The foundation company just took the forms off, and when I went to take a look, I noticed three sides had this v-shaded crack on them that's visible both inside and outside the foundation wall.

Foundation 1

Foundation 2

This is for a garage, the location is New England. If water gets in those cracks and freezes, isn't that going to be a problem?

  • 2
    A photo from not-20-feet-away would be useful. Are they cracks or simply lift seams? – isherwood May 8 '18 at 14:42
  • @isherwood after doing a bit more research, it looks like these are cold pour joints: inspectapedia.com/structure/Concrete_Cold_Pour_Joints.php not sure if I should be worried about freeze cycles turning these into cracks or not. – AgmLauncher May 8 '18 at 14:52
  • 1
    They're not necessarily cold joints. A gap of only a few minutes between lifts can leave visible lines, and that wouldn't qualify as "cold". Post closer photos. – isherwood May 8 '18 at 15:13

Those cracks look like the contractors partially filled the forms with concrete and then allowed it to set up too much before coming back to fill the forms the rest of the way. It is probably not a really great problem as long as:

  1. The wall has plenty of rebar embedded in it.
  2. The outside faces of the foundation walls are treated with the appropriate type of water proofing.
  • How is “plenty of rebar” affect the placement issue? – Lee Sam May 8 '18 at 18:08

This is called “layering”and can be a problem by 1) lack of bonding, and 2) segregation of materials.

1) Bonding can be a problem, as you pointed out, allowing moisture between the pours and then freezing. This will cause leaks and possibly spalling.

In addition, and is usually a larger problem, it allows moisture to affect the rebar and cause rust. When steel rusts, it expends and can deform the wall.

2) By not compacting the two lifts together, you have “two walls”, one on top of another with a HINGE between them. Compaction prevents honeycombing and assures close contact with forms and rebar. Rebar is only effective if it is bonded to the concrete. The line is an indication of poor workmanship and thus poor bonding.

Unfortunately, it’s just unsightly now and difficult to prove inferior and needs to be replaced. Give it 20 years and it will really be an issue.

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