Construction Guidelines for Wooden Technical Trail Features
Source: IMBA Canada
Before You Start
• Make sure to get permission from your local land manager before starting any trailwork.
• All wooden technical trail features (TTF) should be carefully planned. Create a schematic design that shows the trail and all elements of the TTF including scale, location, dimensions, materials, fasteners, filters, fall zones, signs and optional lines. Get approval of the plan before beginning construction.
• All wooden features should be designed and constructed with the assistance of an experienced carpenter.
• The TTF should generally follow best management practices for exterior deck, staircase and/or pedestrian bridge design, construction and maintenance.
• Materials should be selected, installed and maintained for durability, strength, riding predictability, aesthetics and environmental acceptability.
• Select durable wood that is naturally resistant to moisture, decay, sun, heat, cold and insects. Some examples include redwood, cedar, white oak, cypress, locust and manzanita. There are also several environmentally friendly commercially treated woods that are extremely durable and weather resistant.
• Don't use wooden pallets, scrap lumber, plywood, soft woods such as pine, or other inappropriate materials that will quickly deteriorate or become unstable.
• Don't use dead trees, logs or stumps unless they are sufficient size or type of wood to withstand deterioration. Certain types of weather-resistant dead wood can be used if properly prepared by removing bark to prevent decay and following all construction guidelines.
• Do not use living trees in any way.
• Rough-sawn or hand-prepared wood will blend into primitive locations better than commercial lumber
• Wooden features should be stronger and more stable than the greatest anticipated force and weight. Use cross and diagonal bracing. The strength of the TTF shouldn't rely on the shear strength of the fasteners.
• The surface finish should be such that there are no protrusions or excessively sharp edges that pose a safety hazard.
• Decking should not extend more than a few inches beyond supports. For example, the decking on a ladder bridge shouldn't extend more than a couple inches beyond the stringers.
• Decking planks should be spaced slightly to aid drainage. Avoid gaps of greater than a couple inches in the riding surface.
• Use appropriate fasteners. Select high-quality screws, bolts and nails designed for exterior use. Fasteners must be strong, secure and corrosion resistant.
• If additional traction is required, add durable, predictable and aesthetically appropriate texture to the TTF surface. Some of the better methods include using wood with natural texture such as rough-sawn or hand split timbers, adding texture to wood by scoring with a saw, covering the riding line with anti-slip paint designed for exterior or marine use, or attaching diamond mesh lath (made from galvanized steel and used for stucco application). Chicken wire and roofing materials typically aren't durable.
• The approach to the TTF should be on dry and stable ground to help prevent water and mud from being carried onto the wood, which can cause deterioration and a slippery surface.
• Special attention should be given to abutments and places where the TTF contacts the ground. Wood should generally not touch the ground directly. Use foundation materials such as rock or pre-cast concrete footings to prevent dirt and moisture from deteriorating the base of the TTF.
• Consider pre-fabricating the structure at home. Be sure to make careful measurements in the field first.