Joy worked in construction for 7 years alongside her husband (25+ yrs. experience)—working on pole barns, grain bins, and barn repairs.
Completed First Grain Bin Ring
Overview of Process
Start With the First Ring of Sheets, Then the Roof
When building a grain bin, you start with the first ring of sheets, then the roof. After that, you add on rings of sheets, working downward and lifting the bin as you go. The upper sheets are a lighter gauge than the lower ones, and must be put on in order. Bolts with neoprene washers are provided by the manufacturer, also nuts and most other needed hardware.
Remaining Rings of Sheets
The lower sheets are installed one ring at a time, with proper lapping. A sealant in a rubbery tape form, called mastic, is applied at the seams. Drift punches are used to help lift and align the sheets. An impact wrench and box end wrenches are used to tighten the bolts. Tightening is a two-person job, with the impact wrench operator being inside the bin, and the other person outside, holding the bolt heads still with the box end wrenches. This job requires strong wrists, good dexterity, and good mobility.
A bin 18 feet tall (6 rings tall), and 18 to 21 feet in diameter, takes an experienced crew of 2 men about 2 to 3 hours to erect with a boom truck or crane, or about 5 hours with jacks. This does not include site preparation, anchoring and sealing of the bin, breaks, interruptions, or add-on features such as fans, augers, and drying floors.
A medium-large bin may take 2 to 3 days, especially if other regular jobs must be maintained meanwhile.
Early morning is often the best time to build bins in warm weather, and is usually one of the safest as far as wind patterns are concerned. My husband and I have often started before sunup, and worked until mid-morning or perhaps 11 am. before the wind or extreme heat became prohibitive.
Tips and Tools
Tools Required for This Stage
- Drift punches, medium length (10 inches at least)--1 minimum for each crew member
- 9/16-inch box-end wrenches (2 at least), with long handles
- High quality impact wrench, as you will give it a work-out
- Hearing protection--preferably ear-muff or electronic type
- Work gloves which allow for dexterity (optional)
- Comfortable work boots with decent tread, hard toes optional
- Work clothes which will not snag or allow you to get hurt easily
- Tool pouch/apron, or coffee cans/small buckets for hardware (a small pouch is annoying as it must be refilled often, and is hard to reach into)
- Mastic (a sealant for between sheets). Mastic can be found using the search words: Single Bead Tape Roof Sealant Metal Sales
Anchoring the Bin Between Sessions
If you must leave the bin for more than a few minutes, either after the first ring is constructed or after the roof is together, you must anchor it or devise a way to hold it down.
T-posts may be used. Drive them in around the bin at intervals, using 4 to 6 posts for a medium-size bin, and wire them to the bin through bolt holes. Of course, this method necessitates moving the bin off the concrete pad first.
If you are using a crane or boom truck, lower the boom on to the hole at the peak, if possible leaving the bin in a position in which it cannot be much affected by wind.
Finally, if you are using A-frame jacks which are bolted into the bin, lower the bin to the ground and secure it using the jacks.
Where to Start?
Most often, the sheets are stacked in order. But occasionally, the second ring is on top. If you are unsure, the instructions which come with the bin from the manufacturer should tell you whether the first or second ring of sheets is on top in the stack. The sheet displaying the name-brand will be assigned to either the first or second ring, so you can tell this way.
Some sheet styles lap well only one direction. Others are more versatile. Once again, the instructions should specify whether you need to lap clockwise or counterclockwise, facing in or out.
Beginning to Build the First Ring
Installing Bolts and Nuts
Installing hardware is simple enough that a child can help. Keep bolts in a bucket or large tool pouch so it is easy to grab handfuls without fumbling, or scraping your knuckles. The person plugging the bolts needs to keep pace with the one installing nuts. Aim for a balance between rushing ahead and making the person with the nut bucket wait.
Plugging in Bolts
Hardware Tightening Specifications
How much to tighten the nuts is determined by the size and grade of bolts, as well as their position. Please refer to your manual for torque specifications.
For this bin, the wall bolts were 3/8-inch, and their steel quality was 5 grade.
⅜-inch 5 grade=38 foot pounds.
In general, you want to tighten the nuts until they are singing soprano.
Listening carefully will soon allow you to determine by sound how much is just-enough versus too much torque. Try not to strip bolts, but don't under-tighten them, and so give yourself problems in the future. Leaks are no fun to fix, and nobody wants spoilt grain (or a leaky grain bin home).
Impact Wrench Tips and Notes
Basics for This Job
With a high quality electric impact, you should be able to tighten 3 nuts per second or more during re-assembly. Have a person on the outside with 2 box-end wrenches holding the heads of the bolts as you tighten the nuts. 5/16 nuts should only be tightened around 22 foot pounds, and I normally go a little more. 3/8 nuts should be tightened around 38 to 42 foot pounds. On a 48' diameter bin, the black impact socket will often turn cherry red by the time a ring is completely tightened. Remember, tighten the nuts, not the bolts. You may need good gloves and rags to hold on to the impact after a while, as the gun will get extremely hot.
Jepson impacts (now out of business), are my favorite brand. Their impact wrenches out-perform any other gun on the market. They do not seriously over-heat, and they take the abuse.
If you cannot find a Jepson, a DeWalt or Milwaukee are your second best options.
Electric vs. Pneumatic
On a big bin, both types of impact guns give problems. If you are working fast, a pneumatic wrench will get very cold or freeze up. This is extremely uncomfortable to hold, even if the gun still works.
Also on a big project, an electric impact will overheat and possibly fry. You may continue to use a hot gun by wearing gloves and wrapping the handle in rags so you don't burn your hands.
There is no good solution to these problems if you want to work fast.
Additionally, a pneumatic gun will not keep up with the demands of an experienced builder even with a decently big air compressor. The compressor will need to refill frequently, forcing the crew member to stand idle waiting for it.
We don't discuss battery-operated types because they are unlikely to keep up.
Idiot clips are roof attachment brackets which bolt to the top ring of sheets.
They come in two types, and are normally installed with a long one beginning at a seam, followed by two short ones, then a long. If your bin brand deviates from this, the pattern should be specified in the instruction manual, or become obvious by examining the roof panel high ribs.
Installing Roof ("Idiot") Clips
Impact Driver vs. Impact Wrench
Previous and Next
- Site Preparation for Building a Grain Bin: a Discussion
This discussion is born out of the experiences of a long-time grain bin contractor. Here we consider the many requirements of the building site itself, and the concrete or foundation for a grain bin. Includes advice for bins with and without hoppers.
- How to Build a Grain Bin--Roof, Peak Ring, Lid, Safety Ring, and Roof Ladder: An Illustrated Guide
Learn step-by-step how to build a small or medium size grain bin ("silo") roof (includes no extra components such as vents). Other sections of the bin are shown in separate articles.
This article is accurate and true to the best of the author’s knowledge. Content is for informational or entertainment purposes only and does not substitute for personal counsel or professional advice in business, financial, legal, or technical matters.
© 2020 Joilene Rasmussen