How to Build a Shop
Typical Metal Shop Building
Why Build a Shop?
Shop Buildings and AG storage buildings save owners money in the long run. Money invested this year saves depreciation of equipment in years to come.
Select a Location for the Shop.
The best way to add any new building to your ranch is simple. First, draw your facility on paper. Then, draw in the proposed location of your new shop building.
Next, mentally go through all the processes that take place each day. It may be beneficial to use different colors to draw in vehicle paths for loaders, delivery trucks, milk trucks, and other machinery. Here are some things to consider:
Will any loaders or delivery trucks or milk trucks need to back up in the direction of the building? If so, you may want to consider another location.
Be sure a fire truck can turn down your drive and then make a complete turn without backing up. Every fire department requires this. Do not block any existing routes used by work equipment. Do not block fire truck routes.
Septic and water: Situate your building at least 100 feet from existing septic lines and from any wells on the property. This is best practice, and it is also code in most regions. Wells usually do not move. A septic tank can outlive it's leach lines however. For this reason, consider the future expansion of your leach lines. Sketch these on your map, and position the shop 100 feet from this reserved area as well. A few counties want to see this on plans submitted for construction permits. Most do not.
The process on how to build a shop involves much more than just building the shop itself.
Choose Size and Dimensions
Consider all the functions the new shop will serve. Estimate how much space you need. Then, add 20%. A shop building can last 20 years, easily. After this, you may need to replace some exterior panels. But, inside, you will have stored more than you expected. You will be glad for the extra space.
The first all-steel buildings went up only about 90 years ago. The service life of steel columns and rafters remains unknown. So, consider adding some room for future expansion. Who knows what your needs will be in 20 or 30 years?
Permits, materials, and labor only get more expensive with each passing year. Considering future needs will very likely reward you.
Caveat: Some counties now require "fire suppression" water reserves in order to approve new permits. This requirement is typically activated over a certain threshold area (e.g. 1,200 square feet and greater requires fire sprinklers or an 8,000 gallon water tank.)
Typical Steel Building Frame Detail
Fire Fighting Requirements
In the central California region, fire departments have begun to require fire fighting water. While I strongly disagree with the requirement to fight fires on a steel building, the requirement does exist. In most cases, the equipment and materials that will be moved into the shop already exist on other places and in other buildings of the ranch. No new fire risk is created. Yet, a water supply must be installed.
To avoid this, a building typically must be less than 1,200 square feet in size. This means something slightly less than 30 feet x 40 feet. 29' 9" x 40', for example, is 1,190 square feet, and will not trigger the water requirement.
Square footage is calculated using the area within the walls, or within the vertical columns for roof-only structures like cattle shades. Overhangs do not factor into the area used by either the fire department or the tax assessor.
To be certain if water storage is required, contact an engineer in the state where your facility is located, an engineer familiar with the process and the fire code, or your local fire chief.
One thing to consider, if you anticipate a future expansion, is the use of "wind frames" in the main wind force resisting system. These frames are typically of cold formed, light gauge steel "C" sections. For example, with 20' bays and no doors in the end wall, a 40' wide building can have an end frame using three vertical columns of 8" x 2.5" x 16 GA "C" purlins. These frames are also called "non-expandable frames". If an owner extends a building later, this kind of end frame must be removed, and an all-new, full force resisting frame must replace it.
So, when you build a shop, you must also consider future needs.
Wind frames resist their own vertical weight, but transfer wind forces to adjacent frames using cable bracing. Cable braces for steel buildings are often referred to as "X bracing" or "cross bracing."
If you will not expand, then wind frames save money on materials. Light gauge steel weighs less than standard pipe sections or W beams typically used in metal building frames. One thing all steel building owners must concern themselves with is heavy equipment traffic. A hauling rig or tractor can bow a C-section column, effectively denting the building. While this is uncommon, it is something to consider in situating a building.
Wind frames do not provide opportunity for expansion.
Most shop buildings will have concrete floors. You want to keep the floor serviceable for many years. If you build a good foundation, your children and grandchildren will be able to stand on it years after your retirement.
The single most important aspect is good compaction of the soil. Soil should be compacted to 90% or better. In very rare cases, a project might specify 95% compaction. This might be for a laboratory or for a facility operating sensitive equipment. It takes twice as much work to get from 90% to 95% as it does to get from open field to 90% compaction. So, it is not worth it if you don't have a specific need.
The specification of the concrete will be in "pounds per square inch," or psi, for short. Most concrete is poured as 2500 psi. Some counties now require 3000 psi concrete. But, this adds almost nothing to the strength or crack prevention capacity of the slab. Instead, add rebar to the slab. Most contractors who quote on your project will quote "5 sack" concrete. This is 3,000 psi. Many counties now require 3,000 psi specifications on plans submitted for building permits. So, this is becoming standard. This is an IBC 2018 code requirement (CBC 2019.)
(The perimeter of your slab should have a 12" x 12" perimeter footing all around. Reinforce this will two #4 bars. Place one 3 inches above the bottom, and centered in the width, 6" from either side. Place the other #4 bar 3 inches from the top, also centered. (A #4 bar is a one-half inch diameter steel bar. The 4 is the number of eighths of an inch in the diameter. A #3 bar is 3/8" diameter. A #5 is 5/8" diameter, and so on.)
If you pour an apron slab, deepen the perimeter footing to 18". As trucks, loaders, and other equipment and vehicles pass over the edge of the slab... over the years, the shallower 12” perimeter footing tends to crack and and sink like an eroding cliff. The 18" perimeter footing is the fix for this. These impact-edges also exist at roll-up doors that allow vehicles to enter the building for maintenance or storage. These portals also require an 18" perimeter footing beneath them to increase the service life of the slab.
These 18" perimeter footings should have (4) pieces of #4 reinforcement bars (rebar). Two are in the top and two are in the bottom. As before, they are 3 inches from top and bottom. But, they are spaced 6 inches center-to-center. And, #3 bar "stirrups" are added every 6 feet. A stirrup resists diagonal-lengthwise bending cracks. It is basically a hoop around all 4 bars. It starts and stops at the same bar using a hook. The hook is created by bending the bar 135 degrees (which leaves a 45 degree angle between the foot of the hook and the bar itself.)
As soon as the slab is poured, it must be scored with control joints (CJs.) These are typically the width of the cutting tool used and should be cut into the slab approximately one-fourth the depth of the slab. For example, the CJ in a 4" slab is about an inch. In a 6" slab, it is an inch and a half. The spacing of control joints should be no more than 24 to 30 times the depth of the slab. So, a 4" slab has a maximum CJ spacing of 10 feet. (4" x 30 = 120" = 10'). A 6" slab has a maximum spacing of 15' on center.
Most shop builders run electricity to the new shop. Show the main panel, and identify where you would like the new subpanel installed at the shop. Preferably, this will be near to where you plan to run equipment. New electric usage requires approval from your electric provider.
Solar: Solar power is being used increasingly by ranchers. Part of the reason is a big push by solar companies. Profit margins are extremely high. This means market forces should bring the cost down in coming years.
The reason solar appeals to farmers and agribusiness is that they already have the angled roof surface to host the panels. Installation of the additional load is not automatically viable, however. Have an engineer check your building to see if the additional 5 pounds per square foot will not overload the building design. I have checked several of these buildings in the last two years. The design of most of them was adequate. Two of the buildings required addition of knee braces to shorten rafter spans and transfer loads into columns more directly.
After your building is constructed, here are a few things to look for in your follow-up inspection. Every owner should inspect the building. Be sure to stipulate in your contract that some amount of the cost will be paid after satisfactory acceptance by the owner.
Check Your flange Bracing
One of the most important things is to check for flange bracing. Many contractors think these brace the roof purlins. They don't. Flange braces protect rafters, especially long span rafters and clear spans, from torsion. A steel rafter will deflect a certain amount. Then, it twists. Once it twists, it quickly fails. This is more of a concern in regions prone to snow.
The lower flange bracing should be present on any beam deeper than 12". If rafters are 12" or less (e.g. W10x12 or W12x26), purlin clips attached to the top flange serve to brace the member against torsional buckling. If members are deeper than 12", but the purlin clips are welded to the web to a point below half the measure of the web, then this also braces the member.
Pay attention to the cross bracing. The purlin run closest to every column should be braced. This is an American Institute of Steel Construction standard. A wall diaphragm qualifies as bracing in small, free-span metal buildings such as the typical 40 x 60 shop. Cross bracing also braces the connection node and transfers forces into the column.
The most common failure method to metal buildings is an unexpected snow load in conjunction with a contractor who failed to install lower flange bracing. One of the major pre-engineered steel building companies performed a review of three buildings that collapsed in a record snowstorm. The cause was the same in all three: no lower flange braces were installed by the local, private construction team.
Inspect the Laps
Inspect laps. One of the more common complaints is poorly joined laps. Self-tapping screws sometimes strip the hole. If not corrected with a wider screw, or otherwise plugged, this can let in some water in heavy weather. Take a visit inside your new building during the day. Close all doors. See any points of light? Check carefully along the laps of roof panels. Roof laps require a mastic inserted between two lapping panels to seal out rain. This is more important for roof pitches less than 3:12.
Steel possesses great bending strength. A strong wind or gust will deflect the building. The steel might creak or squeak. This is normal and not a cause for concern.
Check the Crack Joints
Crack Joints should be no more than 15' on center. You will find these indicated on the foundation plan, typically marked as "CJ". These are typically a quarter-inch deep. CJs prevent cracks in concrete from moving through the slab entirely. Cracks in concrete are very common and expected. A few cracks are not cause for concern. Any crack bigger than a quarter inch rates a call to your contractor or builder.
Informing Your Engineer
Make a Sketch
Your sketch does not need to make Michelangelo envious. Believe me, I get some sketches that would make a third grader giggle. All it needs is to convey the basic data. For some ideas on different designs to meet facility needs, see Steel Building Designs. Here are the minimum things the engineer needs to know:
An Example Sketch for the Engineer
Information to Convey to Engineer
Length & width
out to out
in to in; center to center
to top of roof
clear, below lowest point of rafter
1:12, 1.5:12, 2:12, 3.5:12, 4:12
Type of Construction
Wood, concrete, combinations
26 Gauge R-Panel
Corrugate steel, Insulated Panels
no slab, gravel
Preferred purlin material
light gauge steel "Z"
Sawn wood 2x
2x3070 man door & roll-up doors
hydraulic tilt-up (for aircraft)
5' x 10' @ 20' o.c.
one open wall
plan to expand in future
location of well & septic
separated by code requirements
Add area for future septic expansion
Owner knows it
Address not yet assigned
Owner knows it
Researched by Engineer
Owner has a copy
Engineer acquires from Assessor
Preparing for the Build
Once your design requirements and location are carefully determined, it is time to find a contractor and an engineer.
Your goal, before contracting with a builder, is to have a set of plans and a minimum of three bids. The best way to do this is to first hire an engineer. The engineer will determine the steel sizes for the main support system, purlins, girts, wall braces, flange bracing, and the foundation. The engineer will provide bolting and welding connection details.
You need two prices from the engineer. First, a price to provide engineering calculations and sets of drawings to give to contractors for bidding. Second, a price in the event the winning contractor wants to change connection details, or increase column or rafter sizes.
Changing the design is very common. Every contractor has a preferred method of connecting members. Some love to weld. They are expert welders, and this method means fast construction time, with no errors for them. Other contractors want to bolt their connections. The engineer will most likely provide a welded design. In the event the winning contractor prefers bolting, this requires an adjustment to the calculations and drawings. You want an up-front price for that eventuality.
Bolting is more expensive, and requires more labor. However, if engineered correctly, it can avoid a special inspection.
The engineer can also refer you to contractors and give you a little feed back on who are the better builders in the area.
Hire a Contractor
In 2011, I designed a series of shades for a remodel of pole building cattle shades on a dairy facility. It had been closed for three years. The owners there were experienced and professional. They requested I design those cattle shades (freestall barns) for future expansion.
Walking the sight with the contractor, he told me about his current job. An owner hired transient workers to build two roof-only shade barns. The project was dragging; it had been three months since the project started and very little work was completed. My contractor friend took over the project. His crew erected the buildings in about a week.
It may be tempting to think you can save money by managing the project yourself. And, you likely can. However, do not become a proxy contractor. Hire an engineer. Acquire drawings and engineering calculations for your shop building. Send them out for bids. Choose the best bid package, and hire the contractor.
Managing subcontractors can be an effective way to complete a project. But, managing untrained workers to construct a building will slow your project to a crawl.
Wood and steel contractors do not cross over well to the other material specialty. Hire a contractor experienced in building with the material you plan to use.
Get a Soils Report
Most of the reports you can buy are provided by civil engineers who specialize in soils. You can also look for a geologist. To find one in your city are area, find the website for the licensing board in your state. Use their "license lookup" service to search for engineers in your city.
There are two kinds of soils reports you will find available on the market. The most common type is produced using data from a USGS soils survey of the nation. The engineer locates your project site in this databank of maps, and notes the soil type. Next, he prepares a soils report discussing the properties of this soil, it's bearing capacity, and lateral capacity. The soils engineer also delivers recommendations for minimum foundation depths.
The second kind of soils report for a new building is conducted by analyzing boring samples. An engineer, an engineer's representative, or a team visit the proposed site. They take a number of borings. This number is determined by the minimum required in the local code, or by site characteristics, or even by the judgment of the engineer. These samples are sent to a lab. The lab report determines the bearing capacity, the coefficient of friction of the soil, and other characteristics necessary for the accurate design of certain structures.
Retaining walls, for example, can be built with greater factors of safety when the coefficient of soil is known. Some soils create greater lateral pressure. Others, because of the soil composition (sand, silt, clay, etcetera) exert more pressure vertically.
If several buildings are planned, a soils report has the potential to save money. The default bearing pressure is just 1500 pounds per square foot. A soils report will often deliver higher values. This reduces the size of footings. Savings in excavation, labor, and materials can exceed the cost of a soils report on large projects.
Some sites will always need a soils report
Anything located near a river, or in the historical overflow region of a riverbed, will have layers of fine organic silt. This reduces bearing capacity. Sites with a high water table should also have a professional determine the range of the water table. This will affect foundation designs and the design of retaining walls and basements.
Wall Purlin Orientation
When shopping a metal building, an owner wants to compare apples to apples. However, sellers have a way of making their apple a little smaller, while maintaining the appearance it is the same size.
Wall purlins (girts) may be situated between columns, in the wall line of the columns. Or, these may be placed on the outside of the columns. This is a loss of space. Effectively, the columns are moved into the working space of the shop. Lines of shelves must accommodate these protruding columns. Forklifts must avoid them. Parked equipment must stop short or move aside.
I have heard a few owners complain about this. So, it can become an issue with satisfaction. Consider it. The next two images show the difference between placing columns in the line of the wall girts and inside the line of the wall girts.
A PEMB seller wants to put the columns inside the girt lines. This shortens the span of the rafter by about 16 inches. That produces a small savings in the weight of steel. The PEMB market is very competitive, and they have to shave weight where they can. You must decide if the difference is important to your intended use.
40 x 60 Shop, Plan View, Columns in Wall Line
40 x 60 Shop, Plan View, Columns in Shop Floor Area
Which Column Placement is Better?
Where do you want the columns placed in your building?
Not all steel buildings restrict themselves to steel alone. Many use combinations of materials. Some owners like the idea of steel construction for the main wind and seismic resisting system, and then complete walls using 2x wood studs and wood sheathing.
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.