Bandelier Historic Structure Report: CCC Buildings

BUILDING COMPONENTS

Because of the timing of this report's completion (in relation to actual rehabilitation work), existing conditions are discussed in terms of both general conditions before Package 224 rehabilitation projects and conditions found today. Actual package-funded construction commenced in fiscal year 1982 with the first of several contracted utility projects and continues periodically on miscellaneous wood repairs through Southwest Region Cultural Resource Center day labor. In addition to congressionally allocated funding, approximately $75,000 was raised through private donations to the National Parks and Conservation Association. These park, region, and DSC projects included the following:

Rehabilitate Water, Sewer, and Electrical Services (drawing 315/41,008A)

Install Insulated Windows (drawing 315/80,026)

Renovate Electrical and Gas System (drawing 315/41,009)

Renovate Water System (drawing no. 315/41,010)

Install Insulated Windows (drawing 315/41,012)

Replace Canales and Miscellaneous Roof Repairs (drawing 315/80,030)

Rehabilitate Vigas, Columns, and Miscellaneous Wood Members

Replace Flagstone and Curbstone

Install Fire and Intrusion Alarm System

Components of this report have been previously submitted and approved for much of the work undertaken to date.

Because of continued occupancy and maintenance, the buildings are in generally sound condition. The buildings retain much of their original fabric and most of their original design integrity. However, certain deficiencies of material or design or both require treatment to ensure the buildings' continued preservation and historic character. Because the buildings are similar in design, construction materials, and condition, existing conditions are discussed by building component rather than by individual building.

Roofs

Except for B-30 and B-25, all the original structures retain their original shed roofs drained through canales; later additions have retained shed roof designs. B-30's original mineral roll roofing has been replaced with asphalt shingles; B-25's canales have been removed along the south elevation and a metal gutter has been installed. The infill roof connecting B-15 and B-16 (over the former terrace) has a shed roof draining into two internal drain lines. B-1's rear parapet has been removed and metal drip flashing has been installed (figure 154).

Figure 154. Rear (south) elevation of B-1, showing removed parapets and roof gutter modification. (Photo: Copeland for NPS)

All the original composition roofs had been previously replaced, some as early as 1946 and others as late as 1962. Except for B-30, all roofs were replaced again in 1980. This work consisted of removing the existing roofing and exposed metal flashing, installing 4 inches of sprayed polyurethane foam insulation, and using a class A, 30-mil, spray-applied Gacoflex U-66 series urethane coating over the roof and parapets.

This system initially had extensive pinhole leaks and surface blistering. Many of these leaks apparently resulted from deficient mixing of the various mix components and resulting gassing-over of microvoids at the foam surface; these pockets eventually broke, causing a loss of substrate for the urethane. This loss of bond in turn produced holes in the system and points of leakage. As in most roof systems, the blisters had resulted from inadequate bonding and entrapped air. These conditions were supposedly corrected under manufacturer warranty in 1987, but leaks are still present.

Today, other than these continuing leaks, the primary area of concern with these roofs is the condition of the underlying sheathing and the parapet seal (see "Walls"). In at least one known instance, B-21, severely rotten sheathing and wood deterioration in the skylight framing were not replaced before the roof was installed. Similar, but less serious, conditions have been encountered during recent wood and roof repairs. Additional areas are suspected to have deteriorated but are difficult to assess or verify in a nondestructive manner.

Other conservation concerns with this roofing system or its application or both are as follows (figures 155-157):

It raised some roof levels to a point flush with the bottom of vigas at intermediate roof parapets, resulting in increased water exposure and a denial of the drying effect of air movement.

Extensive colonies of ants have been uncovered living in the foam.

It provided a questionable terminal seal at the parapet copings.

The material encapsulated utility lines running across the roofs or parapets, making their future repair or removal more difficult and costly.

It lessened the throat opening at canales and scuppers.

It closed off some roof vents and changed the configuration of the parapet coping so that water drains onto exterior wall surfaces rather than onto roofs.

Figure 155. B-15/16 roof, showing spray membrane on parapets, 1984. Note several park efforts at sealing leaks. (Photo: Thorson for NPS)

Figure 156. Blistering of roof membrane, B-13/14 portal, 1984. (Photo: Thorson for NPS)

Figure 157. Roof over B-2 rear portal, 1985. Note embedded utilities, spray membrane on parapets, and fallen limbs. (Photo: Copeland for NPS)

The roof surface throughout the building complex is a strong visual component from the approach drive. This new roof membrane was often applied as an attempted parapet seal as well. Its extension over the parapet coping is highly visual from below, unlike a traditional, flashed, built-up roof. Added to this visual incompatibility and the other problems cited is a major concern with the material's long-term performance. This coating is easily punctured by foot traffic or fallen tree limbs. In addition to allowing leakage, this puncturing exposes the underlying foam to degrading ultraviolet light and apparent insect intrusion.

By contrast with the above system, roof repair work executed to date under this package has used a 15-year, warranted, 45-mil, ethylene propylene (EPDM) roofing membrane, manufactured by Carlisle, with copper counterflashing. This repair has occurred on B-13, B-21, and B-26, B-7 and B-11's woodsheds, B-23's porches, and the B-29 portal, and for flashing at all replacement canales (figures 158 and 159). A gravel-ballasted system has been used to provide the required ballast and also to restore the buildings' graveled roof appearance. One dilemma in the further use of this system is the required ballast weight. A traditional composition roof weighs approximately 4 pounds per square foot; fully ballasted membranes require 10 pounds. Loading capacity is easily calculated for those buildings on which the exposed (from below) viga is also the roof rafter. On the remaining buildings where a secondary rafter system of 2x's exists (figure 160), this calculation requires no destructive investigation. Of this latter system, only B-27's actual framing system has been viewed. In this case, the secondary rafters were of varying lengths scabbed together. Because of the budgetary limitations on the buildings' original construction, it is suspected that this scabbing may well be a common occurrence. Because of a limited loading capacity in these situations, a fully ballasted membrane is a suspect alternative for future roof work without extensive rafter reinforcement or replacement; however, other methods of EPDM roof attachment exist that do not pose major concerns for structural capacity.

Figure 158. Roof replacement underway at B-29 portal, 1986. Note original roof vent covered up by membrane application to parapet. (Photo: Hose for NPS)

Figure 159. New ballasted roof on B-21, 1985. (Photo: Copeland for NPS)

Figure 160. Typical original parapet and roof framing detail with secondary roof framing.