Basement floor sinking?

[usmaak]

I've been puzzling this out for a week. I'm not sure how long this has been going on. The enclosed pictures are the basement steps in my soon to be eight year old home. The basement is unfinished and the steps go down to a landing and then down the rest of the way to the basement. The only wall is the one in the pictures and there is framing that goes under the landing for storage. The steps appear to be sinking and have separated from the edge of the wall. Because this is Colorado, the wall is a floating wall and the steps are attached to the landing and not to the floor. I talked to a structural engineer and he said that he can't really tell what's going on from the few pictures that I sent him, but the basement slab might be settling. I also attached an image of the floating wall. Some of the spike still have some room to move and some are right at the very top and have no more room.

I have literally no idea what I'm doing, but I did some very unscientific measurements tonight. I used a laser measuring tool to go around the basement and measure the distance from the floor to the first floor subfloor I found that the floor on the south side of the basement was almost an inch lower than the floor on the north side of the basement. The lowest point was the SE corner of the house but the SW corner was also lower. It sloped up pretty quickly as I moved to the north.

The basement floor is a bunch of big concrete blocks with control joints. There are a few small cracks along the control joints, but no cracks on the blocks themselves. I can't check the basement walls for cracks because the builder put up insulation on all of the walls. I looked on the outside and aside from a few very small hairline cracks on the concrete above one of the basement windows, I can't find any. The walls inside show no cracks and I have only one door that gets sticky in the winter. It's the bathroom door and I think that has more to do with the way that it was framed. It also has a vertical crack above it. It is not on a load bearing wall.

I am just trying to figure out if I have anything to be concerned about. I know that Colorado is famous for its expansive and semi-expansive soils. I am likely going to have the structural engineer out to do a proper inspection of the property and land. I have a builder warranty on structural issues and I have two years remaining on it.

And information or advice would be appreciated. I know nothing about this type of things, so I'm sorry if my explanation about what's happening is difficult to understand.

Thanks

 

[Steve123]

Construction that I am familiar with has the basement slab sitting on top of the footings, so I don't understand how the slab can sink. But you might do thinks different in Colorado. I have never heard of a floating wall.

 

[bud16415]

This method of construction is also strange for where I live.



It looks as if the walls were framed hanging with a slip feature at the floor anticipating movement. The only time I have seen it here is with interior walls in log homes where they know the logs will settle over time so they do the reverse and make the ceiling joint able to slip and then have a molding the wall can move behind.



I think where you live and you talked about it some there are special soil conditions most of us here haven’t encountered before.



What you have may well be normal and expected I just don’t know. Local sources like the person you are in contact with likely will be able to tell you.

Keep us informed.

 

[Guzzle]

Research MudJacking, it may buy time.

Are corporations working in your area below the ground, injecting fluids, extracting minerals?

Underground acquifers wearing away subsurface limestone? The US Geological Survey owes you straight answers in this regard.

 

[usmaak]

Research MudJacking, it may buy time.

Are corporations working in your area below the ground, injecting fluids, extracting minerals?

Underground acquifers wearing away subsurface limestone? The US Geological Survey owes you straight answers in this regard.

Not to my knowledge. Most of the oil/gas extraction is taking place 20+ miles to the NE and while they do use horizontal fracking in this area, I don't think that they're going under this town. I have asked my neighbors if they have noticed any issues and I'm the only one that has any problems. Of course. I've always suspected that there might be something going on. There were so many issues with this house after I moved in. The builders fixed a few of them on warranty and then abdicated on the rest after they picked up and moved out of state. I ended up tracking them down and we settled on an amount that was probably badly unfair to me, but it wasn't worth pursuing legal options so I just took what I could get. I've regretted my decision to move here every day since.

 

[Guzzle]

Measure the same gap once/month to see whether it's stopping or slowing. The gap may vary by season.

Your mortgage company will get nervous if they find out about this.

 

[usmaak]

Measure the same gap once/month to see whether it's stopping or slowing. The gap may vary by season.

Your mortgage company will get nervous if they find out about this.

Why would they care? I've never even been late on a payment.

 

[bud16415]

What is very odd and without a question your basement floor is slowly descending, is why are the footings not doing the same thing only more so as they have the full weight of the house on them. The fact that the floor is moving tells you it was designed to float and it has no weight bearing.



Then there is the odd way the stairs and stairway was framed leaving the stringers against the floor but the stairway walls hanging from the joists. So this leads you to think they knew something was going to happen.



Do you have plans to finish the basement?



I don’t think it is a real serious problem in an unfinished basement and as mentioned I would try and figure out if it has moved and stopped or is still moving.

To fix the gaps in the stair trim my guess would be you could jack the stringers up and shim under them caulk the seams. Right now I wonder if your treads are pitched forward a little.

 

[Guzzle]

Why would they care? I've never even been late on a payment.

Your house is the collateral for the loan.

Our company is asking snoopy questions & wanted me to go online & fill out a form, What are our shingles made of?, etc.
I'm not going to climb all over this house & guess at the molecular structure of its various components.
I wrote on the their letter, "The house is as it was" & did not sign my name or date it. That fended them off for now.

Our lawyer seemed to admit that when we pay off the loan balance they can extort a few extra thousand from us or else not release the lien. I expect they will do just that.

 

[usmaak]

What is very odd and without a question your basement floor is slowly descending, is why are the footings not doing the same thing only more so as they have the full weight of the house on them. The fact that the floor is moving tells you it was designed to float and it has no weight bearing.



Then there is the odd way the stairs and stairway was framed leaving the stringers against the floor but the stairway walls hanging from the joists. So this leads you to think they knew something was going to happen.

This is exactly how houses in Colorado are designed. The soils are expansive and they have to account for it in all of their construction. I am not 100% sure on how basements are built, but I believe that the floor floats. It is divided into big blocks with control joints that allow the individual blocks to move.

We have a lot of structural issues here.

My question is about what's normal. I am wondering if maybe it's settled as much as it's going to. I may also be able to file a claim with the home warranty company to get them to repair the gap in the walls. I really need to know if it is going to continue to sink and if I'm going to end up with big problems in the future. I have a structural engineer coming out in a couple of weeks to look at it. In the meantime, I've been measuring the gap between the floor and the trim with a digital caliper. There is some variation between in the distance but it is negligible. I've also been measuring the distance between the joists and the floor with a digital measuring thing and the difference is too small for it to notice.

 

[bud16415]

This makes me wonder why the floor floats/sinks and the footing supporting the house weight don’t.



I think unless we have some members from your area that understand your soil conditions we might not be as much help as you will find talking with local building folks.



Around here if we get involved with building on poor soil conditions we would not work around the conditions we would try and correct the issues. Sometimes this can be quite expensive.

As far as will your insurance or such provide repairs. You will have to get in contact with them. I made my suggestion on what I would do to raise the stairs back up as a DIY solution.

 

[Guzzle]

IMO, the footings are stable because there's not much upward pressure on the footings because their "footprint" is not as large as the basement floor.

I'd ask neighbors with houses the same age about this. There may be areas nearby that have more or less a problem than yours, depending on the soil, see

"A soil textural triangle is used to determine soil textural class from the percentages of sand, silt, and clay in the soil."

"Silt is made up of very fine rock and mineral particles and has a very fine and floury feel to it. Clay- Clay is an organic soil with the highest mineral count of the other soils. ... These clay types are very unpredictable and will expand or contract when wet then often change shape when dry."

 

[Guzzle]

This has been an education. . .

"Innocuous as it sounds, Colorado’s most significant geologic hazard is expansive or swelling soil — that is, soil laced with layers of various clays. These clays cause more property damage than any other natural hazard. Bentonite and montmorillonite (weathered volcanic ash) clays—in the form of soils or soft bedrock—underlie many populated areas of Colorado. They can expand up to 20% by volume when exposed to water and exert a force of up to 30,000 pounds-per-square-foot, more than enough to break up any structure they encounter. One Denver suburb has the dubious distinction of suffering more annual monetary loss from expansive soil than any other in the nation.

Expansive soils are one of the nation’s most prevalent causes of damage to buildings and construction. Annual losses are estimated into the billions of dollars. The losses include severe structural damage, cracked driveways, sidewalks and basement floors, heaving of roads and highway structures, condemnation of buildings, and disruption of pipelines and sewer lines. The destructive forces may be upward, horizontal, or both."

 

[usmaak]

This has been an education. . .

"Innocuous as it sounds, Colorado’s most significant geologic hazard is expansive or swelling soil — that is, soil laced with layers of various clays. These clays cause more property damage than any other natural hazard. Bentonite and montmorillonite (weathered volcanic ash) clays—in the form of soils or soft bedrock—underlie many populated areas of Colorado. They can expand up to 20% by volume when exposed to water and exert a force of up to 30,000 pounds-per-square-foot, more than enough to break up any structure they encounter. One Denver suburb has the dubious distinction of suffering more annual monetary loss from expansive soil than any other in the nation.

Expansive soils are one of the nation’s most prevalent causes of damage to buildings and construction. Annual losses are estimated into the billions of dollars. The losses include severe structural damage, cracked driveways, sidewalks and basement floors, heaving of roads and highway structures, condemnation of buildings, and disruption of pipelines and sewer lines. The destructive forces may be upward, horizontal, or both."

I see cracks in the streets that are likely related to this. My driveway has always been a problem. The blocks have separated and some have sunk. The only option, other than putting in a new driveway, is to caulk the control joints to keep water out. My neighbor's driveway sunk and split in half within two months of moving in. The builder had to put a new one in on their dime. When I walk around, most driveways have issues. Concrete steps up to front doors are often crooked. I'm assuming that they do a better job of compacting the soil for a basement, than they do a driveway. And my garage has a big crack going down one block that is likely being caused by the same thing.

I wish I'd known all of this. I'd have likely either stayed put or found a different place to go. I like to joke around and say that Colorado does NOT want people living here and the only way to live here is to force it by spending money. Radon, pollution caused by geography, weeds that thrive all year round, and grass that dies if you look at it the wrong way... Water too much, you get one pest. Water too little, you get another. Reminds me that I need to get out and winter water tomorrow because it's been like two months since any appreciable precipitation and I don't want my lawn, trees and shrubs to start out the Spring season all dead.

 

[Guzzle]

The realtors must know about this. You might have a Cause of Action for fraud.

After rainfall your basement floor should rise. A sump pump may be able to keep the floor at a constant distance from your house. Or you raise the floor a half foot or so on I-beams supported by piers.

Check out "Love Canal". It seems they covered over this toxic waste dump with topsoil & built houses on top.

We bought a house near transmitting towers. I don't know if the kids who grew up here developed leukemia at above the normal rate. The station engineer told me that the field strength was reduced in our particular direction to avoid interfering with a station in Rhode Island on the same frequency.

So, in addition to asking the previous owners if there has ever been a fire or a flood or if the furnace has been unable to maintain a comfortable temperature, you should ask a whole bunch of other questions.
Then, stand by for some kicking, screaming, biting & clawing.

 

[Steve123]

If you really want to know what is going on, you need to pay the structural engineer to come over, inspect, and give you a written report. All this conjecture by non-professionals does not amount to much.

 

[usmaak]

If you really want to know what is going on, you need to pay the structural engineer to come over, inspect, and give you a written report. All this conjecture by non-professionals does not amount to much.

While it may or may not amount to much, I have literally no experience. So I am really just gathering ideas from people that likely know more about all of this than I do.

I have an appointment set up with a structural engineer after the holidays.

 

[Guzzle]

If he's from some distance from you [in suburban areas, at least 20 miles or at least 1 hour] he may be relatively honest with you & may even volunteer answers that you didn't ask for.
One answer may be, "Don't do anything."

The advice you get may well be worth the money.

Proly your neighbors have no incentive to rock the boat or go public & God help you if you do, whistleblower speaking here.

 

[BuzzLOL]

Yeah, same as Steve mentioned above, around here: the outer edge of the concrete basement floor sits on the inner edge of the concrete footer (which is 3x-4x wider than the concrete basement wall sitting on top of it)...