Published May 8, 2012

High Tunnel Construction Workshop Summary

By Sally Worley

Practical Farmers of Iowa hosted a two-day high tunnel construction workshop at TableTop Farm in rural Nevada, IA April 23-34. Thirty people came to consecutively learn and help construct a tunnel during this immersion workshop. -blog continues below gallery-


High tunnels are a hot item on Iowa fruit and vegetable farms, and for good reason—high tunnels can offer opportunities for farmers to significantly extend their season without supplemental heat, and also offer a protected environment during the main season. This has proven instrumental for Iowa farmers like Jill Beebout and Sean Skeehan from Blue Gate Farm near Chariton who relied heavily on high tunnel crops in recent years due to volatile weather events. Here are some records of their high tunnel schedules for the past few seasons: Winter Season 3, Season 3, Season 2, Season 1.

The cost to construct a high tunnel varies greatly depending on size and amenities chosen, such as single- or double-layer plastic, gauge of and space between steel beams, type of endwalls, hipboards, roll-up sides, vents, whether the tunnel is stationary or moveable, the list of options is substantial. TableTop selected a 30’X96’ moveable skid high tunnel with double-layer plastic, polycarbonate endwalls, metal hipboards, roll-down sides, endwall peak vents and heavy duty posts to endure winds on their rural Iowa farm. The kit, from Four Seasons Tools, cost about $20,000. TableTop received a cost-share from NRCS that will deflect approximately $6,000 of this investment.

High tunnel construction can run 80%-100% of the cost of the tunnel, depending on the crew. Four Seasons constructs high tunnels for customers at 80% materials cost, which would be approximately $16,000 in this case. The goal of this workshop was to provide attendees with enough knowledge to be able to construct a high tunnel on their own, avoiding construction costs.

The weather was idyllic for the two days of the workshop—brisk and sunny day one and unseasonably warm and sunny day two. Adam Montri from Michigan State University returned to Iowa to lead his third high tunnel build for Practical Farmers of Iowa. He has constructed over 100 tunnels, so brought substantial experience along with his friendly teaching style. Mike Bollinger, co-owner of Four Seasons Tools, also attended and helped lead the build, even though it was his birthday (thanks Mike’s wife and kids for sharing him on his special day)! The bulk of the attendees did indeed plan to construct a tunnel on their own farm in the near future, and  were a helpful and inquisitive group.

Unfortunately, the high tunnel kit arrived a day late, not allowing for time for Adam to prepare work stations and do some additional pre-workshop prep. Consecutively, some key pieces of the tunnel were missing. Adam reports that it is quite common for all high tunnel companies to send kits with missing pieces, which is a mystery to me; they are then responsible for paying the trucking fees to get the straggler pieces to the construction site quickly. Due to the inability to set up beforehand and the missing pieces, the workshop outcome of a completed tunnel was not met—attendees and the entire crew worked really hard, but the skin (high tunnel plastic) was not pulled by the end of the workshop. This is unfortunate, because this last step, while not the most difficult, is often the most daunting for people constructing their first tunnel. The workshop also lacked some of the more organized “teaching moments” our high tunnel builds have had in the past, due to a more scrambling pace these unexpected delays made. Adam Montri still was able to share a lot of good information, but he is truly an encyclopedia of high tunnel building, growing, scheduling, marketing and recordkeeping, so every minute he gets to share his experiences with high tunnels is valuable. Luckily, Adam is also a PFI member and friend, and some of his knowledge is captured in past farminars. Check out “Grow Better with High Tunnels” and “Growing in High Tunnels” in our farminar archive.

Regardless of the unexpected delays and not skinning the tunnel, attendees left with enough knowledge to embark on their own high tunnel build adventure. Build steps accomplished include: square house, assemble skids, stand bows, attach ridge cap and purlins, attach horizontal bracing, attach baseboards, attach hipboards, attach windbracing and assemble and construct endwalls. Since this was a full immersion event, attendees participated fully, from drilling hundreds of holes to reaching new heights while securing flashing at the peak of the Gothic roof.

As with all PFI events, the food, prepared by PFI’s own Tomoko Ogawa, was delicious, and the conversations and friends made priceless.

Laura Miller from the Leopold Center for Sustainable Agriculture created a nice photo slideshow of the event.

WHO-TV 13’s Megan Reuther also aired a nice news feature about the event.

Michael Crumb of The Ames Tribune published a nice article about the event.

Thanks to the Leopold Center for Sustainable Agriculture and the Ceres Foundation for providing funds to be able to hold this workshop.