Final Design and Lumber Trip

There were still a few things to figure out for the platform. The heart of the platform is two 16' beams. We tossed around all kinds of ideas: Rough sawn lumber, reclaimed beams from old buildings, built up beams, engineered beams, etc.

We knew the structure would sit out in the elements over the winter, so it had to fair well in wet weather, that ruled out a few options. We didn't want it to warp as the timber dried, that threw out the rough sawn beam idea.

After some advice from our friend Tommy who had a lot more experience doing this kind of thing then we did, we went with the built up beam idea. We'd use two 2" X 10" X 16', with a .75" layer of plywood sandwiched in between for each beam. We figured the plywood would add support to any weak points in the beam. Each beam would be suspended from two points, with about a 10' span between suspension points.

After changing our minds several times over a few months, we settled on a in-frame floor joist system. Originally Dad thought that the joists should sit on the frame, but he came around to hanging the joists inside the frame. It helped solve a few problems: the plywood floor on top of the joists would help keep the frame square removing the need for cross braces. It saved us from buying two more 16' pieces of lumber to use as joist caps. We also didn't have to worry about hurricane clips, or other methods of ensuring that the joists would stay on top of the beams.

With these decisions made, we updated the drawing, and calculated how much lumber we'd need. We decided to go with preassure treated lumber, since it would be exposed to the elements, at least for several months.

We rolled down to the local lumber yard, and spent a good amount of time picking out the straightest and strongest looking lumber. We went through every piece of lumber that was apporpriately sized.

I was amazed at how heavy treated lumber is. I was also surprised by how expensive it is. The lumber plus a bit of miscellaneous hardware totaled about $500. Ouch. Hopefully this painful trend won't continue.