Unusual residential structure response 4

[EDB9]

Hello,

I am working with a warranty department for a major home builder. A residence that took occupancy last year is a large three story residence with a slab on grade and turndowns around the perimeter. The lot was a cut lot and the slab bears fully on residual soil. We had no involvement with the initial site testing and I have a one pager that says it’s good. Well I’m questioning that entirely because the house has thousands of nail pops, drywall separations, molding separations, and they increase in numbers daily. A brand new house should not do this! Across the street is another development being cleared and grubbed immediately adjacent, and goes for probably about a mile. I had HABs conducted and found extremely soft blow counts, from 1 to 4 on the front left side but as you went to the rear left side, the counts were mostly acceptable >8. Lab testing indicated mostly ML, MH, and SM. All samples were damp or wet with no groundwater table found at 10’. Organics are present in some samples that haven’t been tested yet. It has been a rather wetter season lately so I suspect that’s why the moisture is retaining. I am at a loss of what could truly be causing this. There was information on the subdivision geotech report stating two lots over was a large organics pit that required soil remediation, but that was a fill lot anyways. I did a quick perimeter check to see if I could see any drainage issues or cracks in the slab but it was pouring rain so it was a rushed effort and I was sans umbrella. I couldn’t see the interior slab because of the floor coverings but I would have expected to see something somewhere in the floor tiles if there was differential settlement occurring. Only in the vertically mounted tiles did I see any separation.

Here is a sample picture of the stairs to the next floor up. The blue painters tape are where the homeowner has marked all the spots that have pops, pulls, separations, etc. The landing in the photo is one of two bouncy areas with excessive deflection.

The warranty department made repairs once already this past winter and within a week they all started coming back! So they stopped all repairs until we can fix the source of the issue causing the distress.

Here’s the big question. How do I fix this? I really don’t want to have to bring a drill out and do SPTs but if that’s the only option, then that’s gonna have to be what happens.

Has anyone ever experienced issues like this? If so, what was the issue and fix?

 

[phamENG]

I dealt with a similar situation - three story house on a slab on grade with cracks, nail pops, and uneven floor. Difference was that it seems to have taken a long time to get that way (house was over 20 years old by the time I got the call).

I determined that the issue was in the sand fill below the slab (in my area, every properly built SOG has a compacted base layer of porous material - either sand or gravel). I suspected that they never compacted it - just dumped the sand in and poured the slab. The movement in the slab was consistent with the amount of consolidation they should have achieved by compacting the soil.

Then I got called back because the problem didn't go away completely. The slab wasn't moving, but wall cracks were still occurring on the second floor and third floor. Problem turned out to be that a bearing wall on the second floor was offset from the wall below by a foot with no transfer mechanism. Based on the picture, it looks like your issues are on the first floor, so framing is unlikely to be the culprit. You probably need to get a boring right next to the house and see what you have going on right there.

 

[oldestguy]

I suspect the lumber was very high in moisture and drying took place. As the wood shrunk the nails had more room. I'd check with wood experts, such as the US Forest products lab in Madison, WI. Maybe a publication from them on this and you maybe can speak with an expert, free. As to the dry wall, that also may have some volume change along the way.

 

[EDB9]

phamENG, that is just one area of the house that I had a pic on my phone for. It’s not just one area, it’s in every single room in the entire house. There isn’t a single wall or ceiling anywhere that doesn’t have this occurring so it’s not localized to any one area.

I took 6 HABs and ran lab testing, atterburgs and grain size. I’m also going to do a couple hydrometers because it’s holding a LOT of moisture.

 

[EDB9]

oldestguy,

That could explain why it initially happened but what about now? They repaired all of it extensively and it didn’t even take a week before they all started showing back up. That almost makes me want to have them remove a few sheets of drywall so I can see the actual structure to see if the studs have shrunk. I just find it a little perplexing that it is so widespread.

There was another house being constructed immediately next door at the exact same time and it does not have any of these issues so that’s the only reason I didn’t go directly to a timber moisture issue and immediately thought if settlement or even liquefaction possibly due to the soil types.

 

[Phil1934]

I would not think settlement as no seam splits.

 

[EDB9]

Phil1934, they aren’t seen in the photo posted but there are a lot throughout. Ceramic tiles are separating and so is the floor and ceiling molding. The drywall had seams that were mudded over and they were in almost every room.

 

[oldestguy]

Does not seem related to support. If lumber was handled the Very SAME, maybe rule that out. Then I'd question the dry wall material. Is it from a different source than neighbor? If there is such a thing as a dry wall expert, I'd go there.

 

[EDB9]

oldestguy,

Both houses were under construction at the same time. I don’t have any info on the material supplier but I would suspect the home builder would have had it delivered from the same source since the houses were pretty much on the same erection schedule.

Unfortunately, I know of no drywall experts. Only how to hang it as an amateur! Ha!

 

[r13]

Did you check plumb and levelness?

 

[EDB9]

retired13, that I have not. We do have a floor flatness machine in house and I could take a level to some of the walls to confirm they’re plumb. But I didn’t see anything that looked like it was skewed. There were a few bouncy floors but when I looked at the joist layout plan, they used code min for deflection and maxed out the spans which explained the bounce in the master bedroom but that was really the only location that had floor flatness issues that I could visual determine.

 

[oldestguy]

Do a Google search for "drywall shrinkage"., etc. When I just did it they talk of this problem and blame a lot on how the drywall was "hung". Apparently it takes an experienced worker.

I'll add, this old guy has seen hundreds of house drywall problems as related to settlement. None of them appeared like this job. I'd rule out settlement.

 

[SlideRuleEra]

...found extremely soft blow counts, from 1 to 4 on the front left side but as you went to the rear left side, the counts were mostly acceptable >8.
All samples were damp or wet with no groundwater table found at 10’.
It has been a rather wetter season lately so I suspect that’s why the moisture is retaining.
There was information on the subdivision geotech report stating two lots over was a large organics pit that required soil remediation,
I am at a loss of what could truly be causing this.

I really don’t want to have to bring a drill out and do SPTs but if that’s the only option, then that’s gonna have to be what happens.

Why the hesitation?

Soil can be VERY local (e.g. the organics pit near your project). Borings determined that a client's house had been build directly over a narrow former tidal creek bed that had been filled with garbage over a 200 year time span. The entire house didn't settle, it "bucked" (up and down) as soil moisture changed, wreaking havoc with the walls, ceilings, floors, windows, doors, brick veneer and chimney, plumbing (sewer pipes pulled apart inside the walls, etc.). None of the surrounding houses had problems.

http://www.SlideRuleEra.net

 

[r13]

I would agree with OG on this one. Differential settlement will usually cause large cracks, which most likely to appear on the walls. But nail popped out? Sounds like the result of shrinkage and expansion, I bet the wall has bowled, and I would monitor the change on indoor humidity closely. Where the house is located?

 

[EDB9]

One of my field techs took this picture. The crack runs the entire side wall from front to back.

 

[EDB9]

The residence is in Charlotte, NC.

 

[miningman]

Well ya better hope the builder never sees that photograph!!!!!!!!!!. The plastic trough at the end of the downspout is funnelling water back towards the foundation. That might not be the primary deficiency but it would be more than adequate for a competant lawyer , or engineer , to sow doubt.

 

[miningman]

Not to mention the fact that the high ground at the back of the house clearly funnels all drainage back towards the foundation..........its no wonder the whole house is settling!!!!!!h

 

[r13]

As perimeter footing settles, bulging of interior floor is possible, that might introduce compression into interior walls...Do need to check the levelness/plumb thoroughly.

 

[oldestguy]

Let's say the wall studs were bone dry when built. The lower course of brick likely sits on the foundation ledge for it. Base plate for interior wall studs system likely bolted to foundation. If the studs swell the base plate likely will stay put. Swelling wall studs will push out the brick that is attached to them. Look at interior at the wall at floor, behind the trim. It also may be pushed inward.

This may or may not be true depending on what the screws do. Assume they did use screws. Are the heads sunk in or pushed out. Above would apply to screws sunk in. Nails might do the same.

Any outside water at base of wall is very unlikely to get up to the second floor, etc.