A 30x40 Metal Building is a Great Solution for any Location

The 30x40 metal building is the 'workhorse' of the prefab kit building world, providing 1,200 square feet of column-free space. It is ideally suited for residential, farm, commercial, and outbuilding applications. All kits are manufactured to your specifications, are engineered for any location, and can be installed by a professional crew in as little as 2-3 days.

Standard 30 x 40 Steel Building Kit Package
Custom 30x40 Building with lean to
Made in USA
Solid Steel
30 Yr Warranty
Custom Engineered

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Why Choose a 30x40 Steel Building?

Versatility. Prefab building kits can easily be configured for virtually any application, from simple garages to custom modern family homes.

Durability. Rigid frame buildings are manufactured from solid steel framing and engineered to meet your local wind, snow, and seismic activity codes.

Affordability. You save on a 30 x 40 steel building compared to other methods of construction due to reduced material waste and reduced construction costs; for price/cost details, see our Steel building prices page.

A Solid Investment. Red iron buildings are permanent structures that are built to last, are warranted for up to 30 years, and add value to your property. They also require virtually no maintenance (no re-painting, replacing rotten boards, etc.)

A 30x40 metal framed building is a secure & affordable construction option that will stand the test of time in any geographical location.

  • Fast build time to occupancy
  • Economical building solution
  • DIY friendly construction
  • Custom-made to your specs
  • Near-zero maintenance
  • Easily expanded for future growth
  • Cost effective compared to wood
  • Adds value to your property

Features of a 30x40 Kit

All 30x40 building kits come fully equipped with all the necessary components for a basic structure - including primary and secondary framing, wall and roof metal panels, plus all fasteners and sealants. You then customize the base model by adjusting the roof profile and pitch and adding doors, windows, ventilation, etc., to suit your intended application and location best. Detailed below are some of the main kit features and specs.

  • Features

    Primary kit features:

    American-made, I-Beam steel framing, custom-engineered in factories across North America.

    • Customizable to suit any application
    • Designed to meet your local building codes
    • Certified to 160 mph wind & 110 (psf) snow load
    • Precision engineering for a weathertight structure
    • Red-oxide primer baked onto all components
    • Low maintenance, with 30+ year warranties
    • 100% usable, column-free space
    • Easily expanded for future growth *
    • Fast construction times
    • DIY friendly

    * if future expansion is a possible requirement, be sure to specify 'expandable end walls' when placing your order.

    I-Beam frame for a 30x40 steel building
    'I-Beam' frame for a 30x40 steel building kit
  • What's included

    All 30x40 building packages include:

    • 1:12 roof pitch (2:12-6:12 available)
    • Tapered steel I-Beams (primary framing)
    • All roof purlins & wall girts (secondary framing)
    • Two framed door openings (add extra if required)
    • Engineer stamped erection & anchor bolt plans
    • Pre-painted 26-gauge metal roof & wall panels *
    • All nuts, bolts, clips and fasteners
    • Detailed construction manual
    • Pre-drilled, numbered parts
    • Complete trim package
    • Sealants & flashing
    • Structural warranty (30-50 yrs)*
    • Paint warranty (30-40yrs)*

    *Vary by supplier

    Base kit building package
    Base kit package
  • Specifications

    30x40 building specs:

    • Wind load: 70-160 mph
    • Ground snow load: 10-110 (psf)
    • Available roof pitches: 1/2, 1, 2, 3, 4, 5 and 6:12
    • Roof styles: Gable, single slope, lean-to (LT)
    • Standard bay spacing: 20', 25' and 30'
    • Standard widths: 30' to 200' (clear span)
    • Standard heights: 10' to 40' (eave height)
    • Primary frame: I-beams (min.yield 42k psi) *
    • Second frame: purlins/girts (min.yield 55k psi) *
    • Wall & roof panels: 24 or 26 gauge metal panels

    * vary by supplier

    CAD Engineering plans
    Engineering plans for a 30 by 40 metal building
    BuildingsGuide ©
  • Exclusions

    Items not Included:

    • Delivery
    • Foundation
    • Construction
    • Insulation
    • Additional doors and windows
    • Gutters and downspouts
    • Interior finishing

    Pouring a 30x40 concrete slab foundation

The Construction Process

Red iron building - build process

How do you build a 30x40 metal building?

With a 30x40 building kit, you get all the necessary components to construct a precision-engineered, commercial-grade structure in as little as 3-4 days. You have the choice to DIY erect the structure or hire a local crew to undertake the construction. This section provides an overview of the planning, design, and construction process with links to articles for more in-depth coverage.

  • Step 1: Planning

    Planning a 30x40 building construction project.

    When considering a pre-engineered building for your home, business, or farm, you must be aware of all aspects of the construction process. From planning to execution, we'll guide you through everything you need to know to make your project successful.

    Determine Requirements

    What will you use your new structure for, and what are your storage requirements? The first step is to take a complete inventory of what will be stored in the new structure and ensure it will fit in the 1,200 sq ft.

    Decide on a Budget

    Take the time to budget for all the components of your build. This will include:

    • The 30x40 kit.
    • Additional accessories (doors, windows, skylights, etc.).
    • A 4" or 6" foundation
    • Permit fees
    • Erection cost
    • Insulation (if required).
    • Interior finishing (if required).

    Typical Installed Costs:

    • A basic 30x40 building with no interior finishing will cost $20-$50 per square foot, and
    • a 30x40 metal home with a full interior build-out can cost $100+ per square foot.

    Decide on a Height

    The intended end-use will govern the eave height of your structure. The building height is measured at the eave, and a two-foot clearance must be between the top of the doors and the eave.

    Some typical heights include:

    • Garages/shops - 10’ to 18’.
    • Barns - 12’ to 22’.
    • Single-story homes - 10’ to 14’.
    • Two-story homes - 18’ to 26’

    Please note: 30 x 40 metal frame buildings are limited to a height of 30 feet.

    Decide on the Number of Framed Openings

    The standard 30x40 kit package typically includes one framed opening for a walk door and one for a typical overhead door. You will need to decide how many more framed openings you need and how big each one needs to be. Remember that each of these will add to the cost of your building because each framed opening requires additional steel.

    Also, note that with a 30 x 40 metal building, the center column will typically be placed halfway down the building at 20 feet, giving you two 20-foot wide bays.

    Apply for Financing (if required)

    Several options are available for financing a new building; see the planning page at the end of this section for more details). If financing is required, identify suitable lenders at this stage. You cannot make the loan application until you have finalized all your building details and are at the pre-construction stage.

    Apply for Permits (if required)

    You will almost always need a building permit, but some rural and farm properties are exempt. Once you have chosen a suitable building site for your new structure, check with your city or county building department. Note that you won't be able to apply for construction and foundation permits until your chosen kit supplier has received your order and provided you with the relevant engineering drawings.

    Our suppliers ensure that your structure is engineered to meet your local codes for wind, snow, and seismic conditions.

    See our build process page for more details on planning a construction project, or read this great post on GarageJournal.


    TIP: One of the top pieces of feedback we hear from customers is 'I wish I'd added more space.' Before you order your new building, you may also want to consider these other similar-sized building kits.

    Add an additional 300 square feet by opting for a  30x50 metal building for $6,000, or double your floorspace to 2,400 square feet with a 40x60 metal building for an additional $19,000 investment.



  • Step 2: Design

    Design considerations.

    The level of design required for your 30x40 building will largely depend on what you intend to use the structure for. Below we briefly cover some of the main design aspects you will need to consider when customizing and configuring your new structure.

    Decide on a Roof Style & Pitch

    The intended end use of your 30x40 building will largely dictate the roof profile. For example:

    • Metal homes can have a gable (traditional), single-slope (modern) monitor, or even a gambrel roof (farm or barndominium), depending on the style you are looking to achieve.
    • Garages and shops will have either a gable or single-slope roof.
    • Barns will typically have a gable, monitor, or gambrel roof style.

    Available Roof Pitches:

    • Gable - 1:12 to 4:12 (steeper pitches require special engineering).
    • Single slope (shed roof) - 1:12 or 2:12.
    • Gambrel (Dutch barn) - Upper roof 2:12-3:12 and lower roof 5:12-6:12
    • Monitor - (American barn) - Upper roof: 4:12 - 6:12land lower roof: 3:12 - 5:12

    This being said, any roof profile and pitch can be applied to your custom 30x40 steel building.

    Choose a Floor Plan (if required)

    If your new structure is going to be used as a home, shop house, horse barn, or dog boarding kennel, you will need to decide on a floor plan that best suits your needs and maximizes floor space. To ensure you have sufficient space:

    Step 1: Research available online floor plans and shortlist the ones you think will work best. We also have a selection of sample floor plans to get you started. You can also create basic floor plans with our floor plan maker tool.

    Step-2: Take a complete inventory of what will be stored in your new structure. Take into account your current and possible future requirements.

    Step-3: To get a sense of what will work for your specific setup, plan your layout on graph paper (using a scale of one square = 1 foot) and place/arrange scaled cutouts of your inventory, livestock, and equipment on the floor plan.

    No need to hire an architect. Our suppliers will advise on design options to ensure you get the building you want in terms of functionality and aesthetics.

    Choose Custom Options

    A standard building package is sufficient for most customers, but various customization choices enable YOU to customize and configure the structure to meet YOUR needs. Popular custom options include:

    Color options: Mix and match over 20 colors for siding, roofing, and wainscot to get your desired look. See our colors page (follow the link to our design center at the bottom of this section) for sample color schemes and a color visualizer.

    Door options: Choose from sectional, roll-up overhead, sliding, or bi-fold doors, and pick sizes, styles, and colors that work for your setup.

    Siding options: All kits come standard with pre-painted, 26-gauge PBR metal roofing and siding panels. Alternatively, you can add vinyl, Hardie board, stucco, or faux brick panels.

    Structural options: Customize the exterior of your building by adding any number of structural customizations, including roof overhangs, door canopies, or a lean-to.

    See our design center for additional details on configuring and customizing a building.

  • Step 3: Ordering

    Get competing quotes for a building kit.

    Now that you have an idea of the design and style of your building, let us help you get started. Tell us a little about your project, and we'll match you with FOUR vetted suppliers who will provide competing quotes for your 30x40 kit package. Apply for quotes here.

    Once you have confirmed that you are happy with the design, a deposit (20-30%) is required before the factory can manufacture your custom building. A set of construction and foundation plans stamped by an engineer registered in your state will then be sent to you (usually in 2-3 weeks).

    Most vendors offer a full set of plans, but some charge extra for foundation plans. Before you submit your order, be sure to confirm this with the supplier.

    With all the necessary designs in hand, you can now request estimates from a local steel building erection crew (or a general contractor) for the construction of your 30 x 40 metal building.

    You will also be able to:

    • Approach your local building department and begin the permitting process, and
    • talk to lenders (if financing is required).

  • Step 4: Pre-Construction

    Considerations before you erect a 30 x 40 building.

    The time between ordering your building and taking delivery will typically be around 6-8 weeks, giving you plenty of time to prep your job site. Here are the steps you will need to consider at this project stage.

    Site Preparation

    Before pouring the concrete foundation, you will need to prepare the site in readiness for construction. This will include clearing and grading the site. Next, locate and map out access routes for water, gas, and other utilities. It is also essential to verify that the site can support the weight of the structure by conducting a soil analysis and determining if excavation and adding road base (or similar) will be necessary.

    Run Utilities to the Job Site

    Before pouring the foundation, you will bring in plumbers and electricians to bring services to your job site.

    Plumbing professionals lay the pipes, which the foundation then covers, and the electrician will run a conduit for the power lines to run through the foundation.

    If you are using your well as your water supply, check that the current pump and pressure tank can handle the additional demand.

    Pour the Foundation

    When constructing a 30x40 steel building, a slab-on-grade foundation is typically used. This foundation provides a stable base for the structure by pouring a concrete slab directly on the graded site.

    Foundation and anchor bolt plans are not typically included in the price of the building, so it is essential to consult with a local, licensed structural engineer to develop a foundation plan that meets all code requirements.

    Unless you have extensive experience installing foundations, we recommend having the foundation poured by professionals. A 4" slab will work for most end uses, but a 6" foundation will be required if heavy machinery is stored or used in your building. Another thing to consider at this stage is in-floor heating, which can be easily added during installation. Lastly, make sure that utilities are also roughed in before the pour.

    A 4" slab foundation for a 30x40 metal building will cost $4-$8 per square foot

    For more, see our foundations page.

  • Step 5: Construction

    Constructing a 30x40 building.

    When it comes to erecting a steel frame building, you have three main options for construction, which we cover below. Follow the link at the end of this section for additional details on the construction process.

    Prep for Delivery

    Kit packages are typically ready for delivery 4-16 weeks after an order is placed. Before starting construction, be sure to have lifting equipment on hand (e.g., a backhoe or forklift) and a place to store the framing, siding, and framing packages at your job site. The final balance of payment is typically due when the kit package is delivered.

    Three Options for Construction

    DIY Build: You take on the entire project, including pouring the foundation, erecting the structure, and finishing the interior. Steel-framed kits are designed with the DIY enthusiast in mind and come with numbered parts and complete instructions. With some construction experience and plenty of planning, a DIY build can save you 20-30% on the total project cost.

    As the foundation is a critical part of the build, we strongly recommend that you enlist a professional crew for this build stage.

    Self Build: With this option, you act as the GC for the project. You will be responsible for hiring and managing the erection crew, the foundation team, and any other subcontractors. You will also need to pull all the required permits. This option will save you the GC fees of 10-20%.

    General Contractor Build: You hire a GC to arrange and manage the erection crew and the subcontractors. This is the most costly option, but a good GC brings a wealth of experience to the project and can provide ideas you may not have thought of. This route is also by far the fastest option and one you should consider if you require a short occupancy time.

    A GC can also speed up the build time by getting permit approvals quicker due to their knowledge of the process and often due to their existing relationships with the building department and the local inspectors. GCs charge 10-20% of the project cost.

    For more details, see our page on metal building construction.

  • Step 6: Finishing

    Finishing the interior of a 30x40 building.

    Your intended use for the building and local climatic conditions will dictate the required interior finishing level.

    Wiring Plumbing & Finishing

    You only buy the building shell when you buy a kit from one of our suppliers. This includes all steel framing, metal roofing, and siding panels. In addition, you will need to hire local subcontractors to handle the wiring, lighting, heating, plumbing, flooring, and any internal framing that needs to be done.

    Add the Insulation

    Insulation is a worthwhile investment that can save you money on energy costs year-round. It helps keep your building cooler in the summer and warmer in the winter, prevents condensation, and provides soundproofing. Fiberglass blanket and spray foam insulation are the most popular options for energy efficiency. You can purchase these materials from your kit supplier or source them locally.

    For more, see our insulation page.

    Interior Framing

    Again, this will depend on your intended use for the building. But if interior rooms or a second level are required, you must hire a local framing company for this project stage.

    Most metal-framed buildings are single wide-open spaces. Optionally, the structure can be split into multiple sections to accommodate an office, a bathroom, a storage area, or a mezzanine loft level.

    Walkthrough and Final Inspection

    To ensure that your project is completed correctly and per local building codes, it is essential to have formal inspections carried out at various stages throughout construction. A final inspection will be required at completion to complete your permit process. Once you have passed your final inspection, you will be provided with a certificate of occupancy by the building inspector.

How much does a 30x40 metal building cost?

The average cost of a 30x40 building is $28,800 to $39,600, installed. This includes the building kit package at $15-$22/sq ft, the slab foundation at $4-$8/sq ft, and the building construction at $5-$10 per square foot. If required, doors, windows, and insulation should also be budgeted for. For an accurate cost based on your specifications and location, apply for competing quotes from four suppliers.

ItemSquare Foot Cost
Building kit (shell)$15-$25
Slab Foundation$4-$8
Interior Finishing$10-$100+

Common Questions

  • What roof pitches are available for 30x40 steel buildings?

    All 30 by 40 bolt-up kits come with a standard 2:12 roof pitch, although pitches ranging from a shallow 1:12 pitch to a steeper 4:12 pitch are available as an option. Some of our suppliers can provide custom roof pitches of 5:12 and 6:12.

  • How much does a 30x40 metal building with slab cost?

    On average, a 30x40 concrete lab will cost $7,200. Typically, a concrete slab will cost between $4 and $8 per square foot (based on a nationwide average) for both materials and labor. The final price will depend largely on your building location, as costs vary from coast to coast.

  • How many yards of concrete do you need for a 30x40 slab?

    The amount of concrete you need for a 30x40 slab depends on the thickness of the slab. For a standard 4-inch thick concrete slab, you will need 14.81 cubic yards of concrete; for a 6-inch thick slab, 22.22 cubic yards will be required.

    Here is the formula to calculate the amount of concrete you will need:

    Concrete needed = (length x width x thickness) / 27

    For example, to calculate the amount of concrete needed for a 30x40x4-inch slab, you would use the following formula:

    Concrete needed = (30 x 40 x 4) / 27 = 12 cubic yards

    It is always best to order a little extra concrete than you think you will need to allow for spillage etc.

  • What is a 30x40 red iron building?

    Red Iron is a term used to describe a pre-engineered steel building. Although the structures are not made from iron, they have a red finish due to the red oxide paint applied to the framing during the manufacturing process to prevent corrosion.

  • Whats the difference between a 30x40 and a 40x30 building?

    All building measurements are listed in the following order W x L x H. The main difference between a 30x40 and a 40x30 building is the orientation of the width and length.

    For a 30x40 building, the width is 30 feet, and the length is 40 feet. It is quite common to mistake the dimensions and for customers to request a 40x30 building by mistake.

    Dimensions can also be expressed as 30 feet by 40 feet; or 40 feet by 30 feet.

  • How many square feet is a 30x40 building?

    A 30x40 building has a total floor area of 1,200 square feet (sq ft). The calculation to determine this is done by multiplying the width (30 feet) by the length (40 feet) of the structure.

    For example, a 30x40 metal building would have a floor area of 1,200 square feet. This is the same as a 25x50 building, a 20x60 building, or a 15x80 building.

    1,200 square feet is a good size for a variety of uses, including an oversized garage, workshop, small warehouse, or even a small two-bedroom home. It is important to consider the needs of your specific project when choosing the size of your building.

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