New Home Build – Concrete Wall Crack
Hillman80
| Posted in Construction Techniques on
All,
I’m building home and we had our basement wall poured on 10/23, excavator backfilled in preparation of pouring basement floor and I noticed this crack in what will be a retaining wall. Today marks the 47th day, I can’t imagine this is typical and I’ve already sent pictures to my builder. What is a typical crack if there is such a thing? Wall was poured on a footing and ground was virgin clay. Any ideas of what could have caused this? Excavator may have lumped it but I haven’t inspected that closely yet.
I’ll attach pictures tomorrow, iPhone pix are too large to attach
Replies
inside corner view
outside corner view
footing view
What, if anything, is attached to those loops along the wall?
What kind of material was used to backfill?
and, of course, who did the engineering?
form view
full view
Was the wall reinforced? Judging from the footing size, it wasn't engineered as a retaining wall
How soon was the wall backfilled? Concrete takes 28 days to cure.
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“[Deleted]”
You are going to want your engineer to take alook at the crack. Shrinkage cracking of concrete is typical but the location of that crack has me concerned as it's right where the wall changes direction. I wouldnt leave it up to the builder he has a vested interest to not make a full repair. An engineer's report should address your concerns
Thanks Sawdust Steve
wzlsg & Sawdust Steve,
Here are the footing details from my plans. It looks like our Architect/Designer noted to have this covered by others, so I'm guessing this is their way of covering their A$$, and it probably places the responsibility on my Builder to consult an engineer specializing in retaining walls to determine exact footing needs in a engineers report. I highlighted the areas I think both of you are probably referring to, 50" X 13". Do I understand this correctly?
I'm building for the first time and I'm trying to be proactive on as much as possible but don't know what I don't know.
Thanks in advance
Snip from our House Plans showing foot detail/notes.
That's what the industry calls deligated design. The architect has delegetated the design to others. In otherwords your builder had the responsibility to subcontract the design work to an engineer.
You should hire an engineer to review the adequacy of what was installed and what needs to be done to rectify,,,
Having had a few retaining walls engineered (and then I installed for myself), I can assure you there is no way that is going to pass muster for a retaining wall. I had a 3' wall out of the ground, retaining a slope uphill behind it, and I needed a 6' wide footing, and the soil coefficient of friction required a whole lot of weight (24" thick footing). Your foundation guy throwing this footing and wall in doesn't count for what the architect noted there.
You have a couple of things going on here. First off, you mention at least some of the walls being backfilled before pouring the basement slab.. Basement walls are a bit different than cantilevered retaining walls. They need to be tied to the floor system above in order to resist the soil pressure. They can have a much smaller footing, but the floor system needs to be in place and correctly connected to the wall before significant backfill on the "outside" of the wall. The cantilevered retaining wall is a different beast. Since there is no floor above to "lean on" the wall has to cantilever from a much larger footing.
In both cases there are some cookie-cutter designs in IRC that spell out footing size, wall size and reinforcement, etc. for a specified wall height and backfill height, but a contractor would need to hire an engineer if the design is outside of those tabulated heights. Either way in your case I would hire an engineer to look things over and help you decide what needs to be done moving forward. Based on the photos it looks like you have a few different conditions, potentially some "cowboying" on the part of your concrete guy or contractor, and and several things going on. I would recommend getting some oversight. Basement walls are a pain if you have issues to deal with for years to come...
That is a tiny footing for a retaining wall. I would expect them to be 60 inches wide or more for that wall height. For the house I currently have under construction the retaining wall footings are 14" thick and 7' wide at wall heights of 8-10'.
Are the rings for some kind of geotextile holdback system? If so has it been installed? That may explain the small footing, but improperly installed geogrid would definitely explain the cracking. Could you link the footing engineering page from your house plans?
To help with some practical advice, it would be good to know where this foundation is location. Climate has an influence on how retaining walls should be designed. Also, when the final finish grading is complete, what is the height difference between the high side grade and the low side grade?
[Structural engineer in CT]
Regarding:
- What, if anything, is attached to those loops along the wall?
- Are the rings for some kind of geotextile holdback system?
Those are the ends of the ties used with the formwork system. The forms on each side of the wall must be tied to each other to maintain a uniform wall thickness.
[Structural engineer in CT]
What is the current state of affairs with your builder & foundation contractor?
If you've reached a resolution, then there's no sense in getting into the "would have, could have, should have" discussion via this forum.
If a resolution is still being debated, then I'll provide a more detailed response with suggestions.
[Structural engineer in CT]
Any crack in the wall indicates that the construction process was carried out incorrectly. The problem could arise when you mix or install a wall. It's hard to conclude from the photo; it's better to contact a specialist who can inspect the wall.
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There are two types of concrete:
1. Concrete that has cracked.
2. Concrete that hasn't cracked yet.