Bowing basement wall 1

[anthon89]

Hi everyone,

I have a basement wall that is bowing, and I’m exploring different methods to reinforce it. I've attached pictures of the wall in question for reference.
The wall is about 10m wide and 2m tall.

Current Considerations:​

I’m leaning towards using carbon fiber strips as they seem to be the most cost-effective option. Here's a video summarizing various reinforcement methods, including carbon fiber strips:
YouTube Video: Basement Wall Reinforcement

Alternative Idea:​

Would it be feasible to cast a new concrete wall, approximately 100-150 mm thick, with centrally placed rebar? My thought is to connect this new wall to the existing foundation and floor joists, potentially using shear studs to tie it into the existing wall.

Since the basement is only used for storage, losing a small amount of space is not an issue.

Wall Realignment Option:​

If I want to straighten the wall before reinforcement, I assume I would need a ground anchor system.
However, this seems like a costly alternative.

I’d appreciate any advice or insights regarding:

1. The effectiveness of carbon fiber strips for my situation.
2. The feasibility and structural integrity of adding a 100 mm thick concrete wall as reinforcement.
3. Whether straightening the wall first is necessary, and if so, recommendations for cost-effective solutions.

Thanks in advance for your input!

 

[SWComposites]

figure out the cause of the bowing/cracking first.
are there drainage issues outside?

 

[anthon89]

They redid the drainage about 10 years ago. The owners have lived in the house for 2 years and the cracks appear the same. I suppose the cracks come from settlement in combination with hydrostatic pressure. Hard to say. The soil is clay/silt

 

[anthon89]

No drainage issues

 

[pds1963]

To me this looks like there is a high content of moisture In the soil and frost has heaved the cmu causing the joints to shatter and push the blocks in, must likely not reinforced vertically or horizontally. Cores not filled correctly. Can be repaired by supporting the structure above, which would require a footing below, using 2x6 doubled and plated above to raise about 1/4" and excavation of the soil demolish existing causing and replace it filling cells as you go, with durawall every 3rd coarse and 5/8 bar every 3ft. Use double bars horizontally in a bond beam and fill and set anchors as to specs for the area

 

[pds1963]

To me this looks like there is a high content of moisture In the soil and frost has heaved the cmu causing the joints to shatter and push the blocks in, must likely not reinforced vertically or horizontally. Cores not filled correctly. Can be repaired by supporting the structure above, which would require a footing below, using 2x6 doubled and plated above to raise about 1/4" and excavation of the soil demolish existing causing and replace it filling cells as you go, with durawall every 3rd coarse and 5/8 bar every 3ft. Use double bars horizontally in a bond beam and fill and set anchors as to specs for the area

I have also seen this issue caused by landscapers when a bed is along the building not pitched properly causing it to retain moisture from mulch or other especially if roof drains are present.

 

[ANE91]

Carbon fiber is the #1 repair method in my market for this condition. They are anchored at the top to the double top plate and at the bottom to the footing. Some edge-of-slab demo is required. Contractor can tension the strips to the straighten the wall and close the cracks. We’ve been doing it for years. Feels like every other basement develops this issue at some point.

 

[XR250]

Carbon fiber is the #1 repair method in my market for this condition. They are anchored at the top to the double top plate and at the bottom to the footing. Some edge-of-slab demo is required. Contractor can tension the strips to the straighten the wall and close the cracks. We’ve been doing it for years. Feels like every other basement develops this issue at some point.

In my market, the carbon fiber strips are just epoxied to the masonry or concrete wall. There is no attempt to straighten the wall. I don't see how that is possible anyhow without excavating it. Also, how on earth can you get a good enough connection to a double top plate for these to work?

 

[ANE91]

In my market, the carbon fiber strips are just epoxied to the masonry or concrete wall. There is no attempt to straighten the wall. I don't see how that is possible anyhow without excavating it. Also, how on earth can you get a good enough connection to a double top plate for these to work?

Yes, excavation is required to re-plumb the wall with jacks, then the carbon fiber is installed, and then the soil is backfilled, which tensions the strips. Replumbing is not always necessary.

Attached photo from recent inspection illustrates the top anchor into the sill plate.

 

[XR250]

Are the strips epoxied to the wall? If so, at what stage? If they are epoxied prior to the backfill, then the top and bottom connections are not seeing any load. I can't imagine the top connection doing a whole lot anyway.

 

[jerseyshore]

Are the strips epoxied to the wall? If so, at what stage? If they are epoxied prior to the backfill, then the top and bottom connections are not seeing any load. I can't imagine the top connection doing a whole lot anyway.

Some brands like The Reinforcer do not get attached to the top plate. A brand like Rhino uses a little bracket that gets screwed into the double plate.

But you are correct, the connection to the sill plates doesn't really do anything besides help them align the strap when placing it on the wall and keeping it tight/ straight. Same as if rebar was placed, it obviously does not get connected to the sill plates.

During a basement repair job if I think the sill anchor bolts are bad/ missing I specify the Simpson retrofit connectors.

I am also like you where I've never heard (or seen) anyone try to straighten an old cinder block wall. That seems crazy to me.

 

[XR250]

I'm working on one currently where the basement walls are bowing and the previous homeowner decided to just build new 8" CMU walls inside the existing. No connection to the existing walls or floor system WTF? The new owner is a little pissed to say the least - especially when I pointed out that his floor diaphragm is also being slid backwards by the force of the 9 ft. of backfill (1940's house w/o anchor bolts).

I think I am going to have him remove the new CMU walls and add soldier beams and tie-backs (at least at the front wall to mitigate the backfill pressure pushing the house backwards)

 

[jerseyshore]

I'm working on one currently where the basement walls are bowing and the previous homeowner decided to just build new 8" CMU walls inside the existing. No connection to the existing walls or floor system WTF? The new owner is a little pissed to say the least - especially when I pointed out that his floor diaphragm is also being slid backwards by the force of the 9 ft. of backfill (1940's house w/o anchor bolts).

I think I am going to have him remove the new CMU walls and add soldier beams and tie-backs (at least at the front wall to mitigate the backfill pressure pushing the house backwards)

Feels like at this point they should just get a brand new wall in the correct place. Is access on the outside too difficult to excavate?

We use walers/ soldier beams a lot when removing/ replacing the wall is too difficult. What kind of tie-backs do you use?

 

[XR250]

Feels like at this point they should just get a brand new wall in the correct place. Is access on the outside too difficult to excavate?

We use walers/ soldier beams a lot when removing/ replacing the wall is too difficult. What kind of tie-backs do you use?

Unfortunately, they got some bad advice (IMHO) from another engineer who told them to excavate the entire foundation, re-waterproof/drain and backfill with gravel. so they already did that. One of the inner CMU walls actually developed a crack during the backfill operation.
I typically will install soldier beams with an MC6x15 wailer and helical tie-backs.

 

[jerseyshore]

Unfortunately, they got some bad advice (IMHO) from another engineer who told them to excavate the entire foundation, re-waterproof/drain and backfill with gravel. so they already did that. One of the inner CMU walls actually developed a crack during the backfill operation.
I typically will install soldier beams with an MC6x15 wailer and helical tie-backs.

Who tells someone with a bad wall to excavate and not even replace the wall. That's the hardest part of the whole thing. Wild.

I've never used helical tie backs on basement walls for permanent support, just for shoring uses. If a wall is that bad it gets a new wall or a full steel waler/ grid support.

Many "foundation repair" contractors want to use those to correct the wall. Do you have a lot of success just using them to brace an already-bowed wall?

 

[JoshPlumSE]

Would it be feasible to cast a new concrete wall, approximately 100-150 mm thick, with centrally placed rebar? My thought is to connect this new wall to the existing foundation and floor joists, potentially using shear studs to tie it into the existing wall.

I would think this would be feasible.... with shear studs / dowels into the existing wall for connectivity. The biggest problem with this is how you're going to do the foundation for the new wall.....

FWIW, I've learned a lot from this thread already. I didn't realize that the Carbon Fiber repair method was so widely used now. That's really good to know. Thanks everyone!

 

[XR250]

Many "foundation repair" contractors want to use those to correct the wall. Do you have a lot of success just using them to brace an already-bowed wall?

I spec them regularly with good success. But only when carbon fiber or soldier beams alone are not a good solution.

Who tells someone with a bad wall to excavate and not even replace the wall. That's the hardest part of the whole thing. Wild.

Right? To be fair, who knows how the conversation actually went. Maybe the homeowner cheaped out.

 

[jerseyshore]

FWIW, I've learned a lot from this thread already. I didn't realize that the Carbon Fiber repair method was so widely used now. That's really good to know. Thanks everyone!

Carbon fiber is basically the only repair method that is used now around NJ. I haven't seen anyone add rebar & grout in like 5 years. 10 years ago CF straps were the innovative thing that only a few guys knew how to do. Now every bozo sells CF strap repairs like they are fruit roll ups.

Maybe the homeowner cheaped out.

I think I'm going to get this on a t-shirt.

 

[SWComposites]

Now every bozo sells CF strap repairs like they are fruit roll ups.

oh my, as a long time composites expert (aerospace) this scares the **** out of me. there are a LOT of things that can go wrong with composites design and install.

 

[XR250]

I have seen them installed without even removing the paint from the CMU wall. They were peeling off like sunburned skin.