*
Hi folks — I had a new home built this year and I moved into it in July. I recently noticed a foundation crack (poured foundation) in my basement that extends through the foundation to the outside wall surface.
My house is built on a grade that allows a “walkout” style basement in the back with a standard foundation exposed in the front. The foundation is “stepped” up on the side to transition the grade from back to front. At this step area, a window is built in and it is at the corner of the window where the crack in the foundation begins.
This makes since that a crack would perhaps form here as this represents a stress concentration zone at the corner. But when is the crack considered unacceptable? I intend on monitoring the growth of the crack but am concerned that this will need to be addressed by the contractor.
Hopefully I properly described the scenario and didn’t confuse anyone. I appreciate any responses and advice you might give.
Richard
Replies
*
My present house is of the same design as yours, with a single crack in one window corner near the step in the foundation after 23 years--only flaw. It used to weep water when the snow banks melted around it, so i had to address that with footing drains and moisture proofing (dimple plastic fabric from Dorken) from the outside. My walls had steel every four feet--hope yours does, too.
*I've been told that every house in our neighbourhood had a crack or two during the 2-year warranty period and all were addressed by the builder. As an aside, most builders have figured out that it's cheaper to fix a couple of leaks than to move up to the next plateau of poured concrete quality.
*Define "Crack"Hairline, 1/8th inch, 1/4 inch.All different. All right?James
*True -- all cracks are not created equal. This one is approximately 1/16th of an inch troughout the length.Richard
* Related reading from the Archives.Jeff
*There's information on a crack-monitoring device in the latest issue,#136, p.73. It's made by Avongard and their phone is 800-244-7241.FWIW, almost all concrete cracks. Your crack may indicate normal shrinkage, requiring only waterproofing, and not a structural problem. Andy
*A crack in your concrete wall is a sign of something gone wrong. Either poor workmanship, poor curing, poor product or poor design.Foundations are not designed or meant to crack.The foundation is the most important component of a new house and one that very little attention is given to it's performance.Concrete is not designed to crack. Concrete cracks because somebody didn't do their job.GabeGabe
*I still remember an "This Old House" episode where they've just poured a new foundation wall for a barn-to-house conversion using a wildly expensive exotic concrete mix (fiberglass shread, micro-beads, acrylic binder, and who knows what) to what looked like double thickness. The pour is being over-seen by a senior sales-type from a large ready-mix company (who probably donated the 'crete). Steve Thomas turns to Norm and says something like: "At last, crack-proof basement walls"; at which point the concrete salesman almost has a heart-attack on camera and interjects something like: "no, no; crack-resistant, less likely to crack, ... {cut off by Steve and Norm}".
*For a cheap and efficient way of monitoring the crack take a strip of window glass, about 2" x 1/2" and glue it to the concrete, spanning the crack. You must use a non-flexible glue, two part epoxy is best.With the slightest movement in the crack the glass will break, or separate from the glue.
*PRECISELY the same crack I have and posted about several months back. (And I have NO steel in my walls;only in the footings!)I've deduced that the foundation footing has to step down almost directly under where the wall steps down for the window area, leaving only about 4.5'of concrete between the footing and the corner. (MOST of it on ledge)I wasn't there, the foundation sub COULD have tossed some steel in if he wasn't drunk (I counted the bottles) or even have called and told me it didn't look right.........Bitter? Noooo....not me!Anyway, I drilled straight down into the crack from 2 spots in the corner, thinned down some anchor cement and poured it in so it flowed down the crack.Nope, didn't work. That cracked too, but at least it's a much thinner crack.I don't expect the footings to drop any further, so I drilled a 3/4" hole straight through the crack about 8" down from the corner, slid through a 3/4" threaded rod with 4X8" plates on either side and bolted it tight. Since the lower section of wall has a 12' retaining wall perpendicular to it my only concern was keeping the wall on both sides of the crack in plane. No problem with water and not much soil pressure either.It's now 2 years after placing the concrete so I think it's done and done.
*Cracks 101.A crack is a visual reminder that something is wrong with your foundation.A crack can be structural. This is caused by shifting or settling of the ground. Backfilling before the concrete has cured will cause a shift or pressure crack. Founding your footing on unstable or inconsistent soil will cause uneven settling and will also crack your foundation. Accelerated curing or excessive water in the mix will also cause shrinkage cracks that may appear to be structural in nature.Stress points are also a concern. Windows, doorways, inside corners and attached garages can all cause cracks to occur.Not having steel in the footings or tops of walls can increase the size of the crack but normally can't altogether prevent the crack from starting.Cracks are NORMALLY the product of 2 or more mistakes in pouring.Never hire a contractor who can't warrantee his work against cracks.No one should have to live with a cracked foundation.Gabe
*Gabe,I don't believe I got the full understanding of your post. Are you saying that 'any' crack in a poured wall constitues a problem? If so, what about expansion joints where you would expect a shrinkage crack to occur?Michael
*Michael,For the sake of discussion and to ensure that we're comparing apples to apples lets focus on "residential" foundations.A typical house foundation would be 1500 sq. ft. in area, 8 feet high, 8 inches thick over a 24" by 6" footing. 2 to 4 windows.What I'm saying is that for a crack to occur is this foundation, would mean that something is wrong.A foundation this small has no reason to shrink enough to crack, should easily be founded to carry the load and should resist all natural lateral forces.Millions of foundations have no cracks. We focus on the ones that do and for some unexplained reason we accept it as a fact that concrete cracks when in fact is doesn't.Gabe
*GabI agree with what you are saying -- I believe the crack is the fault of the contractor. Of course my concern now is what is acceptable -- you say that it shouldn't have happened and I agree. But that doesn't seem to be the popular wisdom. Thanks for your input.RegardsRichard
*Sorry about your name Gabe -- I am still figuring this computer thing out.Richard
*Richard,The important thing is whether the crack is increasing or not,ie, is the foundation settling. The crack should be sealed anyway to stop water penetrating and corroding the rebar but you'll have to monitor it for movement. If it is moving then the whole situation becomes a lot more serious.
*Richard,If the crack is 1/16th of an inch wide and hopefully stable, you should be able to use an epoxy or expanding cement plug to seal it.There's a hundred things that can cause a crack in concrete and sometimes finding the cause can be like finding the source of a leak in a flat roof. Even with computerized batching, the human element is still the biggest variable. Once caught a driver stopping for lunch with a full load on.You can easily monitor the progress of the crack by inserting a nail snuggly into the crack, a month later check to see if it's still snug and every month later.Gabe
*just dig out the outside of the crack fill it with hydraulic cement and tar it over.
*Gabe, you described a 24 in. x 6 in. footing in your post, above. Is that standard in your neck of the woods? I've only built in NJ and CT, but all of those footings were either 10 in. or 12 in. thick, for two-story houses. BTW, no steel in the walls is typical of tract-house foundations in the regions where I've built.Andy
*Andy,It was only an example given.There isn't a set size for footings. They are dependant on soil conditions and loading requirements. What is a fact is that foundations need not crack.Gabe
*Thanks Gabe. I was only curious if that was a standard size. Differences such as that catch my eye, because I end up wondering which is over-building and which is under-building.I do agree that foundations need not crack. My intitial comment should have been that many do, but it's often not a serious structural defect. Avoidable? Probably. Will the house fall down? Likely not. Even having been a spec builder, and so understanding that every extra dollar such a builder spends comes directly out of his own profit, I'm astounded that people omit rebar. When I built my own foundation, I placed #4, grade 60 rebar every 16-in. horizontally, every 2 ft. vertically and diagonally at every window and door corner. By code, none was required, but this $300 worth of rebar bought me both peace of mind and a crack-free foundation (I'm pretty sure of that - hard to say with ICFs).
*Someone told me the other day that our new code due out in January b (Canada alert ! Canada alert ! Xenophobes take caution)will have new standards for non-metallic rebar for spans etc. (mostly applies to bridging and commercial structures). They've even been running pilot down Adrian's way on a warf with electronic sensors imbedded in the non-metallic rebar that's hooked up to the internet and stresses, deterioration, or movements can be remotely measured.
*I don't know about anyone else, but my wall crews and flatwork guys give me a guarantee. Concrete is guarateed to do 2 things, get hard and crack. Every foundation I do gets a keyway in the footing and rebar to tie the wall. Every 8' wall I pour gets three horizontal runs of rebar and I still get cracks at places like wall jumps (ie.) step downs, at beam pockets and at some window openings. Every basement floor I pour gets fiberglass reinforced concrete and cuts at the jogs and bump outs and i still get cracks. What I rarely get is a faulty or problematic foundation (ie.) leaks. I never get a stress related foundation problem. On the very rare occasion I have one that gets a minor leak it is usually at a pan seam. Easily repaired by epoxy injection or at worse case exterior filled with hydraulic cement and re-tarred. I can't imagine ther is an area with worse weather changes or conditions as central Iowa, I seem to fair just fine.
*HomeBldr,I can assure you all of your cracks are stress related and all could be avoided.If most of your foundations or slabs have cracks, then you or your crews are doing something wrong. Your missing on some detail.Are you using expansion material around your slab?Are you compacting the sand base properly and evenly?Are you isolating all wall,posts and columns from your slab?Are you pouring concrete or soup?Are you satisfied to patch a crack instead of preventing them?Gabe
*
Hi folks -- I had a new home built this year and I moved into it in July. I recently noticed a foundation crack (poured foundation) in my basement that extends through the foundation to the outside wall surface.
My house is built on a grade that allows a "walkout" style basement in the back with a standard foundation exposed in the front. The foundation is "stepped" up on the side to transition the grade from back to front. At this step area, a window is built in and it is at the corner of the window where the crack in the foundation begins.
This makes since that a crack would perhaps form here as this represents a stress concentration zone at the corner. But when is the crack considered unacceptable? I intend on monitoring the growth of the crack but am concerned that this will need to be addressed by the contractor.
Hopefully I properly described the scenario and didn't confuse anyone. I appreciate any responses and advice you might give.
Richard