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RE: Condition assessment for old brick walls

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Jordan,
A condition assessment of old brick walls is art and engineering. I would approach this with great caution unless you have experience yourself or can team with someone who has a lot of experience.

The location and age of the brick wall will often tell how it is constructed. There several good resources. The best is the 1904 book by Baker.

Common construction in the old days was to use pointing mortars on the outside wythes containing portland cement. The interior wythes would only only be lime, sand and water (no portland). The pointing mortars would confine the weaker (less expensive) interior mortars. Properly done, and maintained, these walls continue to be very strong. But what happened is that a lot of walls were sand blasted over the years and screwed up the pointing mortars. Water leaches in and flushes out the water soluble lime. Then you wind up with a stack of brick waiting for something to initiate a failure.

Strength determination can be done with "flat jacking". There is an ASTM on this now.

Re:
A Treatise on Masonry Construction by Ira Baker, 1904
Evaluation of Structural Properties of Masonry in Existing Buildings, National Bureau of Standards, 1974.
http://shop.store.yahoo.com/aberdeengroup/w-net04.html
http://www.historichomeworks.com/hhw/pbriefs/pb00-toc.htm
http://www.cr.nps.gov/hps/tps/briefs/presbhom.htm

I like to require match mortar with petrographic analysis to be done by one of the good labs like CTL, or Wiss Janney (Erlin Hime).

Properly restored masonry is a work of art and a thing to behold. Improperly done it is an abomination. Don't skimp on the homework.

Once you master this, try terra cotta and stone masonry restoration.

Regards,
Harold Sprague





From: "Jordan Truesdell, PE" <seaint1(--nospam--at)truesdellengineering.com>
Reply-To: <seaint(--nospam--at)seaint.org>
To: seaint(--nospam--at)seaint.org
Subject: Condition assessment for old brick walls
Date: Tue, 21 Mar 2006 10:52:55 -0500

I've got a building that is multi-wythe loadbearing brick, but (roughly) random portions of the bricks and mortar are in very poor condition. There are even a few bricks where you can grab a handful of red sand, and "excavate" more than half the brick with a finger. Similar condition with some of the mortar joints. The condition is primarily on the inner surface - I did not see any deterioration of this significance on the exterior. If I had to guess, I'd say 1% to 2% of the bricks, and maybe 2% to 4% of the mortar joints are no longer capable of supporting any type of load.

Any good references or recommendations on when a load bearing brick wall is considered "end of life" for a renovation project.

--
Jordan


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