Oregon Caves Historic Structures Report

PART IV
Exterior Assessment and Recommendations

Roofing and Flashing

The roof of the Chateau is formed by a series of intersecting shapes. The main gable, running north-south across the center portion of the building, intersects two main cross gables over the north and south wings. Two large gabled dormers project from the northern and southern sides of these wings, facing out to the surrounding hillsides. Two small gable dormers were cut into the main gable at the time of the sprinkler system installation in 1950. The third floor guest rooms are covered by the two gables of the north and south wings, and shed dormers that protrude from the east and west sides of the main north-south gable.

Roof, general field on the east side.

This complex series of roof shapes and intersecting forms is unified by the treatment of the roof. It is covered with wood shakes, 1/2" thick and 24" long. The exposure varies from 9 to 10 inches, but is consistently within this range. There are two layers of shakes on the roof, both split and re-sawn. It is evident that a second roof was applied over the original shake roof, keeping the same exposure and character of the original. This second roof was applied sometime after 1950, when the two small dormers were added in the attic on the east and west sides of the building.

The roof is supported by full dimension 2" x 6" rafters, 24" on center. The roof peak is created by the intersection of the rafters, and there is no ridge member. Eight inch lap sheathing is used as the substrate for the roof, and is not fit tightly together. There are small gaps between each piece, typically less than 1/8". The 3/4" thick sheathing is laid horizontally, and is covered by building paper beneath the bottom layer of shakes.

Fascia board for gutter.

The top layer of shakes is beginning to deteriorate. While the attic has remained dry, the shake roof has steadily deteriorated. There are many missing and broken shakes, and most are curling. The exposure is larger than the recommended length of 7-1/2" as described in Architectural Graphic Standards, but the shakes have weathered fairly well. The formula for exposure is given as (Length-2") / 3, which results in the equation of (24-2) / 3 or 22 / 3 = 7.33. This is rounded up to the 7-1/2" dimension given on page 76. A ten inch exposure is typically reserved for vertical surfaces, according to Graphic Standards. The ridge shakes, also experiencing areas of missing and broken pieces, are cut to fit tightly around the projecting rooftop sprinkler system.

The Chateau does not have a gutter system; instead the water is allowed to run off the roof at the edges. The rafter tails are exposed, as is the sheathing beneath the eaves. The only area that the rafter tails are covered is above the main entrance to the hotel lobby on the south side of the building. A 2" x 6" board has been nailed to the rafter tails to serve as a backer for a gutter that is not in place during the winter. This board is allowed to project slightly out from the edge of the eave, and as a result all of the runoff above the board flows over it. The board is saturated in periods of heavy rain and snow melt, and the moisture is wicking into the ends of the rafter tails above the door. The sheathing in this area is also wet as the water travels through the rafters and fascia board.

The wide overhangs of the Chateau have created problems in one area. On the west side of the structure, in the southern valley that runs between the intersection of the south wing cross gable and the main gable, the sheathing is broken. This is most likely due to snow loading, since the area is protected from sunlight during the winter months as it faces north.

Another problem of the overhangs is that the rain is not allowed to reach all areas of the roof and wash them free of debris. Moss and lichens have begun to grow on the roof in areas that are protected from the weather, especially under the shed roof sections on the north and west sides. The growth is uphill of the drip line of the eave above. The shed roofs that project over the lower entrances to the building are suffering the same growth problems. The entrance to the coffee shop and dining room from the pond area are experiencing heavy growth, as are the roof structures over the stairs to the boiler room and outside entrance to the kitchen.

Sheathing damage.

Growth uphill of drip line.

Small dormer, west side. Note the damage.

The roof valleys are flashed with galvanized sheet metal that was historically painted with a red lead paint to protect the metal. The valleys are all open, and the flashing has been crimped to prevent runoff from one roof plane from running under the shakes on the opposing roof plane and infiltrating the wood structure. These valleys are losing their paint as years of runoff have eroded the paint surface. In some locations the zinc galvanized coating is also eroding, and the valley flashing is beginning to rust.

An access panel, located in the attic just east of the chimney, provides a close look at the chimney area and roof. From this vantage point the problems with the shakes are readily visible.

Rooftop sprinkler, main ridge.

Just south of the hatch and chimney is a large area of sheet metal roofing that is woven under the step flashing of the chimney. The sheet metal was originally galvanized, but over the years the zinc galvanizing has worn off, leaving exposed steel sheet metal. The hatch itself has galvanized step flashing woven in with the shakes, which is coated with red lead paint. The hatch cover is removed by lifting it off of a projecting frame, allowing inspection of the hatch. The hatch is clad with sheet metal, lapped and painted with a red lead paint. The original design provided for the hatch to be held in place by its own weight, which proved to be insufficient. The hatch has blown off of the projecting frame from time to time, and as a remedy it has been connected to the building temporarily with a piece of 12-gauge wire wrapped around the rooftop sprinkler system pipe.

Recommendations for Treatment: Roof

The treatment of the Chateau roof can be broken down into seven different components. These are both short and long term solutions, and are also basic maintenance. The recommendations for roof treatment are:

• Keep the roof valleys clear of excessive snow loads. One valley has already received sheathing damage due to overloading, and the historic fabric has been compromised. The damaged area should be repaired before the next winter to avoid further damage.

• The fascia board for gutter support should either be removed or the gutter permanently installed. The concessionaire has undergone a Section 106 review for the addition of a gutter above the main lobby entrance, and is allowed to place a gutter at this location.

• The roof hatch near the chimney should receive a more permanent locking mechanism. Providing a set of stout latches and hinges would protect the door from being blown off of the building, and would reduce the risk of the hatch being dropped inside the attic after removal and falling through the historic fabric of the ceiling.

• The growth on the roof should be kept to a minimum. A moss killer should be applied to the roof to reduce the growth, protecting the shakes from accelerated decay. Care should be taken when applying the chemical so that excess does not fall to the ground and damage vegetation around the eave line of the building.

• The sheet metal roofing between the chimney and the ridge should receive a new layer of paint to protect the metal. The material, galvanized steel, is still sound, but neglect could result in further decay of this system, allowing water to infiltrate the attic space. The joints between the sheets should be inspected to make sure they are weathertight before the area is painted. If repair is necessary, the work should be done prior to painting.

• The galvanized metal in the valleys should be repainted before the galvanizing is compromised. This needs to be done with care to avoid excessive amounts of paint on the shakes. The valleys should be cleared of debris and inspected for damage prior to painting.

• Within five years, the roof will need to be replaced. The number of broken and missing shakes increases every year, and while the attic is dry at this point the chance of water infiltration into the building envelope increases every year. The historic exposure, texture, and thickness should be maintained, and the ridge detail should be kept the same. A copper or galvanized ridge flashing may be installed to curtail moss and lichen growth on the roof, but will not help in areas that are under the eaves. The fungicide should be used to control the growth on the roof. Replacing the roof would be an ideal time for other work outlined above, including valley flashing inspection, repair, and painting, flashing the fascia board above the lobby entrance, and repair of the sheet metal above the chimney. This work should be completed before the roof begins to leak, compromising the building envelope. The roof should be replaced in-kind, with resawn shakes.

Keeping the snow load from becoming excessive and the use of a fungicide are maintenance operations that should be performed on a regular basis. The roof replacement, while costly, will help protect the building and preserve the integrity of the structure and interior finishes.

orca/hsr/hsr4.htm
Last Updated: 22-Sep-2001