Presidio Chapel Historic Structure Report - Presidio Trust

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HISTORIC STRUCTURE REPORTFINALSTAINED GLASS RECOMMENDATIONS *Existing ConditionsThe stained glass windows of the main chapel are approaching the end of thelife cycle of the connective materials. All of the windows exhibit problemsranging from out-of-plane portions to severe buckling, and several windows arein failure with severe buckling and deterioration of metals. There is very little, ifany, broken glass, but this is a real threat with such severe warping and bending.Over time, the materials of leaded glass windows are naturally susceptible todeterioration that affects structural integrity, waterproofing capacity, and thequality of light transmission. Among the causes of window deterioration areoxidation, wind pressures, gravity loads, and airborne particulates.Oxidation of the lead and soldered joints weaken the structural integrity ofsupports for the glass pieces. Over time, a layer of oxidized material developson the surface of the metals due to continued atmospheric exposure. Since the<strong>Presidio</strong> is located in a marine environment, additional corrosion of the metalsmay be caused by airborne salts.Varying wind pressures cause flexing of the panels, which leads to fatigue of thelead, joints, and connections to supports. The flexing and oxidation combine todeteriorate the cementious water-caulking material, thus opening pathways forwater infiltration to the interior and adversely affecting the frames, structure andfinishes of the chapel.The structural integrity of the windows is affected by gravity loads on lead, apliable metal that, although supported, stretches and bends over time.Environmental airborne particulates collect on the exterior surfaces, and residuesfrom oil and wax fumes accumulate on the interior surfaces. These accumulatedmaterials greatly reduce the amount and quality of light coming into the chapeland may cause the exterior surface to become pitted over an extended period oftime. Lower light volume and quality can make the art content of the windowsdifficult to distinguish, and the colors may be perceived as dull.Currently there is no known vandalism to the windows. Unexpected openingsfrom vandalism may weaken the surrounding connections, create a direct pathfor water, and make neighboring windows difficult to see due to adjacent brightareas. Some urban churches install transparent plastic shields outside stained glasswindows to prevent damage from vandalism.RecommendationsIt should be a priority to have the windows releaded, grouted and cleaned inthe next ten years. The most severely deteriorated windows should be restoredimmediately. This could prevent breaking of glass, material damage to thestructure and finishes of the building, and diminution of the chapel’s aesthetics.Most of the windows will require restoration by the end of this decade due toincreasing fragility.If financially feasible, it would be most efficient to restore all the windows atonce when the general contractor’s scaffolding and site protection are in place.Restoration at this time would also take advantage of on-site constructionpersonnel who would have the skills and materials available to address anyhidden building fabric issues that may be revealed during the removal of thewindows. Additionally, with the building expansion and the addition of a suite ofnew windows, presenting the stained glass windows as unifying elements of thebuilding would contribute to a successful project.Restoration should be undertaken before a majority of the windows begin tosignificantly fail. Restoration work should include documentation of existingconditions, removal of panels to a stained glass studio for cleaning, installationof temporary infill panels of glass or other weatherproof materials, releading,grouting, and preparation for reinstallation. Panels should be reinstalled inoriginal locations, securely attached to the building structure and installed to bewaterproof.An opinion verbally delivered by Reflections Studios in 1999 stated thatthe windows should be releaded within 20 years. This report supports thatrecommendation.124MARCH 2012
PRESIDIO CHAPEL (BUILDING 130)SAN FRANCISCO, CALIFORNIAStained Glass Window Recommendations and EvaluationRecommendationsIf work is postponed for ten to fifteen years, windows most at risk face significantdamage to the panels and the building fabric, resulting in more extensive repairs.Other windows will continue to deteriorate and become more at risk of failure.With postponement beyond the building project, the opportunity to use in-placeconstruction scaffolding and personnel would also be lost.1. Restore failing windowsFully restore the three windows in the apse. For each window, budget $8,900for restoration and $600 for additional paint restoration if needed (to bedetermined upon closer inspection).2. Restore windows at riskFully restore windows at risk. These are the windows in the clerestory andseveral on the main floor. For each clerestory window, budget $13,100for restoration and $750 for additional paint restoration if needed (to bedetermined upon closer inspection).MURAL CONSERVATION AND TREATMENT RECOMMENDATIONS *Title: <strong>Presidio</strong> MuralArtist: Victor Arnautoff, 1935Subject: Early history of California, religion, and activities of the armyin 1935, occupied with development of science, radio, andengineering of the Golden Gate BridgeLocation: East portico wall, now enclosedPatron: SERA, State Emergency Relief AdministrationMedium: Buon frescoSize: 10’4” x 35’ 5 ½” (+/- ½” each dimension), above woodenwainscotingThe conservator examined the mural under normal ambient daylight and 500wtungsten photographic light. Magnification was provided by a 1.75x head loupe,and access was supplied by an eight-foot ladder. Glass shields at the bottom edgeof the mural were left in place during the examination, as was a large desk at thecenter of the wall. Most of the mural surface was accessible, with the exceptionof the center and the top two to three feet.Fully restore main floor windows (101, 102). For this group, budget $12,850for restoration and $500 for additional paint restoration if needed (to bedetermined upon closer inspection).3. Refurbish two windows in bell tower. These will require restoration but notreleading.SupportThe mural has all the characteristics of buon fresco. Traditionally, there is anarricio (scratch layer) over which is laid one or more finish coats (the intonaco). Itis not known whether or not a sinopia drawing (typically in red earth) exists on thearricio, but it is presumed to be. Photographic archives of frescoes in process atCoit Tower, finished the previous year, show the sinopia layer in the work of theartists there. Arnautoff and some of the assistants listed on this fresco worked atCoit Tower; they likely constructed this fresco in the same way. There are no lossesto the fresco that reveal the stratification and thickness of the plaster layers.PART IV: APPENDIXPage & Turnbull125
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Presidio Chapel Historic Structure Report - Presidio Trust

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