Crack pictures

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21

Originally Posted By: David Randall
This post was automatically imported from our archived forum.


Didn’t mean to get you shook up, Tony, but it does change a few things.


First, in response to your concern with clay being suspect here; if this was caused by clay movement, there will definitely be at least one companion crack. Being in the middle of a long wall, you'd first normally be looking for two more cracks; one toward each end of that same wall. But, if this were from clay pressing on the wall, the center crack would be wide inside & tight on the exterior; from the photos yours looks to be the opposite of that. (crack looks tighter on the inside)

The other clay-caused scenario would be that part of the footing has settled, allowing part of the wall to tilt/drop. This action would be more in keeping with the V-shaped crack you have, but can only occur with at least one additional crack point.

Curing shrinkage cracks would likely be prevalent in pours done during cold weather, as many builders pour their mix far too wet and in cold weather often add hot water or calcium chloride to speed curing, however they really only accelerate the initial set, while full curing may take 30-60 days. Shrinkage cracks also do tend to appear near points where the is an expanded volume of concrete, such as this beam support column.

As to the extended measures in backing up this crack since it's on a full-depth wall, this includes the epoxy injection as mentioned before, but should be additionally reinforced with 1 to 3 vertical 4X4 I-beam columns. One column should be placed as directly over the crack as possible, preferably with an additional column no more than 5 feet to each side.

The columns have welded floor shoes with 2 holes in them; the floor is drilled at each hole and minimum ?" X 3" high-strength shoulder bolts are installed with anchoring cement or epoxy. The top of each beam is anchored into the floor framing with angle iron, blocking and/or sistered joists spanning inwards at least 6', widening the blocking in a "V" as it moves inward. (In other words you have blocking in 1 joist space at the beam, 2 joist spaces 16 to 24" away, 3 joist spaces 32 to 48" away, etc.) Angle iron is lagged, all blocking is glued and nailed. Beam height is determined by the maximum height available. (Depending on joist direction and clearance, beams may have to be cut to bottom of floor joists and anchored initially against angle iron.) The I-beam is placed as tight to the wall as possible, but walls are never totally flat and you want absolutely no voids behind the beam, so when the beam is placed it's first "buttered" with a product like full-flex mortar, then pressed to the wall and anchored.

Similar in many ways to other's methods, this is a total process developed by my Father & I which has proven 100% effective for over 20 years now.

I hope I've detailed the method in a way it's understood; let me know if I can clear any questions up. (Mark A., I've just passed along what amounts to a "trade secret" here....I hope you don't pass it on to Hague or whatever his name is, LOL)

P.S. Tony, are there any cracks appearing in the basement floor slab? If so, do any start/end near the same area of this wall fracture?

--
Do it right; Do it once

22

Originally Posted By: David Randall
This post was automatically imported from our archived forum.


More questions, Tony:


The adjacent home excavation done March 14th; roughly how close is it to yours? (specify whether talking of the actual dig or distance "house to house")

Adjacent excavation was dug on this same side as where crack appeared, yes?

Was adjacent dig also for a basement, or crawlspace/slab?

From your photos, is this crack at a stairway landing to your basement? (looks as though the floor in area towards front of home is lower by several feet from that resting on the I-beam.)

Roughly what kind of temperatures were you having when the walls were poured? (45? day, 20? night, etc.)

8" thick wall?

Full basement or basement/crawl combination? (I know you said there are no steps in the footing, but I saw what looked to possibly be a crawl vent in one of the photos.)

--
Do it right; Do it once

23

Originally Posted By: Tony Sohal
This post was automatically imported from our archived forum.


Good morning David,



I am learning so much from you. Here are all the answers:

a). The house 'dig to dig" is about 6 feet apart. And yes you can make fun of the dear/close neighbors.

b). The crack is on the same side. It is right in the middle of the wall (it is the longest wall of the house).

c). Yes, the adjacent dig was for a basement too.

d). Yes the crack is at the stairwell at the beam support.

e). No, the basement floor is not lower, it is uniform. Just the wooden stairwell is designed that way. The basement walls are 8 feet high.

e). The pour was done on December 22nd at around 35F around 3.00 P.M. and it was down to 20F at night.

f). Yes it is and 8" thick wall.

h). You are absolutely correct, as there are no other cracks, this crack is tighter inside and wider outwards.Also it comes to a stop about a foot above the footer.

i). The basement floor is not done yet.

Looking at all the above scenarios...it tends to be more towards a shrinkage crack. It did develop around 60-70 days after the pour was done. Hmmmmm. Interesting.

I am going to talk to the builder again. I will try to take some more pictures with wider angle so it gives you a better idea.

Thanks TON for all the advice. I will keep in touch.


God Bless.

24

Originally Posted By: David Randall
This post was automatically imported from our archived forum.


Good evening Tony,


No floor yet...okay...caught me off guard with that one. (In many areas the floor would also be poured before any framing began. Not that it's right, just the "norm" for this region, likely more than anything else because it would be labor-saving.)

I did have a thought as to another possible way this crack was created; this being a compression crack, and if so could explain why no other cracks have been discovered. Here's how the compression scenario would go:

The side where the neighboring basement was going in was or was almost completely re-excavated, leaving little or no backfill beside your wall. If the backfill along your front and back walls was compacted well enough, and the soil also gained some new moisture causing it to expand, this could press inward and cause the sidewall to crack outward since it had no substantial support outside to offset the pressure. To help visualize this idea, you can take a shoebox & press inward on the short ends; the long sidewall buckles outward, and more so at the top than near the bottom.

If this is what happened, the motion inward of the front & back walls would be very slight, and conceivably occur without other cracks, or cracks so minute they could easily go unseen.

While no crack is good, this scenario would be to your advantage at least from the factor that I think it would allow you to omit I-beam columns placed at the crack (which would be tough because it would cut into your stair landing space).

I'm going to put together a couple overhead outlines for you using my CAD, and will post here as photos that might be of help to you on this.

--
Do it right; Do it once

25

Originally Posted By: David Randall
This post was automatically imported from our archived forum.


Tony,


Here’s a couple of visuals based on this being a compression crack, what may have occurred & what you might find.



[ Image: http://www.nachi.org/bbsystem/usrimages/T/Tony2.jpg ]
[ Image: http://www.nachi.org/bbsystem/usrimages/T/Tony1.jpg ]

The actual complete outline of your home is likely a little different, but the primary affected areas is really where our concentration is.

--
Do it right; Do it once

26

Originally Posted By: Tony Sohal
This post was automatically imported from our archived forum.


Hi David,


God you are good. I think you hit the nail right on the head. The backfill was already in place all around the house. Then this side was excavated, it rained that night and viola, the crack appeared next day. Now they are going to backfill that excavated area. Here is the nice thing. The outline you drew about the house is exactly what it looks like. Let us see what happens. I will keep you updated.

Thanks again for all your help.

Have a great weekend my friend.

27

Originally Posted By: David Randall
This post was automatically imported from our archived forum.


Hi Tony,


Thanx for the kind words; it’s been a pleasure to try & be of help.


I did want to add that with your wall being exposed to footing depth when it rained, this crack could have one other simple cause. If the soil just beneath the footing gained a new level of moisture, the clay is also capable of heaving upward. A mere lift of 1/16" in the middle of a 40' wall 8' high would create a fissure at the top around 1/8" wide. This type of movement could also be subtle enough to not show other cracks, similar to the compression action.

I'm anxious to hear what your builder has in mind. My initial thoughts here would be that if no other cracks appear during construction, I'd be tempted to do epoxy injection now, but hold off on any I-beam reinforcement and I would not finish out any basement walls for a year or so. This allows you to monitor the walls for any further action, and place I-beams accordingly once the proper placement could be determined. Long, straight walls have long been a problem in clay soils, and in my area building codes now require any wall over 25' long to be reinforced by a "deadman" buttress on the exterior side to help counteract the inward pressure.

Not quite as good as done all at once with the wall, but still very significant, I think a buttress of this nature would be a good step for your builder to add to your wall in this area if there isn't such already. (We hadn't gotten around to that question.) If this was to be done, they'll need to do so before backfilling, and would be really simple for them if it could be formed and poured at the same time they pour the neighboring basement. (if it's not too late already)

That's all for now; keep me posted.

David

--
Do it right; Do it once

28

Originally Posted By: Tony Sohal
This post was automatically imported from our archived forum.


Good morning David,


Thanks for the reply. By the way here in Toronto, the soil we have is the sticky, Red coloured clay. So you are right, this might be the reason too.

According to the building code, we cannot finish our basement for a minimum of two years. The city actually asks people to wait for three years.

I am going to talk to the builder and will keep you posted.

Thanks again for all the help.