Sandstone Patching and Repair -- Los Angeles, CA

Los Angeles, Los Angeles County,
California, USA

Originally part of a wealthy neighborhood near historic downtown Los Angeles, this home eventually became part of the eastern campus of Mt. St. Mary’s College. Clad in sandstone originally quarried near Santa Barbara, it had undergone severe decay and material loss. Sandstone patching and repair with specialty repair mortars provided the means to bring it back to a higher level. This involved creating a mold of a generic pitch-faced sandstone block from an un-deteriorated portion of the facade. This allowed us to recreate accurate and visually consistent replacement units.

Wikipedia Reference:

http://en.wikipedia.org/wiki/Mount_St._Mary’s_College

Click on images below to enlarge.

Restoration of the sandstone veneer on this former residence called for use of color-matched repair mortars.
Over 100 blocks were cut back approximately 1-2″ in depth to remove the deteriorated face material. This approach allowed us to repair the veneer and surface appearance of the building skin without removal of the entire range of structural components. Minimal intrusion is always an important criterion in our assessment of possible restoration alternatives.
Utilizing the Jahn repair mortar for sandstone and limestone, we created a mold of a generic pitch-faced sandstone block from an un-deteriorated portion of the facade. This allowed us to re-create accurate and visually consistent replacement units.
Here the replacement units are laid out in anticipation of installation on top of the original sandstone blocks where deteriorated material has been removed.
In this image, the new fascia units fabricated from the specialty repair mortar have been installed over the base of prepared original material. All that remains is to install the matching joint mortar.
We can now see a close approximation of the original surface as it appeared prior to weathering and degradation.
This column supporting the porch roof had undergone a similar pattern of decay despite its relative lack of exposure to the elements. Degradation of masonry elements in such an unexposed area of the structure is a likely indication that the characteristics of the originally-used sandstone were not conducive to use as an exterior cladding material, even in a benign climate such as Southern California’s.
Again, our recreation of the original ‘look’ of the stone veneer is as close as possible to the appearance when new. It is also much more dimensionally and environmentally stable, since the normal weathering forces of abrasion and acid rain will have significantly less effect on the surface of the new restoration mortar used.
It is important to note that our repaired area shown here is approximately 50% replaced surface material.Because care was taken to ensure that replacement material would visually blend with original material, we have managed to produce a result that is entirely consistent with the original appearance of the structure when built. This is congruent with our constant mantra of quality: ” Our work should be invisible wherever possible”.
There are several other former residential structures on the campus of Mt. St. Mary’s College that will hopefully receive similar treatment over the next few years. Preserving this time-capsule of earlier Los Angeles residential architecture is a worthy ambition for the school.