7.7 Select Trees for Use in Construction Select trees for trail construction from sites not noticeable from the trail, or use trees that must be removed from the trail right-of-way. Remove bark to facilitate drying. Prefabricate the required dimensioned lumber in the off-season. Select and use wood preservatives with care, if at all. Use construction practices that can help reduce decay. Build structures so that the ends of planks, stringers and posts are kept as dry as possible, since these points are the most susceptible to decay. When constructing bridge decking on stringers, avoid overlapping the ends of the stringers to prevent contact with the sill. Use a a treated wood spacer between the stringer and the sill. Also use spacers between the decking and foot railings to allow air circulation. Tilt railings and the tops of posts slightly so that water drains off. See also manual sections on wood structures construction.