||10-03-2012 06:47 PM
Crumbling, 'spaling' exterior foundation walls
I've got a problem with crumbling exterior foundation walls somewhat similar to what's addressed on this post:
The wall was skim coated before this summer and signs of the spaling were covered by the skim coat. The large cracks visible in the photo are shallow and only go as deep as the skim coating that is suddenly falling off in large chunks.
The crumbling is bad enough that I can flake off the concrete with my bare fingers. I have not yet dared to dig into it to see how deep it goes. There is not a ton of evidence of significant moisture in the basement but there is one clear vertical crack and efflorescence at *other* points around the foundation. There is also an interior 'pony' wall between the full-height basement and a crawl space and that wall is spaling *very* badly.
This is on a 1924 2-story house on a raised lot with decent (but imperfect) grading in western Oregon. So there is a lot of rain and moisture but not a lot of extreme cold.
I've done a number of concrete repair projects and initially looked into doing this one myself but the more I got into it the more I felt like I was out of my league and decided to get bids from some pros. That's actually where I started to get a bit lost. I've had two contractors come out and they suggested totally different approaches. I'm hoping some of you can give me opinions about the approaches.
Number one suggested digging out the loose material, hand-washing and prepping, re-building those sections with hydraulic cement to 10" below grade, then skim coating. That's all.
The other contractor suggested doing nothing to the exterior at all but doing a bunch of work for interior reinforcement and water abatement. They suggested putting carbon fiber reinforcements similar to what's described here:
Then putting in a basement floor drainage system on the foundation footing, along the perimeter, adding a sump pump, a hefty dehumidifier, removing my old vapor barrier in my crawlspace and installing a multi-layer sealed replacement much like this one:
I can understand the need for water abatement but the wall is not flexed or bowing in any way, nor are there horizontal cracks so the carbon fiber strips are a bit of a mystery to me. Also, the basement has never had any standing water or weaping walls anything like that in the 7 years that I've lived in the house. I also don't understand how all of the water abatement and interior reinforcement is much good if the exterior wall is left as-is with crumbling material exposed to the elements.
I've also had someone else more casually mention the possibility of using Gunite or Shotcrete in the interior.