# Boardwalk height/width limitations



## pmdishwash (Jun 4, 2010)

With all of the insurance talk these days, I just wondered if any of you have received feedback on a minimum width/maximum height for boardwalks on your trails? My club is looking to build a series of short boardwalks to get through a low-lying area that gets pretty soupy in the spring. Is a 30" width too narrow? 24" height too tall?

I realize there are probably case-by-case, insurer-by-insurer variations to this rule, but I was just looking to see what you all were hearing from your insurers and/or land managers.


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## TFitz (Jun 21, 2008)

Short answer: it depends. I've heard nothing from insurers, but land managers in Puget Sound country seem to be OK with a variety of approaches. Questions: first, how much does the water level fluctuate in the low-lying areas? Do they just get sloppy, or are they subject to real flooding? It would be worth knowing how much height is needed to keep the tread above water in the worst-case scenarios. Second, how firm is the ground when wet? Can you use plain old pier blocks as sold by Home Depot or Lowes, or do you need to "float" the boardwalk on big logs? Third, what building materials will you use? If using standard sizes of treated lumber and the boardwalks are short (I'd say less than 30 feet, but that's just me), I'd say a 32" tread width is good: you can cut the boards from standard 8-ft lengths without any waste. At that width, 4X6 or 4X8 stringers (can be doubled 2X if you want) spanning every 10-12 feet will work.


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## Loren_ (Dec 3, 2006)

Only insurance queries I've answered were related to height above ground, not width. 36 inches seems to be the magic number where more risk is perceived.

IMO, width should be driven by sightlines and length. If it's short and clear, narrow works fine - riders, runners, and hikers can see each other and avoid conflict. For me, anything more than 100' or so in length needs to be wide enough so that a bike and pedestrian can pass each other without someone going swimming.


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## Trail Ninja (Sep 25, 2008)

My LM would OK 36" width at 24" height. I could get away with as narrow as 24" with toe rails. Any higher than 30" would have to have handrails. All the trails in those parks are MUT.

Oddly enough, this is legit even without the handrail.


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## Summit Ridge Guy (Aug 16, 2010)

pmdishwash, is your proposed 24 inch height based on the need for fluctuating water/mud levels or to create a more tech feel for your board walk?


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## thefriar (Jan 23, 2008)

Ninja, I love that trail.


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## pmdishwash (Jun 4, 2010)

The 24" height was more of a hypothetical. It's likely going to be lower than that, as the water levels aren't flucuating/running. Actually, the area is essentially just a low spot that takes forever to dry out in the spring and after rains. There's no real alternative for a reroute, and reinforcing the trail in other ways has proven ineffective. I'm thinking that we'll have no issue with a boardwalk at 24" or lower, but I just wanted to hear if anyone had recent feedback from insurance co's or land managers that would change what has been commonly accepted.


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## Markhpnc (May 5, 2011)

Lots of good advice given.

The Whistler Trail Standards document and IMBA Difficulty Rating also provide some good solid guidelines for bridges and TTFs. Added benefit that you then have documents to actually reference if questions or issues arise from land managers or insurance.

Basically it's 36" width for green and 24" for blue. For blue and black they also add some ratios for width/height.

The WTS go into a bit more detail and I'll try to upload those in a minute. [Edit: file is too big here's a link http://www.whistler.ca/images/stori...g_Committee/trail_standards_first_edition.pdf ]

Hope this helps!


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## TFitz (Jun 21, 2008)

Since you don't have to worry about flooding, I'd go with pier blocks and dimensional lumber. Keeping the tread height low will also make the structure more stable. 32-36" wide tread should need only two stringers (4X6 or doubled 2X6's) spaced 24" o.c. between each pair of pier blocks for a solid-feeling structure. Use 2X6 or 2X8 tread boards, about 1/2" apart, roll a strip of tar paper across the tops of the stringers, use either rough galv 16d nails or 4" deck screws to fasten the boards to the stringers; should last quite awhile.


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