A 30×40 metal building kit encloses 1,200 square feet, a footprint 30 feet wide and 40 feet deep. That is a true three-car garage with a full workshop behind it, or a clear-span shop wide enough for a lift, a work truck, and room to move around both. Thirty feet of width clears three bays with no center post, and the 40-foot depth turns the box into a serious working building.
This guide sits under the metal building sizes pillar, and it covers one footprint in depth: what fits inside a 30×40, the uses it suits, the frame and options you will see on a quote, the clear heights you can order, and an illustrative 2026 price range. To see this size against every other footprint side by side, the metal building size chart puts it in context.
1,200 square feet
What a 30×40 metal building kit covers
Thirty feet wide by forty feet deep gives you 1,200 square feet of enclosed floor. The width is the headline: 30 feet parks three vehicles across, or two vehicles with a full work bay alongside, and a red iron frame holds that span open with no interior post. The 40-foot depth is what makes this size a workshop and not just a garage, adding a back third for a bench, a parts room, or a second piece of equipment.
Think of it as the size where a garage becomes a shop. Three cars take up roughly the front 20 feet of depth, which leaves about 20 feet of clear floor across the back for a work area, storage, or a mezzanine overhead. That reach is why a 30×40 suits owners who outgrew a two-car building and tradespeople who run a business from one roof. If you need length for an RV or a longer line of equipment, step up to the 30×50.
What fits
What fits inside a 30×40 building
Three vehicles, or two vehicles and a real shop, or one large rig with room to spare. The table below shows how a 30×40 handles the loads people most often park in this size, and where the footprint starts to set the limit.
| What you want to store | How a 30×40 handles it |
|---|---|
| Three cars side by side | Fits all three across the width with door-opening room between them |
| Two vehicles plus a shop | Cars up front, a full bench, tool wall, and parts room across the back |
| Work truck and trailer | Parks a long truck and a trailer in line with depth left over |
| RV or camper | A length up to roughly 38 feet ‹confirm› fits the floor, if the door clears the roof |
| Boat plus a daily driver | Boat on a trailer down one bay, a vehicle and gear in the others |
| Tractor and implements | A tractor, a mower, and attachments with a workbench under one roof |
What clears and what does not. A 30×40 is a three-lane building with full workshop depth.
Mind the door, not just the floor
A tall RV or a lifted truck can fit the floor plan and still hit the door header. The roll-up opening sets your real clearance, so order the door height around the tallest thing you park, not the average. The how to choose a size guide walks through measuring before you buy.
Common uses
Common uses for a 30×40 footprint
The 1,200-square-foot footprint hits the sweet spot where a building stops being personal storage and starts earning its keep. These are the jobs it does best:
- Three-car or collector garage. Daily drivers plus a project car, with depth for a lift and a tool wall.
- Home workshop or trade shop. Woodworking, welding, fabrication, or a maker space with vehicle bays alongside. For layout ideas across sizes, see what people build.
- RV and toy storage. A full-size motorhome or several smaller toys off the weather and out of the driveway.
- Small business or contractor base. Work trucks, materials, a parts counter, and a small office partitioned in one corner.
- Barn, studio, or finished space. Insulate and line the interior and the 40-foot depth gives you a genuine room with space to grow.
If you want covered space more than an enclosed room, the same footprint works as an open or partly enclosed cover for less money. Compare it against the squarer 30×30 and the longer 24×36 before you commit, since a few feet of width or depth changes what the building can hold and what it costs to heat.
Frame and options
The frame, doors, and clear height
At a 30-foot width most kits use a bolt-up red iron frame, because that span asks for the load rating and the clear floor a structural frame gives you. Frames are sold by wall thickness in gauge for the lighter members, where a lower number means thicker steel, but the primary frame on a building this wide is usually structural I-beam rather than tube. A red iron frame clears the floor of interior posts, which matters when you park three wide or run equipment across the bays.
Clear height is where buyers most often under-order. The eave height, the wall height at the side, sets how tall a door you can hang and how much headroom you keep inside. A 30×40 is commonly offered with side walls from about 10 to 16 feet ‹confirm›. Twelve feet suits a shop with a single lift; go to 14 feet or more if you want a tall RV door, a two-post lift with a truck on it, or a loft across the back.
On the options list you choose a roof style, the doors, and any openings. Two or three roll-up doors plus a walk-in door cover most three-bay builds. The roof comes as standard, A-frame, or vertical-rib, with the vertical roof shedding water and snow better for a small premium. Order the certified load rating for your county so the kit is stamped for local snow and wind, not just the base spec.
Order the size you will grow into, not the one that just fits today. A few feet of eave height or a third roll-up door costs far less now than a rebuild later.
Price
What a 30×40 metal building kit costs in 2026
As a 2026 illustration, a 30×40 steel shell kit runs roughly $15,000 to $35,000 ‹confirm› for the bare building. The spread is wide because frame type, eave height, roof style, door count, and the certified load rating each move the number. A basic enclosed shell with a low eave sits near the bottom; a fully certified red iron shop with a tall eave, three roll-up doors, and a vertical roof sits near the top ‹confirm›.
That figure is the kit alone. Budget separately for a concrete slab, delivery, and any insulation or interior finish, which can add several thousand dollars ‹confirm› on top of the shell at this footprint. For the full breakdown of what drives the total, see the metal building kit prices pillar.
Treat any single number with care: prices move with the steel market, your location, and the season. Get a written quote stamped for your address, confirm the frame type and the load rating, and check it against current ranges in the size chart before you sign.
FAQ
30×40 metal building kits: common questions
How many square feet is a 30×40 building?
A 30×40 building is 1,200 square feet, found by multiplying 30 feet of width by 40 feet of depth. That is the footprint of a three-car garage with a full workshop behind it, or a clear-span shop wide enough for a lift, a work truck, and room to move around both.
How many cars fit in a 30×40 garage?
Three vehicles fit across the 30-foot width with room to open the doors, and the 40-foot depth leaves space behind them for a fourth car, a lift, or a workshop. It is one of the smallest footprints that holds three cars and still works as a real shop.
How much does a 30×40 metal building cost?
As a 2026 illustration, the bare shell kit runs roughly $15,000 to $35,000 ‹confirm›, depending on frame type, eave height, doors, roof style, and the certified load rating. A slab, delivery, and insulation are extra. Always get a written quote stamped for your location before you compare prices.
How tall can a 30×40 building be?
Side wall, or eave, heights of about 10 to 16 feet ‹confirm› are common at this size. Twelve feet suits a shop with one lift; order 14 feet or taller if you want a tall RV door, a truck on a two-post lift, or a loft across the back. The eave height sets how tall a door you can hang.
Will an RV fit in a 30×40 building?
A motorhome up to roughly 38 feet ‹confirm› fits the floor length, but the roof height is the real limit. Tall Class A coaches need a 14-foot or taller eave and door, so confirm the clear door opening, not just the floor length, before you order.
Does a 30×40 kit use tube steel or red iron?
Most do use red iron. At a 30-foot width a bolt-up red iron frame gives you the clear span with no center post and the load rating a building this wide needs. Light-gauge tube is better suited to narrower carports and small garages than to a 30-foot span.
Related guides
Keep reading
Comparing this footprint against its neighbors and the hubs that put it in context:
- Metal building sizes: the complete guide (the parent pillar).
- 30×30 metal building kits and 30×50 metal building kits (the sizes on either side at the same width).
- 40×40 metal building kits (a wider footprint if 30 feet feels tight for the bays).
- Most popular metal building sizes (where the 30×40 ranks among buyers).
- How to choose a metal building size (measure before you buy).
- Metal building size chart (every footprint and its uses in one table).
