Bulging Concrete Block Basement Wall


https://www.eng-tips.com/viewthread.cfm?qid=90263 and

Please click through to the source URLs above the read the entire discussion. Copied below are only the highlights.



This seems to be a common problem in residential construction. A concrete block basement wall that is cracked horizontally (mid height) and bulging inward, obviously due to lateral earth pressure with inadequate or no wall reinforcement. What is the state-of-the art way of repairing this? I’m looking for a solution that spares the home buyer (or seller) from an extensive and costly wall reconstruction project. Any ideas or success stories would be appreciated.


I ran into a very neat detail for reinforcing masonry basement walls. The installation I saw used S3x5.7 vertical columns @ 4’ centers (you have to figure the size and spacing for your specific case) set tight to the masonry wall. The bottom of the columns had a “angle shoe” with two drill-in bolts into the concrete floor. The top of the column had an angle bracket bolted to the wood floor joist with a cap screw through the angle that could be used to adjust the force on the top of the column. Very neat detail, not too expensive and didn’t require excavation of the backfill. Also, the 3" columns would fit within a 2x4 stud wall if you wanted to firr out the wall.

I’m not sure where the detail came from so I can’t give credit for it or take credit for it.

There are a few styles of franchised remedy.

One is to use deadmen plates in the surrounding soil and plates on the interior wall. They are tied together with threaded rod. Check the Yellow Pages, most likely you can get a quote over the phone. http://www.anchoredwalls.com

Another technique uses helical piers applied horizontally.

If you get a ‘handyman’ involved, most likely the remedy will be to stabilize the wall using channel columns grouted into the floor and bolted to the floor above. If the bow isn’t more than 3 inches this remedy can be successful. http://www.durdydave.com

If you are budgeting around 10 grand for the remedy, you are in the ballpark.

How about grouting the blocks’ interior cells if they are now holllow?

I must disagree with the idea that grouting the cells of an existing CMU wall would be prohibitive.

  1. If the cells of the wall don’t align enough to allow grouting, the wall is so poorly built it should be demo’d anyway. The only difficulty I could imagine is if the block were laid on a 1/4 bond, but that basement doesn’t exist.

  2. Using a vibrator shouldn’t even be a consideration. Using a high slump mix or a plasticizer with 3/8" coarse aggregate eliminates the need for vibrating. If vibrating is something that you feel strongly about, touching it against the outside of the wall will acheive similar results.

  3. If the holes at the top course are prepared ahead of time, the pump should only have to be on site for one day.

  4. The holes in the block only need to be made with a hammer. There is no need to worry about the inside web of the block, since the sill plate bears on the outside of the block. (yes, I would perform this task from inside the basement)

  5. Trying to install a lenght of rebar would be prohibitive, but is not necessarily needed. No poured basement walls around here have re-bar mats.

I think it could be worth while to investigate the use of a fiber reinforced polymer (frp) bonded with epoxy. The frp comes in cloth like sheets and is applied similar to wall paper with epoxy. This method is used to retrofit concrete columns and bridges but I don’t think it would be too difficult to adapt for your needs. I don’t have any experience with this, it’s just an idea so I can’t say how well it will perform or even if its a good way to go. If it were my house I would at least check it out though. It would be easy to apply, you wouldn’t need to demo anything major and it wouldn’t add a significant amount of depth to the wall. Fyfe Co, LLC is a company out of California that manufactures these product and may be able to give you technical advice on the feasibility of using it in your basement.
Here’s a link to their website: https://www.aegion.com/about/our-brands/fyfe

Here are a couple sites, utilizing a carbon fiber epoxied to the cmu wall:


I’ve been involved with a few of these problems. I don’t reinforce the masonry. I use HSS sections vertically to provide support for the wall; these are at 6’ or 8’ o/c and have 3/8" thick plates on the bottom with two holes for Hilti KB3s. They are forced into place and either a ‘chunk’ of channel or dimension lumber secured to the floor joists with joist hangers and screws or lag screws for channels to brace the vertical beams at the top. The vertical HSS ‘beams’ have a couple of inches clear from the floor for deflection. The space between the HSS and the masonry is ‘dry packed’ with grout/mortar.

The exterior is excavated and patching and damp proofing / waterproofing applied if necessary.


1 Like