A06_Specifications_HAFE_Bldg38_UpdatedConditionsAssessment2021_Final_1.pdf

Updated Exterior Stucco Condition Assessment and Treatment Recommendations for

Building 38 – Tearney Building at

Harpers Ferry National Historical Park

Harpers Ferry, WV

August 2021

Prepared for:

Mia Parsons

Darlene Hassler

Peter Dessauer

Harpers Ferry National Historic Park

Harpers Ferry, WV

Prepared by:

Courtney Magill

NCA Architectural Conservator

Introduction

On May 25, 2021, NCA Architectural Conservator, Courtney Magill, and NCA NCPE Architecture Intern, Sara Patrick,1 visited Building 38 – Tearney Building to assess the current conditions of the exterior plaster on the rear, northwest face of the building. The purpose of the site visit was to provide Harpers

Ferry National Historical Park with an updated conditions assessment and treatment recommendations for PMIS 246165 – “Preserve Tearney Building Historic Exterior Stucco in Lower Town Harpers Ferry.”

The goal of this document is to update the findings of the previous conditions assessment by former

NCA Architectural Conservator, Lindy Gulick, in 2018 and provide the current condition of the plaster, an abbreviated scope of work, and treatment recommendations that can be used to supplement the existing PMIS statement.

The recommendations for treatment in this document are based on:

Park Service, Technical Preservation Brief, Preservation Brief #22 The Preservation and Repair of Historic Stucco (https://www.nps.gov/tps/how‐to‐preserve/briefs/22‐stucco.htm)

The Secretary of the Interior’s Standards for the Treatment of Historic Properties (https://www.nps.gov/tps/standards.htm)

National Park Service, Historic Structures Report‐ Building 38, October 1982, prepared by Susan L. Shufelt, National Capital Team, Denver Service Center.

Exterior Stucco Condition Assessment and Treatment Recommendations for Building 38 – Tearney Building at Harpers Ferry National Historical Park, Harpers Ferry, WV, September 2018, prepared by Lindy Gulick, Architectural Conservator, National Capital Area.

Historic American Building Survey, Tearney Building, 1964, drawing set prepared by John E.

Donaghey

The wall was observed visually and acoustic sounding (lightly tapping with the flat of a fingernail and one knuckle to listen for changes in tone) was performed on all parts of the plaster that were within reach.

The sounding was used to determine the presence of voids and detachment of the plaster from the substrate along the wall. Certain areas of the plaster surface were not available for acoustic sounding testing due to limited reach from the onsite ladder on the porch or access blockage by extant building elements, such as the back porch infrastructure and interpretive signage. The areas where acoustic sounding was not performed are called out in Figure 1. Material testing and analysis was not performed on the exterior stucco or plaster.

1 Both on the NCA Preservation Services Team lead by Julie McGilvray.

Figure 1. Red hatch indicates areas of the northwest wall where acoustic sounding was not able to be conducted due to access issues.

For clear documentation of conditions on the wall surface, a northwest elevation from a 1964 HABS documentation drawing set was adapted by Sara Patrick to reflect the current state of the building. This modified elevation was then used for conditions documentation in the field (Appendix I).

Rationale for Conservation

The rationale for the treatment of the extant material on the rear wall of the Tearney Building is based on the Preservation treatment approach of the Secretary of the Interior’s Standards: “applying measures necessary to sustain the existing form, integrity, and materials of an historic property. Work, including preliminary measures to protect and stabilize the property, generally focuses upon the ongoing maintenance and repair of historic materials and features rather than extensive replacement and new construction.”2 The goal of this project is to conserve as much historic fabric as possible in place on the rear wall of the Tearney Building. This means that all extant plaster/stucco material should be stabilized and retained even though a large majority of the wall’s surface finish has been covered in various repair campaigns; removal of these surface repairs would likely result in great loss of the historic fabric underneath.

Brief History and Past Treatment

An in‐depth conditions assessment of the exterior plaster of Building 38 weas completed by former NCA

Architectural Conservator, Lindy Gulick in September 2018.3 For the purposes of providing an up‐to‐date conditions assessment, this report referenced the earlier report and provides an update to conditions and recommendations that were prescribed for the purposes of informing an upcoming treatment for the building’s external plaster.

2 The Secretary of the Interior’s Standards for the Treatment of Historic Properties, https://www.nps.gov/tps/standards.htm, page 27.

3 Exterior Stucco Condition Assessment and Treatment Recommendations for Building 38 – Tearney Building at Harpers Ferry National Historical Park, Harpers Ferry, WV, September 2018, prepared by Lindy Gulick, Architectural Conservator, National Capital Area.

The rear wall of the Tearney Building displays a few areas of architectural ghosting that indicate the first‐ floor level rear yard area was formerly used as a set of small rooms. The existence of these rooms (Rm.

104 and 102) can be both seen in section (Figure 2) in the HABS drawing set from 1964 and inferred from the rear elevation from the same drawing set by the lack of the first floor in the drawing (Figure 3).

At some point between 1964 and the 1982 HSR this set of rooms was removed however, as can be seen in the 1981 image from the Report (Figure 4). Records indicate that the Tearney building was restored by the National Park Service by 1990 (likely the majority of the work was begun in 1984‐85 and completed by the end of the decade), and this is when the current building evolution of a second‐floor porch and a rear yard came into being.

Figure 2. Transverse section facing NE of the Tearney Building from the 1964 HABS Drawing set. Note the rooms on the lower level at the rear of the building rather than the open‐air configuration that is extant today.

Figure 3. Rear elevation of the Tearney Building from the 1964 HABS Drawing set. Note that the first level of the building is not drawn because it is below “street” level at this point and the lower‐level doors open into rear rooms.

Figure 4. Rear elevation as seen in the 1982 HSR on the Tearney Building. Note the lack of the current porch (indicated by red arrows) before the NPS restoration project, beginning in the mid‐1980s and finished by 1990, restored the building.

Architectural ghosts on the first floor of the rear that remain from this change in building use and appearance include the general lack of finish plaster on the wall at the northeast end; the plethora of doorways; and the sharp delineations, discolorations, and holes in the scratch coat and finish coat that appear to mark wall divisions.

There is likely a lack of finish plaster at the northeast end of the first floor because these walls would have originally been interior walls and so the plaster would not have been treated and maintained in the same way as that of an exterior wall. Thus, having a less hardy finish, it likely disintegrated more quickly when exposed to weathering upon destruction of the rear rooms, leaving patches of the scratch coat, and exposing the structural masonry of the building (Figure 5). The remaining scratch coat has likely continued to disintegrate off the wall with rising damp and other water exposure, as the larger remaining portions of the scratch are concentrated towards the top of the first floor (Figure 6).

Figure 5. Area to the right of the northwest door on the first floor showing detail of remaining scratch coat on masonry walls with small sections of finish coat still adhered in areas.

Figure 6. Northeast section of the first floor wall showing 95% loss of finish plaster but sections of scratch coat still remain, concentrated towards the top of the wall out of reach from rising damp and under the protection of the porch. These areas were more than likely interior walls originally. Note that intact area in the far northeast corner is skim coated in cementitious material.

The height and width of the windows and bricked in area and their positioning on the wall (especially considering the position of the windows sitting at least 1‐2 feet above floor level on the second floor), suggest that they were likely doorways into the smaller rooms originally in addition to the extant doors.

The HABS elevation shows an exterior staircase leading down from the second floor to the first, and likely the northwest doorway was either also another rear room door or an exterior doorway. A note on the rear elevation drawing implies that the northwest tall window may have originally been part of the passage leading to Shenandoah Street (Rm. 105) (Figure 3).

A sharp delineation in the scratch coat can be seen towards the top of the wall between the northeast door and the middle window (Figure 7). This approximately half foot thick line of masonry without scratch coat plaster likely delineates a demolished perpendicular wall of a smaller room. Similarly, just to the right of the middle window, there is a sharp edge on the finish plaster coupled with another approximately half foot wide line of discoloration visible on the finish plaster surface. This area also contains four holes of varying sizes where another perpendicular wall tied into the rear wall to create the other side of a small rear room (Figure 7). Another sharp line in the plaster occurs between the northwest door and the window at the far end. As previously mentioned, the northwest window was likely a passageway to Shenandoah Street, so this divider line may indicate a demolished wall that marked the end of the building rear rooms. Another area on this wall segment that is likely a ghosted element is the approximately 2‐3 foot long, 1 inch wide vertical linear break in the finished plaster surface near the sharp end line of the plaster material (Figure 8). Likely something was previously embedded in this area and has now been lost.

Figure 7. Middle portion of the first floor wall with two ghosts of demolished perpendicular walls indicated.

Figure 8. Sharp line in the plaster between the northwest door and the window that was likely previously a passage to Shenandoah Street. Another ghost on this elevation includes a previously embedded linear element (now gone) that forms a break in the plaster surface.

An additional architectural ghost can be found on the upper northeast end of the wall where a bracket appears to have been embedded in the wall (Figure 9). This may be historic or from shoring efforts to support the wall before restoration.

Figure 9. Architectural ghost, likely from a bracket, found on the upper northeast area of the wall.

Architectural ghosts should be maintained on the wall surfaces during the conservation process because they help the viewer to interpret the changes in the building over time. Special care should be taken during cleaning and repairs to not remove or fill these important elements.

Overall Conditions

Plaster/Stucco

In her report, Gulick notes that any previous conservation treatments made to stabilize the exterior plasters of Building 38 have not been documented, though physical evidence in the form of at least two different campaigns of skim coating or replacement are apparent and a record of a “restoration project” in 1990 exists. These areas of repair campaigns are evident both from comparisons of modern and historic photographs of the wall, as well as through visual and tactile inspection of the wall’s surface.

Large areas of the wall do not have the appearance of a historic plaster finish coat upon close inspection, but instead have the very hard surface and fine aggregate texture of a cementitious skim coat. It should be noted that the addition of these cementitious repairs changes the materials description of this rear wall. While the original wall was covered in plaster – a lime and gypsum‐based building coating material system – the repairs contain cement which moves the material into quasi‐ stucco terminology. The presence of the skim coat is especially apparent at breakages in the surface where a grey layer can be seen on top of the original finish plaster layer (Figure 10). Areas around openings like doors and windows appear to have a thicker buildup or even fill in some areas of the cementitious material; this is also more apparent at breakage areas (Figure 11).

Figure 10. Area of breakage showing the layer of cementitious skim coat (indicated) on top of the finished plaster layer and painted white. Note the difference in texture between the cementitious skim coat below the hole versus that of the smooth, finely layered gypsum finish above.

Figure 11. Areas around openings in the wall display a thicker layer of the cementitious skim coat and sometimes fill tying into the historic plaster. Note the difference in texture and layering in the left image of the southwestern second floor door.

The cementitious skim coat is also thicker and more visually notable in the 2‐3 feet above the surface of the current porch as well as in the northeast corner and northwestern half of the first floor (Figure 8).

The areas above the porch consist of a thicker grey skim with a more tooled appearance and an extremely hard surface can be found here (Figure 12). The areas on the first floor are somewhat smoother in texture, but no less hard‐surfaced. This work was likely done at a different time period than the thinner skim coats found in the upper areas of the wall and likely occurred after the HSR in 1982 where photos show the rear wall without the porch, much more in alignment with what we see in the

1964 HABS drawings (Figure 4). Likely this porch was built and the wall areas above and below it were coated with this material to protect the extant surface during the 1990 restoration by the NPS.

Figure 12. Area 2‐3 feet above the rear porch has a much thicker coat of cementitious material and appears to have tooling marks.

It appears that 90% of the extant plaster on the rear wall of Building 38 has been treated with a skim coat of some sort of cementitious material painted white to resemble gypsum plaster (Figure 13). This undocumented skim coat appears to have been added in a couple of different campaigns, likely in order to help stabilize the plaster as it was disintegrating due to weathering and lack of regular maintenance once this building ceased to be a dwelling.

Large areas of the second floor plasters sounded detached and even sometimes hollow beneath this skim coat upon acoustic sounding (see Appendix II for mapping of these areas). This suggests that removal of this well‐adhered cementitious layer would likely cause massive loss of any plaster beneath.

It is therefore recommended that the extant plaster areas be treated with a plaster consolidant and an adhesive where necessary through injection points in areas where acoustic sounding showed detached or deteriorated plaster beneath the surface coat.

Figure 13. Field notes elevation denoting building materials found on the rear wall. The red hatch indicates areas where the plaster has been covered with a cementitious coating of various thicknesses.

The areas left white on the second and third floors are uncoated plaster, while the white areas on the first floor denote masonry wall with scratch and some finish coat.

In the remaining 10% of the coated wall surface where the original plaster and scratch coat is still uncovered and visible, the material is extremely friable. Areas of visible finish plaster contain multiple layers of white gypsum or limewash coating and often these layers are delaminating from one another

(Figure 14). Though most are white, one layer consists of a light blue, perhaps a limewash with ultramarine pigment,4 that is largely visible in the mottled appearance of the remaining exposed historic plaster areas.

Figure 14. Detail of historic plaster surface showing delamination between gypsum finish coat and multiple later layers of finish. In almost all areas of exposed original plaster, this delamination pattern is present.

Upon acoustic sounding, these areas of exposed plaster often flaked, crumbled, or even moved even with the lightest touch, so it should be handled with extreme care to avoid material loss. Areas of friable original historic plaster should be treated with consolidant to affix delaminating layers of finish coat to the surface as well as prevent the scratch coat from crumbling. As with the areas of skim‐coated plaster, a consolidant should be injected behind the plaster around edges and through injection points where necessary and an adhesive system used to ensure attachment of the material to the wall. In areas where the finish plaster layer has bowed out of plane with the wall and the scratch coat has disintegrated, leaving a gap (Figure 15), after consolidation, a historically compatible plaster fill should be carefully built up behind the fragile areas to attach the finish coat once again to the wall. Though damaged, these areas of finish should be retained if possible since the majority of the historic finished plaster has been covered.

4 Pigment type could be confirmed through later materials testing.

Figure 15. Area of historic plaster at the northeast end of the wall where scratch coat has disintegrated and the finish plaster is bowing and gapping out with no physical support.

In areas where only the scratch coat remains on small portions of the upper wall and larger portions of the first floor wall, the scratch coat is very friable and crumbles when touched. This material is filled with visible lime blebs, small shells, and coarse to fine aggregate (Figure 16). These areas should be treated with a consolidant to re‐adhere the plaster particles together and reduce overall friability. As with the areas of exposed finish coat, great care should be taken in treatment to ensure that the plaster is adhered to the wall surface to avoid loss of this historic fabric.

Figure 16. Detail of the exposed scratch coat extant on the first floor rear wall showing inclusions of lime blebs, shells, and a variety of aggregate sizes.

Roofing and gutter issues above the southwestern doorway on the second floor (Figure 17) must be addressed to preserve extant historic plaster above the northwestern door on the second floor. During heavy rain events a large amount of water appears to course down the wall in this area and is causing plaster loss. A comparison of images taken in 2018 and 2021 (Figure 18) shows that the area of finish loss over less than three years is as much as 5 inches square cumulatively. If the water issue with the roof is not addressed, the plaster will continue to disintegrate, even after a stabilization treatment has been completed.

Figure 17. Roof and gutter above area with increasing plaster loss. Note previous degradation of shingle roofing material below the current roofing system as well as some bird activity in the area.

2018 2021

Figure 18. In 2021 (right), more plaster loss is evident in the area above the northwestern second floor door since the condition assessment in 2018 (left). This is likely due to issues with the roofing and gutter system as water was seen coursing down the side of the building here during a rain event onsite.

Cracking

Horizontal and vertical cracks appear across the surface of the finished plaster and skim‐coated plaster of the rear wall ranging from larger ¼ inch wide cracks in some areas to fine hairline cracks in others. A network of larger cracks through the skim‐coated finish is extant at the northwest end of the second floor to the right of the windows, but otherwise cracking usually appears to occur in conjunction with openings in the wall surface like door frames and windows. A few of these cracked areas around openings display loss of surface material as well (Figure 19). Extant cracks can potentially be used as injection points for plaster consolidant or adhesives but should be finished with an injection of a grout or finish plaster mix where appropriate to ensure water does not enter the wall there. Loose plaster spalls around openings and cracks should be reattached to the wall and any voids around them injected with finish plaster or grout mix. Areas of loss around openings should be filled and rebuilt with a historically compatible plaster fill mix receded ¼ inch from the wall surface to convey that they are repairs.

Figure 19. Area of stucco loss (left) and large crack and potential future fragment loss (right) around northwest door opening on first floor.

Ferrous Elements

Ferrous anchors are embedded at various points throughout the rear wall. These elements range from smaller nails to a large railroad tie (Figure 20). These elements are often causing damage to the surrounding plaster material due to corrosion and subsequent expansion of the metal, but being historic features, they should remain in place. Smaller nails should also be left in place as extraction from the plaster would likely cause more damage to the existing material. It is therefore recommended that the ferrous elements be treated with a rust convertor or corrosion inhibitor and cracks around their entry points filled by injection. Regular reapplication of the coating should be scheduled in routine maintenance for the building to prevent further degradation and damage as the coating will weather away over time.

Figure 20. Ferrous railroad tie embedded in the upper northwest end of the rear wall. Note the cracking around the element, likely caused by expansion of the metal fabric during corrosion.

Biogrowth

Though is appears to be primarily concentrated on the first floor, biological growth affects areas across the entire rear wall. The first floor displays large amount of biogrowth due to the prevalence of water in this area and the lack of exposure to sunlight; the area above the rear porch also displays a pervasiveness of biogrowth likely due to pooling water on the decking. Green and pink algae as well as orange mold can be found on the walls, mostly on the first floor (Figure 21). These areas should be treated with a biocide to remove all growth, as should the brick pavement of the rear yard area to prevent biogrowth areas from spreading as well as prevent visitor accidents due to slippery surfaces. A black mold also appears across the surface, concentrated in the area just above the porch and smaller spores can be found in some areas of the historic finished plaster (Figures 22 and 23). Great care will need to be taken in cleaning the friable finished plaster layers with a biocide to remove these spores.

Figure 21. The first floor northwest corner displays areas of green, black, and pink biological growth as well as orange mold that should be removed with a biocide. Much of this water comes from above, dripping down the wall.

Figure 22. Black and green biogrowth visible in the few feet above the rear porch.

Figure 23. Area of historic finish plaster with small spores of black mold speckled across the layers of coatings.

Paint

One area to the left of the northeast door on the first shows brown paint drips, likely from a door repainting campaign, that should be removed from the surface of the stone using a spot treatment with a paint removal product (Figure 24).

Figure 24. Paint splatter on a stone to the left of the northeast door on the first floor that should be removed.

Wooden Elements

A few areas of the wall contain embedded wooden elements that should be protected from insect infestations with an application of a borate‐based treatment (Figure 25).

Figure 25. Embedded wooden elements such as those found on either side of the central window on the first floor should be protected from insect infestations with borate treatments.

Conclusion and Listed Recommendations for Treatment

As mentioned in the introduction, the treatment rationale for this property stems from the Preservation section of the Secretary of the Interior’s Standards. It is therefore recommended that the extant plaster should be cleaned and stabilized to prevent further deterioration rather than removed and replaced in‐ kind. Any fills for missing plaster around wall openings as well as injection points should be slightly receded from the wall surface to convey that they are repairs. Additional plaster should not be added to the first floor to cover the exposed masonry walls, but the extant scratch coat and remaining finish coat should be consolidated and stabilized in these areas.

General Recommendations for Full Elevation

*See Appendix II for mapping of conditions and treatments

TEST all cleaning and consolidation products and methodology prior to full scale implementation.

General cleaning to remove surface soiling and biogrowth should be performed across all stucco wall surfaces and the brick pavement material. No more than hose‐pressurized water should be used in addition to natural bristle brushes and a biocide (quaternary ammonium compound).

o Extreme care should be taken in cleaning areas where material is extremely friable, especially on exposed historic plaster.

o Extreme care should be taken to not remove any architectural ghosting marks during the cleaning process.

o A pressure washer should NOT be used to clean the historic material.

All unstable extant plaster should be consolidated where found to be friable or where acoustic sounding revealed detachment from the wall. Test potential consolidation products (CaLoSiL

E25, Rhoplex MC‐76, OH100, Paraloid B‐72, Paraloid B‐67) to determine the best solvent to use that will not stain the adjacent surfaces. Consolidate the crumbling/friable plaster with the appropriate products with either a plastic pipette or a needle and syringe to the affected area.

Consolidants and/or acrylic adhesives should be applied around fragment edges or through carefully chosen injection points. Injection holes should be drilled as sparingly as possible while still providing for stabilization and re‐adherence of the plaster. Holes should be filled with a historically compatible plaster mix to surface level to lessen visual impact and prevent water ingress.

All areas of exposed historic plaster show delamination of historic finish layers from the plaster surfaces. After gently cleaning the surface of a soiling or biogrowth, a consolidant or acrylic adhesive should be applied using plastic pipettes or a needle and syringe to reattach delaminating finishes to the wall surface. Potential products should be tested before widespread usage to avoid staining.

In areas where the finish plaster layer has gapped away from the wall surface and the scratch coat has disintegrated behind, plaster dust should be gently dusted out of the gap with natural bristle brushes, all surfaces consolidated, and a historically compatible plaster fill should be carefully built up behind the fragile areas to support and reattach the finish coat to the wall.

Re‐adhere any loose plaster or stucco fragments and reattach and inject around the repair location. Most of the stucco fragments are spalls from corner sections of door frames or windows that have large cracks and are partially or fully detaching. Loose fragments should be removed, and the exposed material should be cleaned with a stiff brush and a consolidant applied. Any plaster exposed by removal of the spall should be consolidated and left to cure overnight. An acrylic adhesive should be used to reattach consolidated plaster or stucco fragments. The fragment should be reinstalled in its original location and supported with temporary padded shoring until the adhesive has cured. The cracks/voids around the plaster fragment should be injected with the finish coat of the plaster mix.

Voids in the plaster/stucco surface that could allow future damage to the material through water, insect, or animal ingress should be filled with an appropriate historically compatible mix after consolidation of the edges around the void. Larger fills in areas of loss around openings should be filled and rebuilt with a historically compatible fill mix receded ¼ inch from the wall surface to convey that they are repairs. Any voids associated with architectural ghosting should

NOT be filled.

Cracks should be injected with either the finish plaster mix or an acrylic or lime‐based grout to prevent further deterioration and potential water ingress.

Mortar analysis should be conducted to determine the material composition of the plaster. Use a historically compatible mix to fill areas behind gapping plaster, holes drilled for injection, and any fills or rebuilds needed for losses around openings.

Insect nests should be removed from the surface of the wall and any residue gently removed from the surface of the plaster with water and a natural bristle brush.

All metallic elements should be left in place, lightly cleaned, and painted with a rust converter

(often tannic acid compounds) or a corrosion inhibitor coating. Routine maintenance should be scheduled to recoat these elements regularly to prevent future damage.

Embedded wooden elements should be treated with a wood preservative with borates to prevent future insect damage.

Mineral silicate paints should be used to paint cementitious skim‐coated areas where the grey cement material is showing. Color match the earliest finish coat to the Munsell Color System and select the finish coat to match this color. Mineral silicate paints should NOT be applied to the surfaces of the uncovered historic plaster.

Specific to First Floor

In lower areas of the wall where material between the stones has deteriorated due to rising damp, the joints should be repointed with an appropriate NHL mortar. The pointing should be recessed at least 1‐2 inches from the surface of the stone to stabilize the area without detracting from the current appearance.

The bricked‐in opening at the northeast end of the wall should be repointed with an appropriate

NHL mortar to stabilize the extant brick. The pointing mortar should be formulated to match extant and tooled to be recessed from the brick surface.

Loose plaster dust should be lightly brushed out of the cracks and crevices of the masonry wall on the first floor with a natural bristle brush before consolidation.

Water from precipitation should be redirected away from the building and the rear courtyard as much as possible to prevent pooling that can cause rising damp and plaster/mortar damage as well as extreme biogrowth.

Specific to Second and Third Floor

Address roof or gutter leak causing water damage to upper area of plaster wall so that water is redirected to downspouts and away from the wall.

In areas where black biogrowth spots have appeared on the historic plaster, take the utmost care to not cause any further loss of the plaster scratch or finish coats. Use light water pressure from a pump sprayer to clean and rinse along with very light agitation with a natural bristle brushes and a biocide (quaternary ammonium compound).

Appendix I:

Field Notes from Conditions Assessment

Appendix I: Field Notes from Conditions Assessment23

Appendix I: Field Notes from Conditions Assessment24

Appendix I: Field Notes from Conditions Assessment25

Appendix II:

Conditions Mapping

Blind Detachment Areas of plaster that appear to have detached from the wall surface. Detected through acous c sounding.

Consolidants and/or acrylic adhesives should be applied around fragment edges or through carefully chosen injec on points.

Injec on holes should be drilled as sparingly as possible while s ll providing for stabiliza on and re-adherence of the plaster. Holes should be fi lled with a historically compa ble plaster mix to surface level to lessen visual impact and prevent water ingress.

Appendix II: Conditions Mapping27

Ferrous Elements Iron elements embedded in the wall.

All metallic elements should be le in place, lightly cleaned, and painted with a rust converter or a corrosion inhibitor coa ng.

Appendix II: Conditions Mapping28

Ferrous Elements Iron elements embedded in the wall.

All metallic elements should be le in place, lightly cleaned, and painted with a rust converter or a corrosion inhibitor coa ng.

Appendix II: Conditions Mapping29

Wood Elements Wooden elements embedded in the wall.

Embedded wooden elements should be treated with a wood preserva ve with borates to prevent future insect damage.

Appendix II: Conditions Mapping30

Wood Elements Wooden elements embedded in the wall.

Embedded wooden elements should be treated with a wood preserva ve with borates to prevent future insect damage.

Appendix II: Conditions Mapping31

Insect Nests Insect nests found on the wall surface.

Insect nests should be removed from the surface of the wall and any residue gently removed from the surface of the plaster with water and a natural bristle brush without removing historic fi nishes.

Appendix II: Conditions Mapping32

Insect Nests Insect nests found on the wall surface.

Insect nests should be removed from the surface of the wall and any residue gently removed from the surface of the plaster with water and a natural bristle brush without removing historic fi nishes.

Appendix II: Conditions Mapping33

Gapping Finish plaster layer has bowed out of plane with the wall and the scratch coat has disintegrated, leaving a gap.

Plaster dust should be gently dusted out of the gap with natural bristle brushes, all surfaces consolidated, and a historically compa ble plaster fi ll should be carefully built up behind the fragile areas to support and rea ach the fi nish coat to the wall.

Appendix II: Conditions Mapping34

Biogrowth Biological growth in the form of algaes and molds on the surface of the wall.

No more than hose-pressurized water should be used in addi on to natural bristle brushes and a biocide (quaternary ammonium compound). Extreme care should be taken in cleaning areas where material is extremely friable, especially on exposed historic plas-ter. Do not remove any architectural ghos ng marks during the cleaning process.

Appendix II: Conditions Mapping35

Biogrowth Biological growth in the form of algaes and molds on the surface of the wall.

No more than hose-pressurized water should be used in addi on to natural bristle brushes and a biocide. Extreme care should be taken in cleaning areas where material is extremely friable, especially on exposed historic plaster. Do not remove any architectural ghos ng marks during the cleaning process.

Appendix II: Conditions Mapping36

Cracks found in the surface of the plaster.

Cracks should be injected with either the fi nish plaster mix or an acrylic or lime-based grout to prevent further deteriora on and poten al water ingress.

Appendix II: Conditions Mapping37

Cracks should be injected with either the fi nish plaster mix or an acrylic or lime-based grout to prevent further deteriora on and

Appendix II: Conditions Mapping38

Cracks should be injected with either the fi nish plaster mix or an acrylic or lime-based grout to prevent further deteriora on and

Appendix II: Conditions Mapping39

Architectural Ghos ng Traces of past building elements that are no longer extant.

Extreme care should be taken to not remove any architectural ghos ng marks during the cleaning process. Any voids associated with architectural ghos ng should NOT be fi lled.

Appendix II: Conditions Mapping40

Architectural Ghos ng Traces of past building elements that are no longer extant.

Extreme care should be taken to not remove any architectural ghos ng marks during the cleaning process. Any voids associated with architectural ghos ng should NOT be fi lled.

Appendix II: Conditions Mapping41

Mortar Loss Mortar between masonry units has deteriorated.

Repoint joints with voids with appropriate mortar. Rake and clean joints back to stable mortar. For stone masonry, poin ng should be recessed at least 1-2 inches from the surface of the stone; for brick masonry, poin ng should be slightly recessed from the brick surface.

Appendix II: Conditions Mapping42

Mortar Loss Mortar between masonry units has deteriorated.

Repoint joints with voids with appropriate mortar. Rake and clean joints back to stable mortar. For stone masonry, poin ng should be recessed at least 1-2 inches from the surface of the stone; for brick masonry, poin ng should be slightly recessed from the brick surface.

Appendix II: Conditions Mapping43

Paint Loss Areas of the cemen ous skim-coat areas where the coa ng has weathered and gray surface is visible.

Mineral silicate paints should be used to coat exposed grey cement material. Color match the earliest fi nish coat to the Munsell Color System and select the fi nish coat to match this color. Mineral silicate paints should NOT be applied to the surfaces of the uncovered historic plaster.

Appendix II: Conditions Mapping44

Paint Loss Areas of the cemen ous skim-coat areas where the coa ng has weathered and gray surface is visible.

Mineral silicate paints should be used to coat exposed grey cement material. Color match the earliest fi nish coat to the Munsell Color System and select the fi nish coat to match this color. Mineral silicate paints should NOT be applied to the surfaces of the uncovered historic plaster.

Appendix II: Conditions Mapping45