Building a Bridge on a budget

Reply

  #1  
Old 03-06-19, 12:17 PM
K
Member
Thread Starter
Join Date: Oct 2018
Location: usa
Posts: 6
Received 0 Votes on 0 Posts
Question Building a Bridge on a budget

So I have a 1 acre pond that narrow near the house and I want to build a walk bridge about 5' wide to cross the pond. The span is about 40'. So I was going to put a support at the mid point of the span anchored into the bottom of the pond. I was thinking of using treated 2 x 10 x 20 and carriage bolting another 20' across where the board butt up to each other.to cross the span using 5 runs 12" on center. Do you think that will be enough to support say 2-3 people walking on it at the same time.
 
  #2  
Old 03-06-19, 12:23 PM
XSleeper's Avatar
Group Moderator
Join Date: Dec 2004
Location: USA
Posts: 26,820
Received 853 Votes on 781 Posts
Never done it but if I was going to I would use 55 gallon barrels as flotation devices... build reasonable sized sections like a pontoon and then just tie them all together with steel cable that is anchored to turnbuckles on concrete piers on land and let them float.
 
  #3  
Old 03-06-19, 12:23 PM
M
Forum Topic Moderator
Join Date: Mar 2005
Location: USA - N.E.Tn
Posts: 47,937
Received 383 Votes on 339 Posts
I doubt a doubled up 2x10 would work well spanning 20' If you intend to use wood I'd think you'd need a lot more posts throughout the pond, not just one set in the middle.
 
  #4  
Old 03-06-19, 12:45 PM
W
Member
Join Date: Feb 2006
Location: USA
Posts: 6,748
Received 27 Votes on 25 Posts
5 runs 12" on center.
You will need 6 runs for a 5 foot wide bridge 12" on center.
 
  #5  
Old 03-06-19, 12:55 PM
P
Group Moderator
Join Date: Mar 2003
Location: NC, USA
Posts: 24,717
Received 786 Votes on 723 Posts
A floating bridge will likely be your easiest and cheapest. It can be built in small manageable sections and almost everything can be a human movable size.

You can build it like a boat dock. It's a method of construction that is used on lakes and seashores all around the country so there is a lot of information available on "how to".

Another option is to get the frame rails used under mobile homes. When old single wides are scrapped the frames underneath are available for a decent price. They could span 40' if you are able to transport and handle steel of that size and weight.

Do not attempt to do a single or double span with regular dimensional lumber unless you break it up into three spans. One span is simply too much. Two spans is at the limit of what regular lumber can do. You can also consider trusses or go to glue lams or LVL's.
 
  #6  
Old 03-06-19, 05:02 PM
Marq1's Avatar
Member
Join Date: Sep 2016
Location: USA MI
Posts: 7,122
Received 462 Votes on 430 Posts
Our bridge is made up of (4) 2x12x24' which span a distance of around 22'.

So if you can get a very solid center support then yes it's possible.

However, my bridge is only about 24" wide with deck boards so for 5' wide you will probably need (6) 2x12x24.

Here is picture in prior post!

https://www.doityourself.com/forum/d...en-bridge.html
 
  #7  
Old 03-08-19, 05:49 AM
K
Member
Thread Starter
Join Date: Oct 2018
Location: usa
Posts: 6
Received 0 Votes on 0 Posts
Thank to you all this is very helpful
 
  #8  
Old 03-08-19, 07:36 AM
K
Member
Thread Starter
Join Date: Oct 2018
Location: usa
Posts: 6
Received 0 Votes on 0 Posts
My Idea using some of your information. Again only a walk bridge with 6 runs 12" on center for a 5' Wide 40' long bridge
 
Attached Images  
  #9  
Old 03-08-19, 11:21 AM
P
Group Moderator
Join Date: Mar 2003
Location: NC, USA
Posts: 24,717
Received 786 Votes on 723 Posts
When you said 5' wide it didn't sound like a walking bridge. That's wide enough for golf carts, Gators and small tractors. I was concerned about heavier loads.
 
  #10  
Old 03-08-19, 11:33 AM
H
Member
Join Date: Nov 2012
Location: USA
Posts: 2,007
Received 149 Votes on 130 Posts
Originally Posted by marksr
I doubt a doubled up 2x10 would work well spanning 20' If you intend to use wood I'd think you'd need a lot more posts throughout the pond, not just one set in the middle.
Well, you CAN span a 20' gap with lots of eight foot long 2x4s, if you do it just right...

https://www.youtube.com/watch?v=vn-N172cPbY





https://www.pbs.org/wgbh/nova/lostem...na/builds.html
 
  #11  
Old 03-10-19, 06:41 AM
K
Member
Thread Starter
Join Date: Oct 2018
Location: usa
Posts: 6
Received 0 Votes on 0 Posts
Walking bridge

I figured allot of people assumed I would be driving on it actually the initial purpose is me walking my daughter across it for her wedding
 
 

Thread Tools
Search this Thread
 
Ask a Question
Question Title:
Description: