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RE: Masonry Parapet Walls

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The disadvantages to removing and replacing the parapets are cost and the advantage of having the extra weight to help control rocking of the unreinforced masonry piers below (if you are doing a retrofit in accordance with UCBC Appendix 1 Chapter 1 or similar - RGA).
After the Northridge earthquake, the City of Los Angeles had developed criteria for the limits of wall deflection (if the wall is not plumb due to displacement by roof or floor joists).
You did not mention the thickness of the wall or if the "bulge" is in the exterior wythe of wall. I would tend to repair the section of wall by removing the outer wythe and replacing. If the displacement is within allowable limits, you might just consider injection grouting and trying to fill as much collar joint in the vicinity of the bulge. If there is sufficient collar joint coverage (50% or greater) this may not be require too much material that will be lost in the void space. This will help to lock the wythes.
Is there a header course in the area that bulges? I would assume that the bulge occurs between header course. If it occurs between header courses, it should be very easy to remove and replace the displaced bricks.
 
Finally, is the building retrofit? If not, I would seriously consider completing the retrofit in accordance with UCBC Appendix 1 Chapter 1. You might consider adding a concrete cap with reinforcing at the top of parapet. Remember to Key the concrete into the collar joint below. Then brace the parapet back to the roof.
 
It's been a good while since I have done a URM retrofit, check with your local building official to see if there are any special requirements for this repair. You might also want to check out the Emergency Measures published by the City of Los Angeles after the Northridge Earthquake and the Emergency Measures adopted by the City of Santa Monica. Both address wall and parapet displacement and provide the guidelines to determine if the displacement is within acceptable regions or not.
 
Regards
Dennis Wish PE
 
-----Original Message-----
From: Gilligan [mailto:littlebuddy(--nospam--at)bytheshore.com]
Sent: Sunday, June 14, 1998 9:09 PM
To: seaoc(--nospam--at)seaoc.org
Subject: Masonry Parapet Walls

Working on a project where the block & brick parpet wall is bulging at a line approx. where the timber joists bear. Wall is about 3 feet exposed to south, north facing, over 50 years old, old stone coping which leaked (has been repaired).  Generally all the criteria to have a troubled parapet wall and it is troubled. What is the fix for this wall? Remove and rebuild brick and block parapet? Any suggestions for remedy in the "fixed" wall.