backfilling process, so the integrity of the driveway foundation wasn’t repaired. When they completed installing the cables in the spring, they just levelled out the piles of soil and rocks, which damaged the landscaping grade and caused more drainage problems. Water no longer flows towards the street, it stays in the area where the downspouts are, which is right next to the separation joint of the garage. Even though we had frost heaving prior to this work, there was no “stepping” of the driveway away from the garage foundation until after the work was done. Prior to the work my driveway would heave up and be level with the garage floor in winter and then slowly settle back about 1-2” over the spring/summer. After the work a gap formed in the separation space between the driveway and garage foundation and has continued to widen, and parts of fibreboard have just disappeared. What’s odd, is that the normal frost heaving and settling cycle has essentially stopped. In fact parts of the driveway by the sidewalk settle lower during the cold winter months. My driveway is now approximately 2 inches lower by the sidewalk and 3-4 inches at the garage. The driveway is sloped so water is damming at the sidewalk. This part of the driveway has never been mudjacked, because it didn’t move. The expansion joints also cracked and widened after the work. The center of the driveway is now uneven; the North side is about an inch higher then the south side. The middle portion on the North side of the driveway has dropped lower then the rest of the driveway, which is where the piles of rocks and dirt were placed.
Luckily I had hired several really bad snow removal companies, so I had a lot of photos of my driveway before the work. After 2 yrs I finally got the company to admit fault, but they don’t want to admit to everything. The engineer they hired blamed normal frost heaving cycles for the settlement and “stepping” by the garage, even though that has essentially stopped and this is where the water accumulates. Unfortunately it seems the company is trying to do the minimum to fix it. They just want to mudjack the driveway by the sidewalk, and fix the grade in the rock swale.
I learned a lot in your video, but I want to have a better understanding of my situation so I can hire the proper engineer or professional for this situation. First question: would the expansive properties of the clay based soil cause soil migration or worsen any voids caused during excavation, leaving open spaces for several months or improperly backfilling? Would any of this affect the compaction of the soil underneath the driveway? Can soil migration occur when the integrity of the foundation was damaged? Would 2 years of improper drainage cause enough soil erosion to create voids large enough for the fibre board to fall into? Is there a way to check the soundness of the driveway foundation? Do you have ANY other recommendations? Any help would be very appreciated.
Whoo. You have quite the history and question! It's difficult to analyze something without physically looking at it or testing soil rpoperties, so there's a lot of assumptions I would need to make to adequately reply to all of your concerns. I'd have to caution you both that I'm not a lawyer, nor a registered engineer, I am just a guy trying to provide helpful info based on the knowledge and experience that I DO have. That being said, the following:
1) Yes, it CAN migrate soil or worsen voidspace between particles, but it can have the opposite affect as well. This is why gound preparation is so important, to control some of that chaos. But like a slab that settles that needs to be sawcut to prevent aggregate lock before lifting it back up - thing's don't rise and fall in perfect harmony. Like any remodeler who understands there's no such thing as straight, level, and plumb on the easiest of jobs =)
2) Depending on the type of clay, it can affect the compaction levels more or less severely. A hard clay or caliche clay is still incredibly strong in its expanded state, even lifitng entire structures instead of just slabs. But the mass itself doesn't just disappear when it expands or constricts, it simply puts water into the particles and creates expansion. The compressive strength would be affected, then, but in many ways based on soil type.
3) If you create a void, soil can move into the void. Things have the tendency to be lazy, succumbing to gravity first, and the easiest paths of resistance second. Now if the soil isn't collapsible or loose, it will have the tendency to tie together and you have less risk of the soil migrating at all, which is why many clays will remain in place while moving the things on top it (staistepping, like slabs).
4) Regarding the erosion question of two years, it's a tough one. Yes it can, couldn't possibly tell you if that's something you're at risk of or if that's happening at your residence. There's far too many factors from soil type to level of moisture to rate of movement of the moisture to gradient to many other things, it's just not something I can say is happening at your residence, and would defer to specialist on that one.
5) I would defer more to a structural engineer to check the soundness of something, but there are tests that can be done for the strength of concrete.
6) Realistically, it may seem like their problems have exacerbate the issues at the home, but it doesn't necessarily make them the CAUSE of the problem. I would ensure they mudjack under the driveway and fix the rock swale, for sure. There was some negligence exercised and it should be corrected (my opinion, not a legal opinion). But soils properties do change over time. It would be very difficult to put that one the cable company as long as correllation is not causation. I'd put some nasty letters in there too hah.
7) With the parameters you offered, remember that organic material will decompose over long periods of time. This may put off gasses or just as importantly create pocket voids and weaker layers of soil that will allow subsidence around the property. It's why we do a lot of treatments for areas built over former landfills. A critical part of stability will be to control the moisture around the property, and ESPECIALLY under heavy structures like your home. For lighter structures, it is ever the challenge to maintain levelness and stability. People throughout areas of Southern California have pretty much accepted cracking sidewalks and even driveways as life. Expansion joints will always help, but expansive soils will always behave as they do.
I know not the best evaluation or what you were hoping to hear, but those are my thoughts as best as I can gather them. I hope this helps you to understand and, if I am in error, please feel free to share!!!!
Thank you for the video. I have learned a lot.
Thank you I'll get the engineer out to my lot before I start I see it's caly as when it was dry lots of cracks in the ground and I don't know how deep it goes but it is on a slope putting a 16 x 80 custom single wide mobile before I put the footings in North Carolina
Thanks. Very helpful.
Thanks for the great video, how about using a corrugated metal sheets around the building to act as a concrete curtain? then import mixed soil/gravel to fill the excavation between the metal sheets and the foundations. As for the interior slab, you may drill wills every 500sq-ft to drain excess moisture from the soil beneath the slab.
Did some checking around with a few of the Civils I work with, and this solution checks out! Depending ont he existing condition of the expansive clay (how expanded it is at the time of repair), the dissolution of water may result in some anticipated settlement, but then again if the issue is a heave caused by expansion then you can expect the structure to settle back to within normal parameters, assuming the initial construction was done properly. Any and all efforts to utilize drainage the mitigate the expansion and constriction can only be a benefit. Thanks for sending me toward a different means of mitigation!
Thanks for great video so what kind of report we should get from a soil inspection engineer ?
That will vary on the issues you're experiencing and the site conditions for your specific problem. In example, if you're on a hillside and you're experiencing some of the problems laid out in our hillside video, then you would want to do an evaluation of the slope, finding the slip plane, and perhaps a slope stability analysis that includes some testing with an inclinometer. That's ENTIRELY unnecessary on a flat lot ina flat subdivision.
With that out of the way, generally you will want either a "Ground Improvement Report" or a "Soils Report" from a Civil or Geotechnical Engineer. The report will include some soils testing which, at its most basic, will tell you the soil type, gradation, moisture content, dry density, plasticity index, expansion index, and record the N values for the relative strength of the soil. In addition, there should be observations of the site conditions, and repair recommendations if necessary. More comprehensive reports (typical of soils reports and required by CBC/IBC) will also include int he evaluation the seismic design category and how that affects the property, and an evaluation of available information through the local jurisdiction with regard to historical landslide/flooding/etc zones in the area.
When you consider it all, there's a reason those soils reports get to be so expensive! If you move into the permitting phase, depending on local municipal codes, many cities now also require historical reviews which are MUCH more detailed plans and reports, and require a TON more effort (and cost).
what is the significance of wall cracks where it isnt separation but pushing in? 6:01
A separation crack, where the wall is pulling apart, assuming it is not a bonding related crack, or other minor type of cosmetic crack, indicates that the wall is being pulled apart, specifically. This could mean that another portion of the foundation is settling down, which pulls upward on the SuperStructure, and creates the separation where you are seeing, this type of crack, or it could mean that the foundation underneath that crack is pulling down and out, creating that type of separation.
Inversely, if the crack is “pushing out” the drywall instead of separating it, it indicates that there is a type of compression going on. This could mean another portion of the foundation is lifting upward, which would push down on the super structure, and create a compression, tape, crack, or the foundation underneath that crack could be pushing upward, also creating a compression. In addition, it could indicate that the loading of the structure is greater than what structure can support, and it is collapsing in the wall, and creating a compression tape crack, which would be indicated by a perfectly level foundation, or more stress fractures on the slab, pushing down, if the slab is going down as well. In any case, the compression tape cracks indicate some very specific failures, and usually are not related to differential settlement. Some exceptions, of course, could always apply.
The biggest problem is soil engineers gets too expensive these days at least in my area (SF)
That is definitely the conundrum. On one hand, it’s something that cannot positively be done with absolute certainty without an engineers input. On the flipside, you can spend $80,000 doing soils testing on a single property, and still not know exactly what the soils are, and how to mitigate them. Civil engineering is the most inexact form of engineering that exists. For that reason, there will always be an associated risk. So you have to find the balance between the testing of the soil and value engineering.
That being said, everything in San Francisco is expensive 😂😂😂
There are some good foundation repair experts in the area. Many of them use combinations of systems, or they specialize in a single system, such as piering, concrete replacement, drainage mitigation, or polymer injection. Notable companies in the bay area are URETEK, FRC, bay area underpinning, Ramjack, and EagleLIFT.
When these companies provide recommendations, it should be backed by an engineers analysis. Some companies opt to use engineers to create plans and reports based off of their findings, without doing an on-site investigation. This can work, but it’s sometimes very difficult and it’s a good standard of practice to have the engineer actually be on site and evaluating the issues.
From that point forward, depending on the repair type, either repair specific or site specific soils testing and analysis should be a bare minimum. In example, I could do a soils test to evaluate how deep a push pier would go, but that would only be part of the information needed for a helical pier. That would also provide good information on how deep polymer injection would need to be provided, but it would not provide soils type, which could change the type of polymer, or render the polymer ineffective, if the soil was not porous enough for the polymer to travel.
So this is probably just the long-winded way of saying there is value engineering available, but it will still be expensive, and it is always necessary.