Building a bridge over a pond

Jared Drake · November 20, 2007, 02:11:04 PM

I'm wanting to build a better bridge from the bank to the island in dad's pond. He says it's about 20 feet. Would I need any kind of support from the bridge to the pond floor for this? Any ideas or plans anywhere? Thanks. I love the new look.
Jared

peternap · November 20, 2007, 02:50:11 PM

I think you can build it with supports on either end Jared...Just so long as it's afoot bridge. I'd count on 30' so you'll have to lam up a couple of 2X10's for each side.

November 20, 2007, 03:13:29 PM

Jared... I'll have to see if I can scan one of our wedding photos and post here... we got married on a bridge our neighbor built over a little creek that ran through his yard... that bridge was probably between 20-30' long and very sturdy (we made the neighbor really nervous when my whole family piled on (around 200 of us) and took a group photo... If I can find one of the photos with a good shot of the bridge, it might give you some helpful ideas...

MountainDon · November 20, 2007, 06:20:58 PM

The forest service uses waterproof glu-lam beams. I've seen some in the 30+ foot range. Imagine they're pricey though. The ones that are especially nice are the ones that are set up with an upward curving arc. The ends are supported by heavy duty, concrete anchored footing. Very little bounce that way.

As Peter said you could likely make a bridge up with good 2x material. Waterproof glue, corrosion resistant fasteners, etc.

Before getting too far along in the planning, daydreaming, about how to do it you'll need an accurate measurement for the span.

Jared Drake · November 21, 2007, 02:36:11 PM

I can get accurate measurements this weekend, since I'll be out there. Really, all I'm doing is the work. Dad will be paying for it. So, if it can't be done without buying unbelievably expensive material, it probably won't be done. I'd like one with a low arch, not a flat one. There's a flat one there now with supports that are buried in the pond floor below the water. I'd like one that's unsupported. I'll reply back with precise measurements later. Thanks guys.
Jared

November 21, 2007, 02:44:14 PM

Jared, I have a 1910 book that has a small bridge made entirely of 2x6s except the deck and some braces so if you like when you get measurements I can post it for you. It is a low arch design.

Jared Drake · November 21, 2007, 11:29:42 PM

Thanks Glenn. Wow, I knew you were a bit older than me, but......did you buy the book new?
Jared

glenn kangiser · November 21, 2007, 11:45:29 PM

[eek] Jared, a bit older only.

No... I usually take a quick look in antique stores for old engineering, homesteading and machinery etc. books of interest.

MountainDon · November 22, 2007, 12:12:50 AM

Quote from: Jared Drake on November 21, 2007, 11:29:42 PMThanks Glenn. Wow, I knew you were a bit older than me, but......did you buy the book new?Jared

November 22, 2007, 12:20:14 AM

You are not helping things, Don.

mvk · November 22, 2007, 12:33:06 PM

Hi Jared
Don't know how much time effort or money you want to spend but how about a tension bridge? If you cut angles on some planking kind of like barrel staves and then attached wire rope on top. Then built a little pier foundation on both ends and attached the wire rope. and the built a railing. Seems like that would work. Just a thought. Betcha Glen could pull all this stuff out of a couple of piles around his place. If you lived near by I would come by and help, even bring my own beer.
Mike

glenn kangiser · November 22, 2007, 01:14:13 PM

You bet, Mike.

I have plenty of stuff to make a cable bridge too. Some day I may. I have rocks here I could anchor to but I figured Jared would need to build a big anchor at each end and I didn't think he was old enough to attempt such a complex project. hmm

Jared Drake · December 02, 2007, 03:47:41 PM

I'm old enough to throw anchors, but I'm not strong enough and it's not a real big sport around here. Besides, I have no ship.

Ok, my wife counted the deck boards from one side to the other of the bridge and there were 96 boards. That comes to 44 feet. Longer than I'd thought. I'll let you do the math. Deck boards are 5.5 inches, right? With 96 of them that comes to 44 feet. I'm beginning to think a low arch bridge isn't doable. Maybe some other type of nice looking bridge.
Jared

ScottA · December 02, 2007, 05:40:19 PM

How deep is the pond? Maybe you can do a zig-zag bridge on pilings.

December 02, 2007, 06:34:48 PM

You know, when I read your post, it dawned on me that last night I had thought of using the kinds of pilings that piers and boat docks are put on. I don't know why I didn't mention that in the post. But you'll have to explain what zig zag means in relation to a bridge. Oh, anybody know what kind of wood is used in piers?
Jared

ScottA · December 02, 2007, 06:46:21 PM

zig-zag bridge http://en.wikipedia.org/wiki/Zig-zag_bridge

Pressure treated posts rated for ground contact should work.

Jared Drake · December 02, 2007, 06:51:49 PM

I don't care for the zig zag thing, we just want a nice arch bridge to the island, which I believe that piers will achieve. Don't you think the pressure treated stuff would be toxic to the fish?
Jared

ScottA · December 02, 2007, 09:57:20 PM

I didn't think of them being toxic....could be. Maybe redwood or cedar?

MountainDon · December 02, 2007, 10:42:03 PM

do a search for the toxicity issue. I'd do it but no time tonight.

NorthernMich · December 05, 2007, 06:03:27 PM

so where are you located???

Building a bridge is way easier in winter believe it or not...well if the pond freezes that is

December 05, 2007, 06:52:10 PM

Quote from: Jared Drake on December 02, 2007, 06:51:49 PM
...pressure treated stuff would be toxic to the fish?

It could be... I couldn't find any info on fresh water use and potential toxicity.

There are some viable alternatives to PT wood. Depending on where you live, you may have access to a native species whose heartwood is decay resistant. Black locust, red mulberry, osage orange, and Pacific yew show outstanding longevity. Other highly rot-resistant species include catalpa, Arizona cypress, juniper, mesquite, and several oaks, namely bur, chestnut, Gambel, Oregon white, post, and white. $:-\$

Jared Drake · December 05, 2007, 11:59:25 PM

Don, I did a search and couldn't find anything about toxicity and treated lumber either. Well, at least not in regards to a pond. There's swamps down in south Arkansas, so getting cypress isn't really a problem aside from cost, which isn't a problem either because it's dad's money! WOO HOO!! We've got tons of red oak on dad's place. We call them blackjack, and I'm not sure if that's what you're calling a post oak but I'm almost positive it is. I might seriously consider a chainsaw mill for that project. Only thing is, I was hoping for something round, like you see in the movies when people walk down to the piers at the ocean. Any of you coast dwellers know what kind of wood is used for those?
Jared