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Re: Screen Anchors in Unreinforced Masonry

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One solution I used a number of years ago (at the suggestion of an epoxy
manufacturer) to remove steel bolts from a concrete block walls was to grease
the bolts prior to installation.  Once the temporary work was done, they were
easily backed out and the holes filled (in this case with more epoxy although
I would expect that one could use other materials).  

The project was to restore two layers of rigid insulation covered with plaster
over CMU walls in each of several large refrigerator boxes [20'x40'x18' high]
for a fish distributor.  The insulation had buckled inward about 18" at the
center of the walls when a fire damaged the refrigeration plant causing the
interior face to warm to ambient temperature while the face of the insulation
next to the CMU remained quite cold.  Since the client objected to the use of
steel bolts as a permanent fix due to long term heat transfer concerns, we
used temporary steel bolts (actually threaded rods) and strongbacks to draw
the insulation back in tight against the CMU.  Prior to installation, the
portion of the threaded rod to be embeded was greased with lube grease.
Plastic marine fender bolts with large diameter plastic washers (such as are
used in making dock flotation systems) were then installed as the permanent
restraint system once the insulation had been drawn tight against the walls.
The plastic bolts were anchored into the wall with epoxy.  

Although appearance wasn't critical (no one would see the finished work except
the fish handlers), the extent of visibility was a dot on the wall slightly
larger than the rod diameter (almost imperceptible).  This repair had the fish
distributor back in operation in about 7 days as compared to the approximately
8 weeks that would have been required by a more conventional remove and
replace process.  

I would think that with careful patching with a material colored to match the
brick, such a repair could be made to be hardly noticeable.

Bill Cain, SE
Albany, CA