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  1. #1
    Chris Imo's Avatar
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    Default Concrete block wall- I want to make sure is done correctly by contractor

    Hello all

    I have a contractor coming by to build a concrete block wall( 6 feet tall) & concrete block (2 feet tall) with wrought iron on top. My biggest concern as a home owner is figuring out if he is doing any shortcuts to safe materials or money...I just want to make sure this wall will last a very long time. I understand that concrete will always crack one time or another...but how do I make sure the footer is done correctly, should the concrete blocks should be filled with concrete?, what about the type of rebar for footer and how deep should it be and lastly...how do I make sure the wrought iron fence that goes on top of the 2' concrete block wall is going to be secure and will not become loose over time since if will only be fastened with screews on top of concrete caps.

    I am open to ALL suggestions...just a concerned home owner...thanks in advance

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  2. #2
    Join Date
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    Default Re: Concrete block wall- I want to make sure is done correctly by contractor

    Footings - on a 8" CMU wall, typically 18" wide. I don't know anything about seismic or soil conditions in Texas so depth and sizes could be all wrong for your area.
    Rebar- typically #4 or #5, into footing and up into wall. At least the 1st course should be fully grouted. Depending on local requirements it could be 2-3. I would recommend at least 2-3 on a free standing wall. Rebar should go all the way up to the top. Depending on conditions and length a bond beam might not be a bad idea either.
    Railing - installation all depends on how much action you think the railings will get. If in a location without kids, balls, or jumping dogs, etc. just bolt them down. If these are heavy railings that might see some activity, consider ordering longer legs, extending the legs into the CMU with grout and cutting the caps around the legs. There other considerations but ...
    You are essentially asking someone to design your wall. In order for that to work it should be a licensed professional in your area who understands ground conditions.
    This is an easy enough job. Doing it right so that the wall can't just be pushed over requires some forethought and engineering.
    Don't accept a 1 page proposal with little details. Get multiple bids. Also check what local requirements are. There may be height and design limitations.
    If using modern limestone for capping make sure a membrane is installed between the wall and cap. What's your weather like, lots of rain? if so, then grading and CMU protection are another issue. Are you going to paint the CMU or leave it raw?
    You should hire someone locally to help with proper design.

    www.aic-chicago.com
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  3. #3
    Chris Imo's Avatar
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    Default Re: Concrete block wall- I want to make sure is done correctly by contractor

    Thanks for your reply Markus

    I was planning to grade away from the wall ( some areas I have to raise the grade 1' for properly drainage).....I am planning to build a dry creek bed to address the drainage issue thus bringing the water level below the fence level

    The CMU should have stucco finish......it doesnt really rain here in texas that much, but when ir rains...it pours like crazy.


  4. #4

    Default Re: Concrete block wall- I want to make sure is done correctly by contractor

    Your local Bld. Dept should tell what they require, around here it is 1 foot deep for every 1 foot of wall!! (typical)


  5. #5
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    Default Re: Concrete block wall- I want to make sure is done correctly by contractor

    I am presuming that you are referring to a retaining wall with a guard on top consisting of a 24" high block wall topped with a railing.

    First and foremost, have the contractor draw it up, submit it to the local building department with the permit application, and then build it as it is permitted.

    There are many things to consider with a concrete block wall with unbalanced fill heights (i.e., the earth is lower on one side, the wall goes up, there is fill on the other side of the wall with lawn, deck, or concrete on it).

    There are specific minimum code requirements depending on the unbalanced fill height, the type of soil, the width of the block (8" or 12"), the spacing of the filled cells with steel and the size of the steel.

    Marcus hit some of the high points, but I would recommend you have an engineer design it and provided signed and sealed drawings.

    Jerry Peck, Construction / Litigation Consultant
    Construction Litigation Consultants, LLC ( www.ConstructionLitigationConsultants.com )
    www.AskCodeMan.com

  6. #6
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    Default Re: Concrete block wall- I want to make sure is done correctly by contractor

    Concur with all who advocate Eng/Design services, for the stucco, the wall needs to be better built than normal, if you want to minimize cracking. Remember, you are applying a brittle material to a monolithic surface. Any movement will crack both the block and the stucco over it.

    I'm a dyslexic agnostic-Don't believe there is a dog...

  7. #7
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    Default Re: Concrete block wall- I want to make sure is done correctly by contractor

    Quote Originally Posted by John Carroll View Post
    Remember, you are applying a brittle material to a monolithic surface.
    That is not a monolithic surface, that wall is made of individual block and mortar joint.

    A poured concrete wall is a monolithic surface.

    Any movement will crack both the block and the stucco over it.
    That I agree with.

    In Florida we build basically the same way they do in Texas except that in Texas the slabs are held together with post-tension tendons, while in Florida the slab is left free to crack and separate.

    Sure we have steel in the footings, in the filled cells, and in the bond beam (most of Florida does not do poured tie-beams like South Florida does), but when the earth settles - as it does - the house moves, and, with no post-tensioned tendons to keep it together are it moves ... it cracks.

    Sometimes it cracks and then cracks again, sometimes not. The home inspector is put in the position of knowing their area and knowing when to call for the structural engineer and knowing when that is not needed. And, yes, that does bring with it a great potential for liability for the home inspector who makes the call to not call the structural engineer when it turns out that the structural engineer was needed. The other option is to ALWAYS call for the structural engineer because that type of cracking is so prevalent here ... in which case the home inspector would be blacklisted and their business would eventually dry up - sure, they would continue to get some referrals, but not a lot, even the clients expect the home inspector to know their area and when to call 'em, when to fold 'em, and when to walk away ... never count your money at the table ... (Kenny Rogers)

    Jerry Peck, Construction / Litigation Consultant
    Construction Litigation Consultants, LLC ( www.ConstructionLitigationConsultants.com )
    www.AskCodeMan.com

  8. #8
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    Default Re: Concrete block wall- I want to make sure is done correctly by contractor

    Never one to disappoint, JP. Nice to hear you're still kickin'.

    I'm a dyslexic agnostic-Don't believe there is a dog...

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