Forgive me for being a n00b and not knowing the answer already, but how do you create bars (like for a sewer, or to block off areas) out of scaffolding?
When I've seen it done, it's been by interlocking scaffolding items in a line so that the vertical pipes form prison like bars, sometimes including the same process but with the scaffolding pieces on their side, and the bars lined up vertically to make them form a grid with the horizontally lined up ones. To get rid of the wooden platform, either build the bars so that they merge in to a wall and ceiling at the top, thus covering the wooden bit, or flip the whole object upside down and merge it downwards so that the wooden platform is under the floor of the map and can't be seen. Hope this helps, if it doesn't explain it sutiably then I'll throw together a simple diagram in paint to show you what I mean. Or alternatively you could find a map that uses what you're talking about, then delete the objects surrounding the bars to see how they've done it.