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RE: Adding Storefront to Existing CMU Wall

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I did nearly exactly this at a grocery store remodel a few years back.  I don’t recall the exact detailing, but we huddled with the engineer and came up with a pair of sandwich channel beams which were bolted together through the existing wall just above the line of the header, a wall saw cut a series of 2 ft wide sections of wall out and new steel columns were installed that had a top plate that spanned to the two channels on each side.  This allowed us to be able to support the wall with the needle beam detail you describe  only at the new footing locations, then demolish the existing footing and pour new pads with the A.Bs already installed into the column base plates.  The real trick was to ensure that the channels on each side had their bolt holes aligned precisely enough.

 

You did not describe it, but I add that this was an interior wall, so the channels on each side were exposed and nobody cared.  If its on the exterior, you may have to have the architect design a cover for the exterior channel.

 


From: Rich Lewis [mailto:seaint04(--nospam--at)lewisengineering.com]
Sent: Tuesday, November 13, 2007 8:08 PM
To: seaint(--nospam--at)seaint.org
Subject: Adding Storefront to Existing CMU Wall

 

This post is associated with my other Walmart post.  I’m working on designing the framing to put in storefront windows and was wondering how others had tackled it.

 

I have an 18’-8” high bearing wall.  It is 12” CMU and 4” brick.  I have no drawings so I don’t know if it is partially reinforced or not.  All the holes that were poked in the wall showed hollow cores so far.

 

The owner wants to put a storefront strip window 9’-0” high the length of the building.  About ½ the length of the wall has steel beams and columns supporting the roof framing.  Some sections have just a masonry bearing wall. 

 

I have given some thought as to how to support the wall.  I’m considering using a 16”x?” tube lintel to carry the 16” wide wall.  I haven’t sized it yet so I don’t know the height.  I will have steel posts directly below the tube header, probably at 15’ on center.  I will have some type of ‘strong back’ column behind this to provide the lateral support of the wall from foundation to roof framing.

 

Construction sequencing as I see it is to cut a hole at the floor line to install the column footing.  I see the wall being able to arch over the hole cut for the footing.  I then see wood needle beams poked through the wall above the steel header to support the wall while the section below is demolished.  The new header and posts would be installed.  Steel shims would then be wedged between the tube beam and the masonry to load the beam as much as possible before releasing the needles.  A non-shrink grout needs to be packed in the gap made by the shims.

 

My preference is to see this done a section at a time, whether 15’ or 30’ lengths.  I know what will happen though is any contractor who is doing this will want to shore it all up at once and tear it all out at once and install the steel framing.

 

I’m looking for critique or suggestions as to what I have proposed.  Any steps left out?  Any suggestions to improve on what is proposed?

 

Thanks.

 

Rich