18x20 Metal Building Cost

A rough cost guide to 18 by 20 steel buildings

18x20 metal building cost

An 18 x 20 metal building has become the most common size for residential use. The 18-foot width of this building allows you to include both a standard garage door as well as a man door for easy access. The most common uses for this size of building are:

Let's Look at some pricing Considerations.

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Types of 18x20 Metal Buildings

There are three main types of metal buildings that are used for this size of structure. The first step in your pricing process will be to determine which type of building you want to choose as all of them have slightly different prices.

Rigid Frame Buildings

metal frame buildingsWhile a rigid frame building is an option for your 18 x 20 building, we don't typically recommend them for buildings of this size. The reason for this is that, unlike arch steel Quonsets, a rigid frame steel building will typically require professional construction assistance due to the weight of the Interior steel frame that is used.

You could of course have a rigid frame building in this size, but it's kind of Overkill as the span of this building does not require the heavy gauge steel framing this type of building comes with.

18x20 Light Frame Metal Buildings

A light frame steel building would be our second recommendation for this size of structure. This type of building is sometimes called a c-channel building. It also uses an internal frame with steel cladding on the outside, similar to a rigid frame, but the steel frame is a much lighter gauge and is often in a 'c' shape.

The main reason we recommend a Quonset over a light frame steel building is due to the longevity of the structure. The gauge of Steel used on Quonset walls would be heavier than you would see in a typical light frame steel building. This extends the life of your building and can help make it a better investment for your property.

18x20 Quonset Hut Buildings

quonset garage workshopA Quonset hut is a popular choice for this size of building. The main reason for this is that it's quite simple to build your own quonset and many residential customers want to handle construction to save on costs.

Quonset Huts are manufactured in a factory and ship to you typically on a couple of pallets. It is comprised of Steel panels that bolt together to create arches. These arches are then bolted together in a row to create the walls and roof of the building.

Quonsets come in a few different profiles. The thought of a semi-circular military building may first come to mind, but these days you can purchase Quonset in multiple shapes including more traditional looking ones with straight sidewalls and a peaked roof.

Price Considerations

Core Structure

It's more difficult than you may think to price an 18 by 20 metal building. The reason for this is that this size of building virtually always requires Municipal Building approval. When you need municipal building approval you need to ensure that the building is correctly engineered for your location. As a result, the cost of the building will vary from one location to another due to snow and wind loads.

In general, for this size of building you'd be looking at a cost per square foot of about $13. 18x20 is 360 square feet bringing you to a cost of $4,680 for the building itself. As your building size gets larger, the cost per square foot reduces so the cost here is relatively high.


Delivery costs will typically be included for larger metal buildings. At this size however you may find that you're paying an additional $500-1000 in shipping. This is not always the case though and you may be able to negotiate it in.


building slab foundationA concrete slab foundation will be your go-to here. Another option you may consider is a peripheral wall with a gravel floor. Typical foundation costs will be $4-6 due to the cost of concrete and labor. This means you'll be set back about $1,800 to have your foundation poured.


You can accessorize your steel building with a variety of different add-on. These include things such as:

  • Windows
  • Doors
  • Vents
  • Skylights
  • Custom colors for the exterior panels of your building

Construction Cost

While it's common for people to construct their own 18 by 20 buildings, you may choose to bring in a professional contractor. If you do that, then you should expect to pay between $5 and $8 per square foot. This price will vary significantly from one region to the next, however. You may find that many contractors are reluctant to take on such a small job.

Estimated 18x20 Metal Building Cost

Below is a breakdown of the different price components and what this building may end up costing you in the end.

Low Range High Range
Building Only Cost $3,600 $9,000
Per Sq. Ft. Building Only $10 $25
Foundation $2,160 $3,240
Doors & Windows $360 $1,440
Utilities $0 $360
Accessories $90 $900
DIY Finished Cost $6,210 $14,940
Per Sq. Ft. $17 $42
Labor Cost $2,160 $3,600
Turn-Key Cost $8,370 $18,540
Per Sq. Ft. $23 $52


The numbers above are very rough estimates so if you're looking to get an actual building price, you can do so here.

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