Greenhouse, Episode #4

As I assembled the “tunnel” of the greenhouse from the cattle panel fencing I noted a lot of wiggle in the structure, even after tying all the sections together with zip ties at their edges.  Yeah, yootoobers swear it can withstand fierce winter weather but my friend Floyd over on the east side of the county, and whose greenhouse was absolutely the inspiration for this one, indicated that our occasional heavy snow (~18″) caused him some problems.  Being the over-builder that I am, I decided to add curved ribs inside the tunnel to beef it up.

My first step was to configure to tunnel to be symmetrical which required aligning the center of the arched panels with the center line of the overall structure.  Using a simple plumb bob I pushed and pulled the sections to be at least along the same center line.  I’d hoped that this combined with the rib-building process would make all the arch curves identical.

With string lashing to keep the arches aligned with the center line, along with diagonal wooden braces, I set about the task.

Using my little table saw more than I have in a long time I sliced off a pile of  3/16″ strips to build the laminations.  For the most part simply clamping the strips to the underside of the arches imposed a semi-circular arc, and this was enhanced by the continued build-up of the laminations.

A combination of spring clamps by the bushel, T3 glue and a multitude of crown staples the ribs began to take shape.  The enhanced structural robustness became increasingly clear as the glue dried, which took about three days given the moisture content of the PT SYP lumber strips and the weather itself.

All in all it took me almost three days to get the 10-layer ribs finished, but they are now in place for the next step, framing in the ends of the tunnels and adding doors and windows.

Seriously, the structure is now strong enough that I could crawl all the way to the top to staple the fence grid to the ribs.