small piece of wall fell off and metal exposed on exterior

Discussion in 'Walls and Ceilings' started by qmqmqm, May 23, 2015.

Help Support House Repair Talk by donating:

  1. May 23, 2015 #1

    qmqmqm

    qmqmqm

    qmqmqm

    Well-Known Member

    Joined:
    May 3, 2012
    Messages:
    87
    Likes Received:
    9
    Hi everyone.

    A small piece of wall fell off beside my garage door. The piece that fell off is about the size of a thumb.

    I see that some metal is exposed. Not sure what the metal is for, but it's rusting. Please see pictures enclosed.

    Does anyone know what the metal is for?

    Does anyone have any suggestions as to the cause of the piece of wall falling off, and how I can do a proper repair? If I just patch the spot with concrete, I'm worried that the metal will just continue to rust underneath...

    Cheers!

    Paul

    20150509_152458.jpg

    20150509_152453.jpg
     
  2. May 23, 2015 #2

    CallMeVilla

    CallMeVilla

    CallMeVilla

    Well-Known Member

    Joined:
    Feb 9, 2010
    Messages:
    1,657
    Likes Received:
    597
    Looks like the rebar (pronounced "ree-bar") in the form used to build your garage. Rebar always rusts inside walls. This is a concrete pop, nothing serious. You can get some Cement-All and patch the pop. Enjoy Memorial Day and the soldiers who paid for our freedom!
     
  3. May 24, 2015 #3

    joecaption

    joecaption

    joecaption

    Well-Known Member

    Joined:
    Jan 8, 2011
    Messages:
    2,294
    Likes Received:
    380
    Just be aware any patch is going to stick out far more then that tiny rusted spot.
     
  4. May 25, 2015 #4

    nealtw

    nealtw

    nealtw

    Contractor retired

    Joined:
    Nov 4, 2010
    Messages:
    24,661
    Likes Received:
    3,337
    Location:
    Chiliwack BC Canada
    I hate to say it but wrong.

    Rebar will rust only when air and water can both come into contact with. It should never be closer to any surface than 2" for that reason. When it does rust like this it expands and fractures the concrete.
    [ame]https://www.youtube.com/watch?v=peAEMydbJts[/ame]
    Drill into the rebar about 2" clean out as much steel as you can and patch the concrete.
     
  5. May 25, 2015 #5

    mako1

    mako1

    mako1

    Junior Member

    Joined:
    Mar 23, 2014
    Messages:
    131
    Likes Received:
    46
    I hate to say it but wrong again.I did ironwork for 12 years when I was younger and all rebar is specked to be 3/4" from the slab edge.
     
  6. May 25, 2015 #6

    nealtw

    nealtw

    nealtw

    Contractor retired

    Joined:
    Nov 4, 2010
    Messages:
    24,661
    Likes Received:
    3,337
    Location:
    Chiliwack BC Canada
    http://www.concreteconstruction.net/concrete/placing-reinforcing-steel.aspx
    Minimum concrete cover
    For concrete cast against and permanently exposed to earth (such as footings): 3 inches
    For concrete exposed to weather or earth (such as basement walls)
    #6 bars and larger: 2 inches
    #5 bars or smaller: 1½ inches
    For concrete not exposed to weather or in contact with ground:
    Slabs, walls, and joists: #14 and #18 bars: ½ inch
    Slabs, walls, and joists: #11 bars and smaller: ¾ inch
    Beams and columns: 1½ inches
     
  7. May 25, 2015 #7

    CallMeVilla

    CallMeVilla

    CallMeVilla

    Well-Known Member

    Joined:
    Feb 9, 2010
    Messages:
    1,657
    Likes Received:
    597
    Well, we got a professional "throw down" here ! :D

    Honestly guys, all of us are right to some degree. While the spec calls for rebar to be 2" away from the outside, we have a situation here where it is clearly closer. It rusted, it popped the cement. Now, I was trying to give the happy DIYer some easy ideas without calling in a demo crew. Drilling out 2" of rebar could be really challenging to Mr. Harry Homeowner. A simple Cement All fix seemed enough.....

    Would it be uneven? Probably, that is how first time DIYers start to learn troweling skills.
    Could it pop again in the future? Yes, freeze thaw sucks.

    Enjoying the give-and-take. :D
     
  8. May 25, 2015 #8

    qmqmqm

    qmqmqm

    qmqmqm

    Well-Known Member

    Joined:
    May 3, 2012
    Messages:
    87
    Likes Received:
    9
    Thanks everyone for the suggestions!

    If I simply patch up the concrete, wouldn't the rebar continue to rust inside? Would that cause more problems inside the wall? Or is the rusting process so slow that I shouldn't worry about it?

    Cheers,

    Paul
     
  9. May 26, 2015 #9

    nealtw

    nealtw

    nealtw

    Contractor retired

    Joined:
    Nov 4, 2010
    Messages:
    24,661
    Likes Received:
    3,337
    Location:
    Chiliwack BC Canada
    Depends on what it is. If it is running sideways or up and down, this might only be the beginning as the rest of the bar might be as close as this peice. If the foundation turns right there is might be just an end of a peice running into the garage. The video is the only fix I know.
     
  10. Jun 1, 2015 #10

    slownsteady

    slownsteady

    slownsteady

    Administrator Staff Member Admin Moderator

    Joined:
    Jun 6, 2009
    Messages:
    6,872
    Likes Received:
    1,284
    Location:
    Sussex County, NJ
    You can find a rust stopper in spray cans usually on the shelf in automotive stores. Wire brush the exposed spot and spray it with this stuff. It reacts with the remaining rust to stop oxidation. The stuff turns black, so protect your work area before spraying. Then make the concrete repair.
     
  11. Jun 2, 2015 #11

    mako1

    mako1

    mako1

    Junior Member

    Joined:
    Mar 23, 2014
    Messages:
    131
    Likes Received:
    46
    Neal: Not trying to argue here.I was the superintendent for a ironworking company in FL for 12 years doing the ironwork on many 10-25 floor structures including bridges which included the Sunshine Skyway bridge over Tampa Bay.
    I have to admit that I have never read any code books or papers on either concrete or rebar.Well,maybe a little.
    Every job that we did had a engineered set of drawings. And was inspected by a structural engineer so no need to know anything accept to build by the plans for that particular job.I would say that 99% of these structural drawings call for 3/4" clearance between rebar and edge of concrete .Either in slabs,coloumns or walls.
    Even in this salt water environment .
    Just my experience in the trade.
     
  12. Jun 3, 2015 #12

    nealtw

    nealtw

    nealtw

    Contractor retired

    Joined:
    Nov 4, 2010
    Messages:
    24,661
    Likes Received:
    3,337
    Location:
    Chiliwack BC Canada
    Fair enough, we all work from experience. Mine is any concrete work we prepare like footing, foundation, stairs, sidewalks, driveways and now garage floors. Any rebar closer to any surface than 2" will fail by the city and engineers.. We don't have to argue the picture above is enough for me.
    There is a reason for epoxy coated rebar in bridges latley???????
     
  13. Jun 3, 2015 #13

    slownsteady

    slownsteady

    slownsteady

    Administrator Staff Member Admin Moderator

    Joined:
    Jun 6, 2009
    Messages:
    6,872
    Likes Received:
    1,284
    Location:
    Sussex County, NJ
    maybe a difference in regulation 'tween the two locations?????
     
  14. Jun 3, 2015 #14

    nealtw

    nealtw

    nealtw

    Contractor retired

    Joined:
    Nov 4, 2010
    Messages:
    24,661
    Likes Received:
    3,337
    Location:
    Chiliwack BC Canada
    different application, for sure.
     
  15. Jun 3, 2015 #15

    slownsteady

    slownsteady

    slownsteady

    Administrator Staff Member Admin Moderator

    Joined:
    Jun 6, 2009
    Messages:
    6,872
    Likes Received:
    1,284
    Location:
    Sussex County, NJ
    Arrrgh. Tampa Bay doesn't get mentioned in NY / NJ after last friday.:mad:
     
  16. Jun 3, 2015 #16

    nealtw

    nealtw

    nealtw

    Contractor retired

    Joined:
    Nov 4, 2010
    Messages:
    24,661
    Likes Received:
    3,337
    Location:
    Chiliwack BC Canada
  17. Jun 3, 2015 #17

    GeselleBrian

    GeselleBrian

    GeselleBrian

    Member

    Joined:
    May 31, 2015
    Messages:
    15
    Likes Received:
    2
    You don't have to de-rust it, but the reason it's popped off is because it has rusted (kind of contradictory, I know)

    The reason is, the alkalinity in the cement prevents rebar from rusting any further--provided IS still alkaline (cement neutralizes reacting with CO2 in the air).

    The official way to treat something like this is to hammer off all neutral cement until you arrive at cement that is still alkaline enough. Minimum is pH 12, if I'm not mistaken. To test you need indicator fluid.

    BUT as this spot is not likely to weaken the statics of your garage, I would just fill it with new concrete.

    The neutralization process mentioned is called carbonatization. Happens to all concrete over time, as far as I know.
     
    Last edited: Jun 3, 2015
    nealtw likes this.

Share This Page