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-   -   Widening an opening in a cinder block wall. (https://www.askmehelpdesk.com/showthread.php?t=401957)

  • Oct 2, 2009, 10:47 AM
    AmpleSound
    Widening an opening in a cinder block wall.
    Hello, I have a question about widening an existing opening in a cinder block wall. The wall itself is none bearing, but roughly 15 feet high. My client wants to open a doorway from current 3 feet, to 6 or 8 feet. I read something about "perpendicular cribbing" and support jacks, though I can't find anything on this particular support. Any help would be greatly appreciated. As far as lintel length needed, actual support system name, etc. We will be using a steel door frame as well. Any help will be greatly appreciated.

    Thanks!
  • Oct 2, 2009, 02:40 PM
    cyberheater

    It's cinder block? Is it a foundation wall?

    Where is it located? I hate to give advice on something without knowing more.
  • Oct 3, 2009, 08:59 PM
    21boat

    If this wall is non bearing and not retaining anything laterally then opening it up is fine with the following conditions.

    The removal of the block is to be looked at as an arch built in reverse. If there is enough side mass to sustain the arch above then all is fine.

    To understand the mechanics use a pencil to trace the new opening up the side jambs. Add another 8 " where the new concrete lintel will sit with min 4 bearing on new jambs. From there follow the bed and head joints like steps from each side until you get to the center of the New opening. That last block is the "Key Stone" which holds the rest of the block wall up without a Lintel. All of the block below that Keystone has the potential to fall out of the wall and hurt of kill.

    No bracing is required here if you have that natural arch and mass on it ends ( legs) to support the wall above that arch.

    Hears how we do this on the job site. Locate bottom of finish lintel height. Use a concrete saw and cut the block wall on the one side for lintel width to fit in wall and enough bearing on the sides to sit new lintel.

    Take a demolition hammer/brick hammer and knock out that one side of the block wall leaving the other side still intact.
    Knock enough block webs out to set new 4"x8" lintel. Don't forget to stuff a bag down the location on the jambs and mortar in to make a seat for the new lintel to set level on. Mortar in first lintel let cure. Now remove the other side of the wall that only has the 2' face left and some webs that's been your natural temporary support for those few blocks under that Keystone Block. Now you can remove all the block safely under the new lintel and no worries. If you use a longer lintel then you can now tooth the jambs back to lay new Jamb block for a nice finished opening
  • Oct 5, 2009, 07:24 AM
    dhatura

    The easiest way would be to get a new steel lintel. Use a diamond blade and cut the grout joint out where the last block will be for the headre spanning the 6' opening plus minimum 1' past on either side. You can throw a couple tapcons through the steel into the block if you'd like and then grout it back in. Mix a bonding agent and acrylic fortifyer with the morter. Afther it sets, you are free to remove any blocks needed without worry of blocks falling.
  • Oct 5, 2009, 08:31 AM
    AmpleSound
    Will this work the same if there is already a 3 foot opening in the wall?

    Quote:

    Originally Posted by 21boat View Post
    If this wall is non bearing and not retaining anything laterally then opening it up is fine with the following conditions.

    The removal of the block is to be looked at as an arch built in reverse. If there is enough side mass to sustain the arch above then all is fine.

    To understand the mechanics use a pencil to trace the new opening up the side jambs. Add another 8 " where the new concrete lintel will sit with min 4 bearing on new jambs. From there follow the bed and head joints like steps from each side until you get to the center of the New opening. That last block is the "Key Stone" which holds the rest of the block wall up without a Lintel. All of the block below that Keystone has the potential to fall out of the wall and hurt of kill.

    No bracing is required here if you have that natural arch and mass on it ends ( legs) to support the wall above that arch.

    Hears how we do this on the job site. Locate bottom of finish lintel height. Use a concrete saw and cut the block wall on the one side for lintel width to fit in wall and enough bearing on the sides to sit new lintel.

    Take a demolition hammer/brick hammer and knock out that one side of the block wall leaving the other side still intact.
    Knock enough block webs out to set new 4"x8" lintel. Don't forget to stuff a bag down the location on the jambs and mortar in to make a seat for the new lintel to set level on. Mortar in first lintel let cure. Now remove the other side of the wall that only has the the 2' face left and some webs thats been your natural temporary support for those few blocks under that Keystone Block. Now you can remove all the block safely under the new lintel and no worries. If you use a longer lintel then you can now tooth the jambs back to lay new Jamb block for a nice finished opening

  • Oct 5, 2009, 07:15 PM
    21boat

    Quote:

    Will this work the same if there is already a 3 foot opening in the wall?
    Yes if the wall is min 8" wide/thick As far as my Geo concrete pre formed lintels come 4" or 6"' wide by 8" high and whatever lengths up to a garage door opening. So, if you have standard lintels at that door opening now they should be in two pieces each at 4" thick.

    Now for some crazy reason thats a 6" wide wall then one lintel will be there at 6" wide. If the wall is 10" thick then one lintel will be 6" wide and its sister lintel will be 4" wide.

    Even a 6" wide wall you can remove that 6" thick lintel all together and it being only a 36" wide door there now that 3' total removal will only possibly release a couple of block and threat the rest of the wall as I stated above. A Keep in mind the Arch effect, and anything inside that arch can fall but usually it doesn't simple because of the tight block header joints.

    As a reminder the arch needs enough meat on its side legs to maintain that arch. I say this since you never mention how much wall is left on each side of the new opening.

    If you have some funky block we take a 2by 4 horizontally above the diamond blade cut tap con that 2by on that course and another one above the arch point same length. Now add some uprights 2by flat over both horizontal to upper 2 by screw in. This helps hold the block inside that arch area from falling
  • Oct 5, 2009, 07:52 PM
    21boat
    Dhatura. I wanted to point out the main part of the question was how to Support the wall Before anything is put in for a lintel.

    Quote:

    the easiest way would be to get a new steel lintel.
    What do you mean by Steel Lintel? If this is an angle iron then how do you propose to get that back of the upright angel in the web areas? If your "lintel" is flat steel then its structurally bad.
    A steel lintel in this application is also a bad marriage not to mention expensive.

    1. First off that steel lintel needs to be gaged on its thickness to meet code, could require an engineered stamp for code acceptance. Pre formed Concrete lintels are to code on the get go at this length.
    2. Second you have a less finished wall simply because you need to lay popcorn brick to fill in the inside ( I ) area for a finish look.
    3rd since metal and mortar hasn't high adhesion qualities there needs to anchor bolts at the I beam ends to compensate for that steel to mortar marriage.
    4th More so then not the bottom of the I beam needs an added welded flat steel plate to act as an Angle iron ledge to lay ( cement brick ledge) for a finished look.
    So the all in all the "easiest way " is not cheap in this case.

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