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Question DetailsAsked on 4/10/2013

block basement wall what is the best way to repair horizontal crack ?

The crack is app. 25 feet long. the joint is 5 feet from floor. The wall is bulging in approximately 3/4 in.

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4 Answers


This sounds like a problem that is often caused by saturated expansive soil in your yard. This crack is probably just slightly below the exterior soil grade line. It is best to have any foundation cracks inspected by a professional to ensure your foundation has not suffered substantial structural integrity problems. It is hard to give an exact solution to your particular problem without a physical inspection, however usually the problem can be resolved with improving exterior drainage and the installation of carbon fiber reinforcing strips on the inside of the bowing basement wall. Carbon fiber strips will not allow the bowing wall to be straightened but it will stabilize the wall to prevent any further bowing. With only 3/4" of bow I would not expect it to be necessary to straighten the wall. Carbon fiber installation will require a professional contractor. Be sure to have the contractor file for permits with your town!


Answered 4 years ago by Dludwig123


BE VERY CAREFUL!!! You may have a cosmetic issue that'll cost $2K - $5K to repair or a more serious issue requiring substantial labor & money to repair ($20K or up). I highly recommend you hire a Professional Engineer (PE) to look at this for you. Basement repair companies may try to "sell" you on various repairs but most are just expensive band aids covering up more serious problems; a PE is the only person who can properly evaluate the situation. It'll cost you about $250 but you'll receive a thorough & proper engineer report detailing the exact problem. It is worth the money! Please read below for our experience.

We have been house hunting for a while and came close to buying a house on the west end of Cleveland. We found a nice split level w/basement built in 1969. During the pre-purchase inspection we found a crack very similar to the one you mentioned; the inspector said this was fairly common but if I was worried I should get a second opinion (most home inspectors do not go more than skin deep and do not offer a warranty on structural soundness on the property inspected).

Since the owner/seller advertised that the basement had been recently waterproofed and had a lifetime warranty for that work, I called and had someone from that company meet me at the house to discuss repairs (I wanted to see if I couldn't get the owner/seller to pay for this...a bargaining chip). The "technician" wanted to use carbon strips to "stabilize" the crack and went into great detail about how their "patented" system worked. This is when I sensed the "hard sell" which always causes me to go into default skeptic mode; after a lot of back and forth I found the company rep I was dealing with was a salesman, NOT an engineer, NOT an installer. He wasn't a technician of any sort. Over the course of a week I ended up talking to a couple of companies and they all wanted to use the same or similar type of repair. At this point I hired a PE (cost me $250) and he concluded the house had a major structural defect and that the carbon strip method do nothing to stop the wall from eventually collapsing. He made his recommendation on what needed to be done. I talked with two construction companies and provided them with the information and they both provided rough estimates of $25,000 to repair the basement properly. Needless to say, the seller/owner disputed the findings and in the end we did not buy the house. We look at it like this...spending $250 saved us $25,000 and a lot of nightmares.

Moral of the story is this: Ensure you are dealing with a PROFESSIONAL, not a SALESMAN when having any serious work done on your home!

Source: A near miss personal experience

Answered 4 years ago by Guest_9987958


The recommendation to have a structural / foundation engineer look at it is the right answer. Interior patches, sealers, strips, etc are essentially ineffective - you need to be looking at the cause of the wall deflection. This can be due to expansive soils outside, settlement and pressuring on the wall from use of unsuitable (not free draining) backfill materials, frost pressure because of unsuitable fill materials, or water pressure from high external groundwater level that the foundation wall was not designed to handle. Any one of these can become serious, and if it has caused a significant crack and bowing so far, then will only get worse with time, possibly leading to a total wall collapse.

Engineer's inspection likely to run $250-500, and may require additonal $1000 or so in borings or local excavation to assess the nature of the problem outside. Repairs can run anywhere from $2000-5000 range for drainage control, up to $25,000 or more if you need partial wall reconstruction, which hopefully won't be the case ifg you get to the repair in time.

I would emphatically recommend AGAINST the so-called hydraulic cements or carbon fiber strapping - these do not address the source of the problem, and are equivalent to duct taping the problem - not an effective fix.

Answered 4 years ago by LCD


I am a structural engineer. What you have described is a tensile crack. This is cause due to a lack of tensile reinforcement in the masonry wall. Either the wall has no rebar inside or it does not have enough. The mortar effictively supplies no tensile strengh on the inside face of the basement wall. As the hydrostatic pressure from the soil and the pore pressure from the water behind the wall exert force behind the wall, the wall bends. This flexs the wall compressing the face of the wall against the soil and pulls the wall apart on the basement side. That is what we call the tensile force or the tension side. That is what causes the crack. In the case where your floor joists bear on the top of the basement walls that load actually helps becuase it couteracts the tension force somewhat. So, the big picture is that you need tension reinforcement. Now, since, I am not onsite and I don't intend to be I can't check the wall for possible additional problems. The base of the wall needs to be checked for possible shear problems. Shear is when the base of the wall actually breaks of an pushes into the house at the bottom. That is very rare, but does happen. Now, the fix. The carbon fiber strips are a VERY GOOD repair for this situation. I am not selling them an don't ever specify them because they are too expensive. They are not a bandaid. They are tension reinforceing and that is EXACTLY what you need. They are even better than the original rebar if it were in the wall because of what we refer to as "d" that is the distance from the centroid (the middle of the rebar) of the reinforcing to the extreme fiber of the compression flange. Since the carbon fiber is on the outside face of the masonry the "d" is larger and it gives a greater fexural capacity. The reason that I don't specify carbon fiber is that you can do the same thing with steel strips. Steel is much cheaper. I usually specify Sika SikaDur HI Mod 31 Gel as the Adhesive. But the Masonry has to be very clean to make sure that the bond is good. Also, a structural engineer needs to do the calculations to determine how much reinforcing is required for the flexural resistance. The engineering fee for this should be around $1000.00 for this inspection and design work. The construction fee should be about $3000.00 to $6000.00 depending on the contractor and their familiarity with the product.

Answered 2 years ago by PDT

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