V.2.1
Trailside Shelters
General Conditions


This section of the report consists of the condition assessment and evaluation of the Trailside Shelters. Assessment addresses physical conditions of the shelters based on field observations conducted by the NPS staff and consultants over the past several years. Evaluation is a discussion of treatment options and recommendations.

Conservation Goals

The basis of judgment for evaluating the shelters is a Conservation policy of preserving the historic shelters for the continued dual-purpose of emergency and inclement weather use by both recreational users and park maintenance staff. An important aspect of such a policy is to understand that cultural management of the shelters includes both the individual structures and the shelter system as a whole. The underlying principal of this policy is the desire to preserve both the original design and materials of these historic structures in their landscape setting and the relationship of the shelters within the trail system, all the while addressing life safety issues within a long-term maintenance program. Such preservation measures may include limited restoration of deteriorated material and replacement in-kind of material and assemblies that have reach their service life. In addition, there is a discussion on some restricted structural intervention for certain shelters in heavy snow locations. The goal of these measures and policy is to comply with the provisions of the Olympic National Park General Management Plan (approved August 8, 2008 - See Appendix 1) and be in accordance with the Secretary of the Interiors Standards for the Treatment of Historic Properties.


Elements of Significance and Character Defining Features:

Within the goal of preserving the shelters, the concept of significance plays a vital role in establishing maintenance policy. For historic structures, significant elements are those qualities of the building that provide historic meaning and understanding.

There are two areas of significance that need to be recognized and addressed in preserving the trailside shelter. The first concerns the siting of the shelter and its historic relationship with the landscape. The second concerns the actual structure itself.

For the earlier period trail shelters constructed by the Forest Service, significant site features may be the orientation of the shelter to prevailing storm patterns, its location on the landscape in terms of providing space for stock, its relationship to water sources, and the surrounding vegetation. These early shelters were practical structures for working staff. In addition to removal of vegetation immediately around the shelter for structural preservation (discussed later in this section), the larger landscape aspects around the shelter should be reviewed as part of a preservation planning process in terms of more extensive vegetation removal, connection to natural meadows, and views of clearings. Historically, the areas around the shelters would have been kept clear from stock movement and the gathering of fire wood.

For the later shelters built by the National Park Service that were more orientated towards recreational users, elements of significance landscape siting would include view sheds and vegetation management to enhance or frame such a view. Maintaining historic view sheds could involve removal of selected areas of undergrowth or complete removal of trees. 1

Vegetation removal immediately around the shelters is crucial to preserving the base logs of the shelters. Removal of second growth trees in the immediate vicinity of the shelters may be necessary to increase air circulation and decrease the potential for storm blow-down damage.


In terms of significant character defining elements of the shelter structures, these are embodied in the rustic form of the original log/beam design and construction, the use of often oversize structural members with their expression of strength and scale, the universal feature of the offset roof slopes with the distinguishing "roof combing", and the use of wood shakes for the sheathing and roof. Replacement in kind is critical in retaining the historic qualities of the shelters. Where the wood shakes were replaced on some shelters with board and batten, this pattern may be considered a feature that has gained significance over time and should either be retained or returned to the original wood shakes. Improvements recommended for increased snow load capacity (as presented later in the section) need to designed and constructed of similar material to the existing frames and blend in a form.

Last, the shelters ca not be removed from the context as being part of a trail system. The concept of connectedness of shelters along a trail at a series of regular interval is an important character in regards to the early Forest Service shelters. There was thought and purpose to their placement and at least in one location within the Park an historic series of shelters should be preserved.


General Observations:

There are several universal conditions noted for nearly all the shelters. These will be addressed here under a general discussion with the understanding that they apply to all the shelters in some degree. Later, in the discussion of individual shelters of the various developmental periods, such conditions will be reference to this section.

  • Site Conditions:

    Assessment

    It was observed in most instances that the site grade around the shelters has grown over time with forest duff and debris. This accumulation of material has raised the grade around the bases of the shelters such that in many instances the lower portion of the sill logs actually sit below grade. Many shelter frame assemblies are suffering sill log deterioration from this condition. This build up of material has often reshaped the surface drainage around the structures, causing water to course into and at the base of the shelters. Drainage is also affected by the domed fire hearths found in front of many shelters and the often seen depressions inside the shelters. Around the shelters, one often finds a substantial growth of brush and shrubs. This growth both feeds off the moisture and retains this surface moisture close to the base of the building.

    Evaluation.

    The shelter structures are designed for the sill logs of the frame to bear on pier stones set in the ground. The stones were placed to raise the sill logs at least three (3) inches above the surrounding grade. The grade around the base of the shelters should be removed to expose the stone piers and allow free air movement under the sill logs. Where sill logs are just beginning to deteriorate (say with only one (1) inches or less deterioration on the surface), this measure should allow the log to dry and reduce the rate of deterioration, and in some instances allow retention of the log instead of replacement.

    In lowering and regrading around the base of the shelters, it is critical that contours be established to collect and move surface moisture down and away from the shelters. Most likely, this will require formation of surface swales. These swales do not necessarily need to be ditches, but rather broad, shallow surface contours with a positive drainage to the downslope of the site. In some instances, the elevation of outside fire hearths will need to be altered and interior depressions filled in.

    Where vegetation has grown around and against the shelters, this vegetation both holds moisture close to the shelter and prevents airflow for drying.

    Recommendation:

    1. Regrade site at each shelter for positive surface moisture drainage.
    2. Lower site grade to a minimum of three (3) inches below bottom of sill logs. (an option would be to raise the pier stones when replacing a sill log, thereby raising the shelter to account for duff build-up)
    3. Remove all vegetation around the shelter a minimum of five (5) to seven (7) feet from shelter walls.

    Structure

    Assessment

    One of the great natural phenomena of the Olympic Peninsula is the extraordinary variation in precipitation. The following map reflects locations with less than 20 inches of precipitation per year to over 270 inches per year.




Shelter Development General

Figure No. 1: Annual Precipitation map for Olympic National Park. Shelters at the higher elevations can experience significant snow accumulations.

  • Historically, trail shelters have often been lost to heavy snows. Some of this is due to age and fatigue, but some is also due to the character and design of the typical older style trail shelter structure from Period I.


Shelter Development General

Figure No. 2: The Standard Plan L-4 of the Forest Service shelter from 1934 Recreational Handbook.


  • The older style trail shelters are based on the standard plan L-4 as seen in Figure No. 2 above. Shelters of this style at Olympic National Park are constructed either of Cedar or Douglas Fir. Depending on the type of material, the ability to withstand snow loads varies.

    If the L-4 shelter is constructed of Douglas Fir as shown above, and the lowest structural values for DF are used in an analysis (poor logs are used), and loaded with a very dense snow, it can support only about 9 inches of snow before the back center beam is over stressed. If the beam is braced with either knee braces or a central pole, then the structure can support four (4) feet of snow. In the case where snow exceeds four feet, all cross beams would need additional support, and the structure would be limited to a maximum of seven (7) feet of snow due to the size of the rafters.

    If the L-4 shelter is constructed of Cedar as shown above, and the lowest structural values for Cedar are used in an analysis, and loaded with a very dense snow, it can support only about 1 inch of snow before the back center beam becomes over stressed. If the beam is braced with either knee braces or a central pole, then the structure can support four (2) feet of snow. In the case where snow exceeds two feet, all cross beams would need additional support, and the structure would be limited to a maximum of four (4) feet of snow due to the size of the rafters.

    Evaluation

    Based on the precipitation map, there are places in the Park where shelters receive snowfall in excess of the structural limits of the structures as analyzed. Shelters sometimes survive because the snow is less dense and the actual logs used were of superior grade. In other cases, the insertion of bunks in the shelters involved additional vertical supports, which in turn actually increases the capacity of the frame. But under severe snow conditions, the standard shelter structure, without bunk frames, is susceptible to failure.

  • In those shelters where bunks exist, maintaining the bunk frame uprights under the beams of the frames will be especially beneficial for long-term preservation.

    For those shelters located in areas of average heavy fall, temporary shoring could greatly enhance the survival rate of these historic shelters. Installed in the fall and removed in the spring, such temporary shoring though would be an added annual maintenance item, placing further strain on an already burdened staff. In these instances, consideration should be given to rehabilitating the shelters with historic bunk designs. Where the bunks are missing, they should be restored with a support column under a cross beam. Where present, modify existing design by adding additional vertical supports to overhead beams.

    In both instances, depending on snow depth of location, permanent additional supports will be needed at the front beam.

    Recognizing such conservation measures affect the historic character of these select shelters (ones in heavy snow locations), they enhance the long-term survival of the historic structure with minimal intervention. Properly documented, these measures are a reasonable treatment for the historic shelters.

    Recommendation

    1. As part of annual shelter maintenance for those shelters found in areas of heavy snow accumulations, and which have bunks frames, inspect all interior column supports, Insure they are sound and firmly in place. Repair or replace any deteriorated members.
    2. For those shelters in heavy snow locations without bunk frames, install new frames and bunks for additional support.
    3. For all shelters in heavy snow locations, install additional supports under the front beam.

  • Roofing:

    Assessment

    The roof of the shelters is universally of cedar shake. In areas of dense timber the roof will accumulate needle duff, twigs, and cones over the course of a year. This material then encourages moss growth. The layer of debris and moss will have a tendency to retain and hold moisture.

    Evaluation

    While recognizing the exceedingly wet climate on the western slopes of the Park, the yearly buildup of this material accelerates the deterioration of the roof shakes. Though rate and degree of accelerated deterioration is difficult to quantify due to site conditions (wind currents, sunlight, etc.) and the vagaries of annual climate cycles, the reduction of shake surface exposed to drying reduces long-term service. A yearly removal of this debris would increase the effective durability of the shakes, and increase a beneficial degree the service life of this material.

    When a shelter does need to be re-roofed, the build-up of moss and plant growth can be significantly retarded by installing an inter-ply sheet of zinc in one or two courses of shakes. Periodic debris cleaning of the roofs would still be required, but the zinc would prevent plant and moss growth from occurring.

    Recommendation

    1. As part of an annual maintenance program, sweep the shake roofs of accumulated debris and moss.
    2. Consider zinc inter-ply sheets during re-roofing projects.


1   Former NPS employee Jack Nattinger recalls in the 1950's that district ranger Jack Broadbent wanted to build shelters with a view and would go to the site of a new shelter and selected the site himself, and then have the carpenter build the shelter in a specific direction; see Oral Interviews with Jack Nattinger and Ted Sullivan by Paul Gleeson, NPS, September 27, 2007.
2   See structural analysis by AHJ Engineers in Appendix 3 of this document.


Shelter Development spacer Table of Contents spacer Shelter Development Period 1