Results 1 to 7 of 7
  1. #1
    mtbr member
    Reputation:
    Join Date
    Aug 2010
    Posts
    323

    Bridge building using a log

    I have a bridge that needs to be rebuilt since the stringers and decking is getting pretty rotten. The original bridge builder attached the stringers along the length of a larger ceder tree to provide a wider surface and then fastened the decking to the log and stringers. This makes a structurally sound bridge but it creates an area for organic material to collect up below the decking between the stringer and the log.

    My initial plan was to rebuild the bridge similar to the way it was initially built, but wanted to tap you guys first for some feedback. And yes I was to deck it rather than make a skinny.

    bridge 8.pdf

  2. #2
    Nouveau Retrogrouch SuperModerator
    Reputation: shiggy's Avatar
    Join Date
    Dec 1998
    Posts
    48,315

    Bridge building using a log

    Quote Originally Posted by Summit Ridge Guy View Post
    I have a bridge that needs to be rebuilt since the stringers and decking is getting pretty rotten. The original bridge builder attached the stringers along the length of a larger ceder tree to provide a wider surface and then fastened the decking to the log and stringers. This makes a structurally sound bridge but it creates an area for organic material to collect up below the decking between the stringer and the log.

    My initial plan was to rebuild the bridge similar to the way it was initially built, but wanted to tap you guys first for some feedback. And yes I was to deck it rather than make a skinny.

    bridge 8.pdf
    Add a second log for a more conventional two stringer bridge.
    mtbtires.com
    The trouble with common sense is it is no longer common

  3. #3
    mtbr member
    Reputation:
    Join Date
    Jun 2008
    Posts
    321
    question for the OP: is the log providing a significant amount of strength, or is it just in a convenient spot to position the stringers? If the latter, just use PT lumber and size the stringers appropriately (e.g. 2X10 or 2X12, not 2X4). If the log is structurally significant now, it certainly won't be forever.... Check in w/me via the Evergreen listserv if you'd like framing details on the bridge we built in Big Finn Hill Park 3 years ago; it has a 26-ft clear span.

  4. #4
    mtbr member
    Reputation:
    Join Date
    Apr 2012
    Posts
    100
    We built a small bridge out of a large diameter (12") oak log cut into two beams. Cut the log in half lengthwise and flattened the sides to make the decking and foundation more stable. All cut freehand using a chainsaw (even the decking). It took around 12 hrs total to build and would have gone much faster if we had a larger saw.

    Photos:



    The natrual curve of the log fits the dip it crosses.



    Bike for scale.



    Hand sawing the planks left a very rough and slip resistant texture on the decking.

  5. #5
    I build my own.
    Reputation: Trail Ninja's Avatar
    Join Date
    Sep 2008
    Posts
    5,285
    Build it like it was before but put spacers between the log and the stringers. Small blocks of 2X?. It will hold the stringers out from the log and crap will fall through.
    I have a device that can access the total knowledge of man. I use it to look at pictures of cats and argue with strangers.

  6. #6
    mtbr member
    Reputation:
    Join Date
    Aug 2010
    Posts
    323
    Good idea Trail Ninja. Thanks!!

  7. #7
    I build my own.
    Reputation: Trail Ninja's Avatar
    Join Date
    Sep 2008
    Posts
    5,285
    You're welcome. You'll still want to use treated or rot resistant wood because the blocks will eventually rot.

    It's wood. If you get 10 years out of it, you're doing better than most.
    I have a device that can access the total knowledge of man. I use it to look at pictures of cats and argue with strangers.

Similar Threads

  1. Building a bike & building a computer=similarities?
    By fatcat in forum California - Socal
    Replies: 16
    Last Post: 03-31-2013, 07:23 AM
  2. Replies: 17
    Last Post: 01-15-2013, 12:58 PM
  3. Building a pole bridge
    By RidingMyTrail in forum Trail Building and Advocacy
    Replies: 14
    Last Post: 12-07-2012, 11:18 AM
  4. The little bridge in CC
    By Hikers Only in forum California - Norcal
    Replies: 43
    Last Post: 04-05-2012, 08:28 PM
  5. New bridge at Annadel
    By GuruAtma in forum California - Norcal
    Replies: 12
    Last Post: 11-16-2011, 05:23 PM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •