Standards and Procedures:
Rock Steps and Staircases
A beautiful, meticulously crafted rock staircase in the Smokies National Park highlights the characteristics of great rock work. It is uncommon to be able to build major rock structures like this in the PRD due to NEPA rules.
A well-constructed stone staircase can be one of the most beautiful of trail structures, blending with the natural landscape while providing a stable, sustainable, and comfortable way to mitigate steep grades. The material doesn’t have the issue of rotting like wood, so well-built rock structures can potentially last indefinitely. Poorly built steps will fall apart long before they should, though, especially in a rainy climate like that of the Pisgah. Take the time to find the best rocks for the job and fit them together just right!
In the Pisgah Ranger District, the ability to build with rock is limited. This is mainly due to constraints stemming from NEPA rules, which prohibits us from quarrying rock out of the ground unless it is within the exisiting width of the trail. Harvesting rock outside the corridor requires additional NEPA surveys and approvals, a process which can take years and so must be reserved for major projects.
This document will outline the most important guidelines for building sustainable and user-friendly rock staircases that stand the test of time.
Key Points:
- Tools and Equipment
- General Specifications
- Notes on Staircase Design
- Construction Guidelines
Tools and Equipment
Recommended tools for building Rock Steps:
Basics:
- Rock bars (at least 2)
- Pick mattock
- Shovel
- Double-jack sledge hammer
- Single-jack sledge hammer (several)
- Prospectors pick/mini-pick/rapid-digger - for digging in tight spaces
- Cargo/rock net
- Drag slings
- Buckets or canvas rock bags for transporting gravel/crush
- Level
Optional:
- Carbide-tipped stone-shaping hammers and chisels
- Rotary hammer drill with carbide-tipped auger or chipper bits (gas powered, or electric with portable generator)
- Feathers/pins-and-wedges - sized to match your drill bit.
- Griphoist rigging setup for major rock projects
- Line level, useful in layout to estimate number of steps needed
General Specifications
- Install staircases in areas where the grade exceeds 12-15%, or where grade otherwise causes erosion problems.
- Individual steps should be no higher than 6-8.” Any higher and they become uncomfortable, leading to users avoiding them and causing trail braids.
- Use crushed rock or imported gravel for fill, not soil. Pack the crush firmly with hammers. Top with a layer of mineral soil. Steps should not wobble when jumped on.
- Start from the bottom and build up. Tuck each step behind the step below it whenever possible.
- Keep a tread length (or “run”) of at least 10-12” when possible. Step run length will vary depending on how steep the slope is, and on very steep slopes you may need to resort to shorter runs.
- Keep tread length (run) as consistent as possible for a comfortable staircase
- Step rocks should be large and heavy. If one person can lift it, it is not big enough.
- Bury the bottom step in your staircase completely. This may feel like a waste of time, but in the long run it provides a solid anchor for your entire staircase as well as an insurance policy against future erosion.
- Steps should be level from side to side and have a flat tread (stepping surface).
- Steps should be roughly as wide as the existing trail, in line with its trail class.
- Steps should have a very slight backwards tilt (batter). This increases stability and provides a safer step for hikers when conditions are wet or icy.
- Incorporate “gargoyles” on the sides of steps to guide users and prevent fill from washing out from around the steps.
- Gargoyles should be low-profile, large, stable, and not an appealing stepping surface. Don’t make the mistake of installing awkward-looking stalagmite or tombstone gargoyles that stick up way too high, as these look contrived and take away from the natural appearance of a stone staircase.
- Incorporate drainage just above the staircase.
- On trails with heavy mountain bike use, steps may not be the best option. Keep steps to a shorter height, or choose a method like Appalachian rock armoring instead.
Notes on Staircase Design
There are several suitable designs for how steps connect with each other in the context of a staircase. Some are better than others, but certain contexts may necessitate a certain type of step. Some staircases may incorporate multiple step designs depending on context.
Design 1: Tuck-Behind Steps
- Tuck-behind steps are generally the best way to arrange steps in a staircase. Each step is locked in place behind the step below it, all of which are supported by a buried base step anchor. This prevents undercutting or individual steps sliding out of place over time.
- Besides being very sustainable, this design enables you to take advantage of more oddly shaped rocks. As long as you have a flat face and a flat tread surface, then the rest of the rock doesn’t matter so much as it can be buried.
Design 2: Rock-on-Rock Steps
- Overlapping a step on top of the step beneath it is not as reliable as the tuck-behind design, but it can be useful in cases where you need to ascend a very steep grade and keep your tread length (run) shorter than the length of the actual rock.
- When building rock-on-rock steps, be sure you have suitably flat, rectangular rocks that stack cleanly with multiple points of contact. There should be no wobble, and rocks should be large enough and set far enough back into the slope that they will not slide.
Design 3: Vertical Steps
- Sometimes called “tombstone” or “toothed” steps
- This is the least desirable step design, but sometimes due to material constraints, or the context of getting through a tight spot, finding a flat rock and setting it vertically can be an acceptable step design.
- These steps must be buried at least ⅔ of their height underground (and crushed in) for stability. These steps are notorious for blowing out over time because often they are not buried deep enough.
Construction Guidelines
These procedures are intended to only provide a helpful reference guide. If you have never built one of these structures before, please learn under the guidance of an experienced trail builder.
A. Survey the Site
1. Assess grade and determine where to begin the staircase
2. Use line-level to estimate rise/run and number of steps needed
B. Quarry Rock
1. Use rock within the trail corridor. Dig off-trail in NEPA approved sites only.
2. Search for rocks with flat surfaces for tread and face
3. Find rocks with appropriate width for the trail
4. If one person can lift it by hand it’s not big enough
5. Dig/transport to site with rock bars, nets, slings, and/or rigging
C. Install Base Step
1. Bury the bottom step completely flush with the grade.
D. Install Steps
1. Tuck each step behind the step in front.
2. Pack crevices with crush/gravel.
3. Check level and batter on each step.
4. Install gargoyles to the sides of each step.
E. Repeat
F. Finish Work
1. Add/Tamp Crush Where Needed
2. Top exposed crush with mineral soil
3. Incorporate drainage above
4. Revegetate work area, including visible craters from quarrying
Good rock steps are wide, level, and consistent. They should be inviting to users and comfortable to walk. Note the gargoyles are large and well-set, just barely higher than the steps, and provide an unappealing step surface in comparison to the steps. Building steps well ensures that people will actually use them!