[dzobrist]

I want to get suggestions on this idea I had. I've attached a drawing of my design since it's difficult to express in words. I want to build an L-Shaped planter box large enough to construct an L-shape bench on the inside corner, attached to the planter box. I also want it to be bi-level. I'm thinking the length and width will be about 10-13 feet and the first level 4 feet high and second level 5.5 feet high. See attachment to help visualize.

So I need some tips and advice:
1) I was going to use pressure treated wood. Good idea?
2) Should I line the inside of the planter box since it will be filled with dirt to make it last longer? If so with what?
3) I live in Chicago so I'm worried about the frozen winter. Should I spend the time to dig and build a rock base to ensure the planter doesn't shift around? I would not like to do that since that will take a lot of time. Another alternative I was thinking about was digging and creating a base where the posts are at.
4) Same issue as above. What about the soil within the box. When the ground freezes and expands do I have to worry about the soil bursting out?

Any suggestions on materials, design or construction is appreciated!!:thumbup:

 

[user1007]

Lost you on the height part of it. 4-5'6" seems awfully tall for bench seating? Did you mean to elevate just the planter portion with seating at the usual height?

 

[dzobrist]

The bench itself will be attached to the planter box probably at the 3 foot level. The additional height is so the wall of the box will be a backrest of sorts. The second level terrace is built on top of the first level so that will add another foot and half. On my drawings I tried to label the bench and tried to draw it about the middle of the first level planter box wall.

 

[woody4249]

You have a lot of weight in that.........."planter box" did you call it?
You need to be looking at tips on how to build a dockside retaining wall on all six sides. They use pressure treated 6x6 posts or larger and 2x6 boards tied together with lag bolts or coach bolts.............that things a monstrosity ....It'll have to have it's own zip code

Mike

 

[Millertyme]

Keep in mind you don't need to fill the hole box with soil. Just build a bottom about 8" from the top and fill it with soil. That will solve most of your issues. Pressure treated will work fine, bit cedar is better, but more expensive.

What happened to your picture?