Prefab vs. Custom: What’s Cheaper for Small Steel Buildings?

When you’re shopping for a small steel building—whether it’s for a workshop, garage, or backyard business—cost is almost always the first concern. I’ve had hundreds of conversations with customers who start by asking, “What’s cheaper—prefab or custom?” And while the short answer is prefab, the real answer depends on what you’re building, where you’re building it, and how flexible your needs are.

I’m Jason Caldwell, a graduate of Texas Tech University with a degree in Construction Engineering. I’ve owned and operated a metal building company in Oklahoma for over 15 years and write for Price It Here, where I help folks like you make smart, budget-friendly decisions about steel construction. In this post, I’ll walk you through the key differences between prefab and custom steel buildings—and help you figure out which one gives you more bang for your buck.

What Is a Prefab Steel Building?

Prefab (short for pre-fabricated) steel buildings are factory-built kits that are manufactured off-site and shipped to your location for assembly. These kits come in standard sizes and layouts, with most of the design work already done. They’re engineered for quick construction and cost-efficiency.

These buildings are often used for:

• Garages

• Workshops

• Agricultural storage

• RV or boat shelters

• Backyard businesses or hobby spaces

If you’ve seen a clean-looking metal building go up in a matter of days—that was likely prefab.

What About Custom Steel Buildings?

Custom steel buildings are designed from the ground up to meet your specific needs. This can include unique dimensions, window and door placements, load-bearing specs, insulation packages, or even multi-use sections under one roof. They’re often engineered to meet local zoning codes, snow loads, or wind ratings specific to your region.

Custom doesn’t always mean extravagant, but it does mean you’ll have to pay for the extra time, design work, and material planning involved.

Let’s Talk Price: Prefab Wins on Cost (Mostly)

In almost every case, prefab steel buildings are cheaper than custom builds—sometimes by 30% to 50% less, depending on the size and features.

Here’s why:

• Bulk manufacturing: Manufacturers produce prefab kits in large quantities, which reduces cost.

• Standard designs: You’re not paying an engineer to draw up new blueprints from scratch.

• Faster installation: Crews can assemble prefab buildings in a fraction of the time, saving labor costs.

• Less waste: With pre-cut materials, you avoid the cost of excess steel and unused components.

A basic 20×20 steel garage kit might cost you $6,000 to $9,000 prefab, while a similar custom version could easily run $12,000 to $15,000 or more, depending on the finishes and reinforcements.

When Is Custom Worth the Price?

Even though prefab is cheaper up front, custom buildings can save you money in the long run—if your needs are complex.

Here are a few examples where custom might be smarter:

• You need a multi-use layout (like a shop on one end and an office on the other).

• You live in an area with strict zoning laws or high snow/wind load requirements.

• You want the building to match existing aesthetics or branding.

• You need custom eave heights, mezzanines, or crane systems inside.

• You want to maximize square footage on a unique-shaped lot.

In these situations, prefab might not offer the flexibility or performance you need—and a one-size-fits-all solution could create more limitations down the road.

How Labor and Site Prep Affect the Budget

Here’s a detail many buyers overlook: the foundation and site work can easily match or exceed the cost of the steel building itself—especially with custom jobs.

Prefab kits often require simpler slabs and anchoring systems because they’re lighter and engineered for easy assembly. Custom buildings, on the other hand, might need deeper footings, reinforced pads, or specialized construction permits. If you’re trying to save money, prefab will usually come with less expensive labor and fewer permitting headaches.

What About Quality?

You might assume prefab means lower quality, but that’s not true anymore. In fact, many prefab buildings are made from galvanized or red iron steel, just like their custom counterparts. The difference is in the flexibility of the design—not the strength of the materials.

Still, custom buildings allow for:

• Higher snow and wind loads

• Architectural upgrades

• Advanced insulation systems

• Heavy-duty internal support for cranes or machinery

So if you’re building something that has to take a beating—or if aesthetics really matter—custom could be the better long-term investment.

The Bottom Line: Choose Based on Use and Timeline

If your goal is to get a durable, functional building up quickly and affordably, prefab is your winner. It’s ideal for small businesses, farmers, mechanics, or homeowners who want a fast and clean build that doesn’t require architectural finesse.

But if your project involves special zoning, high traffic, or future add-ons, custom might be worth the extra cost upfront—especially if you’ll be using it daily or for revenue-generating activities.

Here’s how I typically advise my clients:

• Go prefab if you want quick delivery, basic storage, or a low-cost workshop.

• Go custom if you need multi-use functionality, structural upgrades, or design flexibility.

Steel Building Buyer’s Checklist: What to Know Before You Buy

If you’re serious about investing in a small steel building—whether prefab or custom—this checklist will help you avoid budget overruns, permit issues, or regret down the road.

Know Your Purpose

Ask yourself:

• What will the building be used for? (Storage, workshop, office, retail?)

• Do you need insulation, electricity, or plumbing?

• Will it need to meet specific wind/snow load requirements?

Set Your Budget Range

• Include the cost of the building kit or custom design

• Account for foundation and site prep

• Don’t forget permits, delivery, installation, and add-ons

Measure Your Space

• What’s your lot size and shape?

• Will the building fit with adequate clearance on all sides?

• Is the ground level and accessible for trucks and crews?

Check Local Zoning and Building Codes

• Are there restrictions on building height, use, or appearance?

• Do you need a permit or engineer-stamped plans?

• Are prefab kits pre-approved in your county?

Compare Prefab vs. Custom Specs

• Does prefab meet your size, layout, and load requirements?

• Will a custom build offer long-term value for business use?

Evaluate Lead Times and Delivery Options

• How fast do you need the building?

• Will the supplier ship to your location and include unloading help?

Choose a Reputable Vendor or Builder

• Check reviews, licenses, and warranty coverage

• Ask about included support, from design help to construction coordination

• Get quotes from at least 2–3 vendors

Confirm Installation Details

• Will it be a DIY build or professionally installed?

• What are the labor costs in your area?

• Who’s responsible for concrete or foundation work?

Plan for the Future

• Will you need to expand the building later?

• Does your design allow for future add-ons, doors, or interior changes?

A steel building can be one of the best long-term investments you make—if you plan it right. Whether you go prefab for simplicity or custom for performance, taking the time to check off each of these boxes will help you stay on budget and avoid delays.

Written by Jason Caldwell, a Texas Tech University graduate with a bachelor’s degree in Construction Engineering. I’m the owner of a successful metal building supply and construction company in Oklahoma and a contributing writer for Price It Here. For the past 15 years, I’ve specialized in helping businesses and landowners build cost-effective, high-performing steel structures that last.

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