Foundation Reinforcement 1

[struct101]

Hi Everyone!

I was inspecting the foundation of a building and noticed a crack in the foundation (concrete) that was transferring all the way up to the 3rd floor (Bricks) of a 12 floor building. The crack is due to water infiltration from a poor and and faulty parapet on the roof. It seems like this crack is growing and I am looking at possible solutions to repair and prevent future degradation... I came up with the following:
1- Repair the bricks with brick pointing and replacement.
2- Inject foundation crack with waterproof sealant.
3- Install aquablock.
4- Install 36in x 12in x 1/4in thk plate over the crack. Secure using 3/8in lag bolts. Inject holes with SIKA anchoring adhesive.
5- Repair/replace the parapet flashing to seal the roof properly.

Questions are:
1- How much spacing should I leave between each plate?
2- Is the plate thickness of 1/4in enough?
3- Anything else you would recommend?

Thanks in advance!

 

[Greenalleycat]

A picture would tell a thousand words here. If you've got a crack travelling 3 storys down a brick building and into a foundation then I would be very very careful with getting involved and making sure you were certain of what was going on before speccing a repair

Are you sure that the issue doesn't start in the foundations (bearing failure?) and go upwards into the parapet, rather than the other way round?

 

[struct101]

A picture would tell a thousand words here. If you've got a crack travelling 3 storys down a brick building and into a foundation then I would be very very careful with getting involved and making sure you were certain of what was going on before speccing a repair

Are you sure that the issue doesn't start in the foundations (bearing failure?) and go upwards into the parapet, rather than the other way round?

Agreed. Here is a picture. Let me know what you think.

I'm not sure this is bearing failure as this building has been standing since 1977... Also the bricks at various positions are damaged and in need of repairs especially near the parapet.

 

[ChorasDen]

What calculations have you performed to check the plate? You're asking us if the plate thickness is sufficient, but how have you confirmed that yourself?

 

[SWComposites]

Water leaks on a 12 story building roof gets all the way down to the foundation and causes a crack???
Is the foundation cracked due to external water logged soil pressure? (tension on the inside face).
Is the foundation cracked due to settlement?
Is it cracked due to some other effect or loading?
Need that sorted out before deciding on a repair.

Space between plates? which direction?

 

[ANE91]

1. The only thing that causes these types of cracks is restrained movement.
2. It’s good that you understand both the restraint as well as the movement. You wouldn’t be adding more restraint with something like a steel plate, right? And I bet the brick joints are just perfect.
3. Water can cause bricks to swell. So can the sun. In fact, bricks are their smallest fresh out the kiln. Maybe we need to be thinking about protecting the bricks from rain.
4. Without going through the dozens of other interconnected reasons that brick walls/veneers and concrete foundations move against restraint, I’ll assume that you’ve somehow established ongoing crack propagation, perhaps with a cheap crack gauge. How else could anyone know that the crack is growing?
5. Good thing you’ve ruled out foundation problems. Those are a pain. Running Shelby tubes is so expensive.
6. If you’re going with water from the roof, then that means you’ve followed ASTM E2128 and D7053, determining the water’s entry point, path of migration, and discharge. I hope you charged a lot of money for a comprehensive evaluation like that on a 12-story building.
7. I actually think the owner has a much bigger problem on their hands. For water to travel down that many stories, there must be a complete lack of weepholes and counterflashing. The owner will be happy to hear about this major issue you’ve discovered and helped them address, before it got worse.
8. I don’t see anywhere in your repair procedure measures to remove the pesky parapet. Best to demo it and save the owner the future headache. Better to replace all the bricks, too, cuz fresh ones aren’t degraded.
9. Make sure to slap that plate after install to make sure it ain’t goin’ anywhere.
10. Hire an engineer, in case my cheekiness didn’t land. Buildings have been known to kill people.

(OP is a contractor seeking free engineering services.)