CABRILLO Historic Structures Report

REPAIR PROCEDURES (continued)

Wood elements

Description

Wood is not used extensively at Cabrillo National Monument, although it is found on some structures. Various applications include the following:

• Wood-framed roof. Examples: Army Radio Station.

• Wood doors. Examples: Army Radio Station.,

• Metal-clad wood doors and frames. (See Ferrous Metal Section)

• Wood windows. Examples: Generator Station for Searchlight No. 18 and No. 19, Army Radio Station.

• Wood curb at searchlight shelter roofs. Examples: Searchlight Shelters No. 15 & No. 18

• Wood furniture. Cabinets, shelves, and benches constructed for use in structures. Examples: Searchlight Shelter No. 15 and No. 19, Base-End Station Calef & Wilkeson, and Base-End Station Woodward & Grant, and bunk beds at Battery Point Loma Bunker Complex.

• Trim. Wood trim used around doors, windows, etc. Examples: Army Radio Station.

Figure 39. Deteriorated wood curb at Searchlight Shelter No. 15.

Conditions

Weathered Wood, Dry Rot, and Splitting

Wood is vulnerable to biological decay from exposure to moisture. Rapid cycles of wet and dry conditions in poorly protected wood causes cracking and checking that will lead to further decay. Searchlight Shelters No. 15 and No. 19 exhibit this condition at the wooden curbs surrounding the metal roofs. The unpainted curbs are exposed to salt spray and ocean winds, resulting in checking and dry rot as well as detachment.

Missing Elements

Missing wood elements are typically small trim pieces. Although these losses are non-structural, they are an architectural concern. Wood may become detached because deterioration or checking has weakened mechanical fastenings, or through theft or vandalism. Wood elements are easy to detach and if not reattached immediately will be lost.

Missing Paint

Unprotected wood can decay if left exposed. Blistering and peeling paint are the first signs that the structure is in need of maintenance. See Paint section, below, for more information.

Insect Damage

Although no insect damage was observed during the survey leading to this report, insect inspections should be a regular feature of periodic maintenance. These inspections would identify any ongoing attacks before they became serious. Insects causing damage to wood include beetles, ants, bees, wasps, and termites. It is important to identify the attacking insect. Relevant information includes type of wood attacked, the age of the wood, the type of damage, and the consistency of the boring dust.

Recommendations

Research original documents to determine whether wood elements were originally painted. Conduct a paint study to determine color schemes. Since the concrete structures appear to have been originally painted, it is likely that wood elements were likewise painted.

General Wood Repair Methodology:

1. Survey the existing condition of all wood elements.

2. Sample woods and send to a laboratory for identification. (The U.C. Forest Products Laboratory in Richmond, California, performs this service. )

3. Remove all dirt, debris and miscellaneous attachments.

4. Remove any finishes if loose, blistering or peeling.

5. Treat wood elements selectively with fungicide and brush-on consolidant as required.

6. Replace-in-kind or consolidate deteriorated wood elements as required.

7. Treat with wood preservative and finish to match adjacent material.

Wood Windows

In addition to items 1-6 under General Wood Repair Methodology, above, perform the following:

1. Restore window to proper operation.

2. Install new hardware, where missing, to match original.

3. Install new glazing where cracked or missing.

4. Replace glazing compound.

5. Prepare wood surfaces, prime, and paint.

Wood Doors

In addition to items 1-6 under General Wood Repair Methodology, above, perform the following:

1. Repair splits and separations with waterproof glue as required.

2. Finish to match adjacent, if any, or finish to match original.

3. Recondition hardware, and install new hardware, where missing, to match original.

Recommended Tests

1. Wood identification.
2. Paint analysis (see Paint, below).

Wood References:

Myers, John H. Preservation Briefs No. 9: The Repair of Historic Wooden Windows. Washington D.C.: Preservation Assistance Division, National Park Service, U.S. Department of the Interior, 1981.

Look, David W. Preservation Briefs No. 10: Paint Removal from Historic Woodwork. Washington D.C.: Technical Preservation Services, U.S. Department of the Interior. 1982.

Ashurst, John, and Nicola Ashurst with Geoff Wallis and Dennis Toner. Practical Building Conservation: English Heritage Technical Handbook; Volume 5 Wood, Glass & Resins. Aldershot, Hants: Gower Technical Press, 1988.