Bandelier Historic Structure Report: CCC Buildings

BUILDING COMPONENTS (continued)

Walls

The structural integrity of the masonry walls appears to be sound overall. Isolated areas of apparent settlement exist, most notably in B-2, B-19, and B-27D. The cracking at the end of B-2's portal (figure 172) is more a result of water leakage from above and movement of the lintel than of actual settlement. [3] This leakage is further evidenced by the latia staining and the amount and nature of water-induced surface efflorescence present (figure 173). Isolated areas of similar but lesser efflorescence exist on other buildings. Because of the geological phenomena that deposited much of the area's volcanic tuff, significant amounts of gas were entrapped, making the stone a highly absorbent material. Because of this porosity, efflorescence may be expected to flush out over time. The crack on the exterior face of the portal (figure 174) appears stable. The former crack in B-27D (figure 175) was replastered in 1986 and there has been no apparent movement since. Other areas of settlement existed within the parapets as a result of deteriorated column bases. Through borescopic reading in 1985, voids as deep as 24 inches were found to exist under the floor in B-19. [3] These voids were the apparent result of past leakage of subfloor water pipes, threatened the integrity of the stone flooring and adjacent masonry walls. Floor and wall cracking indicated settlement of as much as 2 inches in the interior wall. Recent filling in of these voids has corrected this condition.

Figure 172. Wall crack in B-2 portal parapet. (Photo: Copeland for NPS)	Figure 173. Surface efflorescence from falling damp on B-2 portal parapet. Note similar condition of rising damp on adjacent wall. (Photo: Copeland for NPS)

Figure 174. A wall crack on the B-2 portal parapet. (Photo: Copeland for NPS)	Figure 175. A plaster crack in B-27D before replastering. (Photo: Copeland for NPS)

Along much of the north wall of the cabin complex that faces the cliff's runoff, the masonry becomes saturated during heavy rainfall. Given the type of stone and the severity of this runoff, the walls are in surprisingly good condition. This condition can be controlled as outlined elsewhere.

Mortar used within the stonework reportedly consisted of three different mixes: one for the foundations, one for the walls, and another for the parapets and their capping. Visual remains bear out the report and reveal that the buildings' pointing is the struck setting mortar. The majority are cement-based mixes, which, according to the original specifications, ranged from 1:3 to 1:5 (cement: sand) with 10 percent lime added. This mix is appropriate to the stone's approximate compressive strength of 850 pounds per square inch. A clay-based mortar was used to a lesser extent, primarily within the wall planes. Recent sampling and analysis for mortars and stuccos further support this range of constituent compositions. The results of this sampling from 14 buildings will be included in the historic structures preservation guide and data collection for the buildings. One noted characteristic of the mortar is its slight variation among buildings and even within a single structure. Repointing efforts over the years have been relatively compatible in color and texture but often have a smoother, more smeared tooling than the original. Their overall range and variety have perpetuated the buildings' subtle variations. Recent repointing efforts have often been too uniform and, in general, are incompatible with the original mortar in color, texture, and tooling and adversely affect the overall visual character (figure 176).

Figure 176. Detail of B-10 showing recent repointing efforts. Note the cap installed on the attic vent. (Photo: Copeland for NPS)

Today, a significant amount of mortar has lost its bond with the adjacent stone plane, allowing moisture to intrude. This condition is particularly noted on the parapets, under canales, and adjacent to wood members. The cement-based parging (stucco) at window jambs and above lintels is in generally poor condition (figures 177-179). Much of the parapet coping parging is loose; the majority of these areas have been surface coated with the roof membrane but not at the exterior face. The cap on these parapets originally sloped to the building roof. Subsequent repairs have changed much of this area so that it now directs runoff onto the wall plane, thus increasing the potential for absorption. Maintaining the integrity of the mortar joints and parging is vital to the preservation of the buildings, as is maintaining the design integrity of the parapet caps. Particularly on the entrance road wall (B-31), many stones are loose or missing (figures 180 and 181). Although that wall is not part of this study, it deserves the same maintenance attention and sensitivity as the remainder of the buildings.

Figure 177. Detail of typical parging separation at a window jamb. (Photo: Copeland for NPS)	Figure 178. Detail of typical parging separation at a lintel. (Photo: Copeland for NPS)

Figure 179. Detail of typical parging separation at a lintel. Note the mortar separation at the masonry overhead. (Photo: Copeland for NPS)

Figure 180. Detail of the entrance road wall (B-31), showing loose, separated stone. (Photo: Copeland for NPS)

Figure 181. Detail of the entrance road wall (B-31), showing missing stones. (Photo: Copeland for NPS)

Much of the original mud stucco (or sympathetic reproductions of it) remains (figure 182). The trend toward using a stronger, cement-based, painted plaster under portals, which began in the 1940s for maintenance concerns, continues. This new material gives the walls a much harder, cleaner appearance than the original mud mix. Many of these painted wall bases under portals have a much higher painted plane than earlier schemes and today have a scalloped edge design. Although an exterior rendering may provide protection and a certain amount of sealing to the stonework, it should be remembered that the original coarse stucco was applied to provide a visual softening and artificial aging to the structures aesthetic. Restucco efforts should retain this design intent rather than be a mere stucco wash that totally changes the essential character of the stonework (figures 183 and 184).

Figure 182. Detail of the original mud stucco, B-6. (Photo: Copeland for NPS)

Figure 183. The rear of B-9, showing the original character of the partially stuccoed masonry. (Photo: Copeland for NPS)

Figure 184. The rear of B-2, showing the change in masonry character as a result of recent restucco efforts. (Photo: Copeland for NPS)

At some point, B-26 was given a Hypalon coating over its exterior walls. This material, contrary to its intended purpose, trapped embedded moisture and increased surface spalling. Under the Package 224 work, the Hypalon was peeled away and a stucco coating installed.