Last weekends project and some questions

[farmerbw]

Not really woodworking per se, but a fun home project. :gar-Bi

So LOML and the kids have been asking for a bridge to cross the creek in our backyard for a while now and I finally bit the bullet and stopped over planning and just built the thing finally!! :gar-La; It probably took me about 15-20 hours over the course of 3 or 4 days to get it done and as you can see the kids are already enjoying it. I still have to back fill and level the areas leading up to the bridge and that's where my questions come in.

The frame is 4'x12' built from treated 2x8's, 3 12 footers cross braced every 3', and the decking is 5' treated 5/4. I used Kreg Blue Kote pocket screws for the framing and added galvanized bracing and corners just for good measure. I assembled the frame in front of the garage, instead of carting power tools to the bottom of the yard, and once assembled loaded it in the bed of my truck and drove it down the street to the side yard and then drug it across the yard. I dug down and leveled concrete pavers to set the frame on, used a swing set anchoring kit to, hopefully, secure all four corners and then installed the decking. We wanted something a little different and tried to duplicate a kit bridge we saw a picture of. In order to get the zig-zag I alternated the decking over hang from 2" to 10" in 1" increments.

Now for the questions/issue. I completely forgot that I wasn't using burial rated, if it even still exists since Lowes doesn't carry it, treated for the framing so now I have to decide what to back fill with so the frame isn't in direct contact with the soil. Or does it even matter? I don't want to have to be pulling the decking off and redoing the frame in a couple of years due to rot. Can I back fill starting with gravel and then add soil separated maybe by landscape fabric to keep it from migrating? Will that encourage drainage enough to keep the wood from staying damp and slow down decay? Can I paint or treat the treated with something and then just back fill with soil? I'm open to all ideas and suggestions at this point.

TIA,
Brian.

 

[lbtripp]

Brian,

Good looking bridge.

How about treating the ends of the bridge with a protective coating. I used to use creostoe years ago. I don't know if it is available anymore. But they must make something you can use. Ask at the paint store. Then lay up some concrete pavers a couple of inches away from the ends and then backfill the pavers with soil. That way you can still get to the ends a few years down the road if needed. The space will allow air flow around the ends.

If you are worried about the gap you could use a wider board on the end that would come closer to the pavers which could be removable for future end treatment. :eusa_thin

Lyell

 

[DaveO]

Personally I would just ramp down the ends with some more lumber or leave it as a step up. Even though your PT lumber isn't rated for ground contact, you will get at least 10 years out of it before it starts to rot. I have a raised garden bed built out of non-ground contact PT lumber and it's just fine after 10 years.

Dave

 

[farmerbw]

Lyle, interesting suggestion. Definitely something to look into but I think creosote wouldn't be good to use for this application since the bridge will get submerged quite a bit.

Dave, I was actually thinking about using some let over treated 2x to ramp out in front like you mentioned in hopes that it might help reduce wash out when the water gets high. If I can get at least 10 years out of the treated 2x's directly buried then I may just got ahead and back fill with the soil and rock that was excavated and see what happens. I was mainly concerned about longevity because last week I was digging through some of the KDAT deck leftovers I had saved and found that all the 6x, 2x, and 5/4 stuff that was laying on the ground had already rotted beyond use after not even 2 years. Maybe that was due to it getting covered in leaves and pine straw and staying damp all the time. :dontknow:

Thanks for the suggestions.

Brian.

 

[Mike Davis]

Why not backfill with gravel? The gravel will drain well and keep the lumber off ground contact.

I would anchor better if that creek floods much. Some 3/4 inch rebar driven 6 feet in the ground might keep it from floating away.

 

[farmerbw]

That looks like an option I'll do Mike since I've also got some leftover gravel. As for the anchoring..... I've got a 22" swing set twist anchor lag bolted with galvanized straps at each corner of the bridge but am seriously considering adding some longer sections of rebar I've got on hand with some chain or cable to keep it from floating away just in case the anchors aren't enough. Unfortunately we've got lots of rock in our soil so driving something that long may be a challenge.

Brian.