Basement wall horizontal crack, Carbon fiber straps?

[Windgate]

I have a horizontal crack in one of my basement walls. The crack is about 2/3 up from the slab in a mortar joint. The wall is CMU block. The crack is about 30 ft long. The inward deflection is minor (maybe ½ inch over the 8ft high wall) but it is obviously something that I would want to address before finishing the basement (a few years from now). Right now I am working on improving the drainage around the foundation (new larger gutters, trench downspouts away from foundation, etc.).

We purchased the home four years ago. At the time the home inspector did not think that the crack was substantial and it has not increased since then. I probably should have had it investigated further.

I had a basement waterproofing contractor come by a few months ago and take a look at the crack. He recommended carbon fiber straps across the entire wall (4ft on center). He came across as more of a salesman than a subject matter expert. Also, the research that I have been able to get online makes the technology seem like a gimmick.

Anyone had any experience with carbon fiber straps?

 

[matt267 PE]

While I don't have a direct answer to your questions, you might find this site interesting/informative: http://inspectapedia.com/structure/FoundationCracks.htm

 

[Dexman PE PMP]

We used carbon fiber straps on my last project. We had cast-in-place concrete stairs where the contractor f-ed up the rebar (he put only about 1/2 of what was called out due to a mix-up with the shop drawings). I don't really have the details on what specifically was used or the calculations behind them, but they've been in place for 9 months with no issues...

 

[Ble_PE]

Carbon fiber reinforcement is definitely not a gimmick, but you would need to hire a professional with experience in the design and installation of it. My graduate school advisor was big into FRP reinforcement and we actually designed and installed FRP on basement walls for a local business in my graduate level masonry class. That being said, you need to get an engineer's opinion on the cracking and if FRP is a suitable solution.

 

[Road Guy]

[SIZE=medium]I guess that might work but only if you were really worried about the wall collapsing. CMU’s are good in compression and that’s about it. Cracks in them are common but I can’t envision spending the money to put them on a residential house.[/SIZE]

[SIZE=medium]We used them on two bridges back in Georgia as a pilot project. Cost around $100K per bridge to extend its life 10 years.. I voted to put the $100K we spent in the bank towards the future $600K to replace the two lane bridge (I lost) ....better salesman than me...[/SIZE]

[SIZE=medium]But watching these straps go in was a pretty big ordeal, lots of prep work, the guys knew what they were doing, I would be worried of trusting a residential contractor to do something like (just my opinion)[/SIZE]

 

[MA_PE]

The mechanism sounds odd. Even if the 8 ft wall wall completely below grade that means your crack is about 3 ft below grade. The lateral soil pressure is pretty low there. CFRP strips would help bending strength but you really don't have a lot of development length above the crack. You should dig out the soil to the depth of the crack to see if the mortar is deteriorated, missing or crushed on the outside.

You don't say how old the house is.

Do you have leakage or staining at the crack. How long is the wall and is the crack centered in it? Is the inweard deflection greatest at the center?

You'd need to have a reputable designer/installer for the CFRP repair, otherwise you just get some fiber strips stuck on the wall but they may not be able to take any load.