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Complete Guide to Building a Portable Generator Shed

Key Points

  • Learn how to properly store your portable generator and protect it from inclement weather during operation to increase longevity
  • Key factors you must know before building a portable generator shed


I relied heavily on my Briggs and Stratton Storm 5500 portable generator during the aftermath of Hurricane Sandy (it took 18 days to restore utility power).

Understandably, everything was chaotic, so I started out with a simple piece of plywood as a roof to protect my generator from rain and sun.  Then, after things calmed down, I planned on building a more permanent protection.

Well, life got in the way, so I ended up leaving this setup for over two and a half years.

Although the plywood roof protected my generator during light rain, all four sides were open to rain and snow.

So, my portable generator ended up being exposed to constant precipitation (spring), UV from the blazing sun (summer), pests taking up residence (fall), and snow (winter).

The Storm Responder wore out quickly in these conditions (for example,  rubber parts became brittle, the generator was hard to start, etc.)

To prevent this from happening again, when I purchased a new Caterpillar RP7500E generator, I looked around to see what options were available on the market.

One task I hated the most during two and a half years of operating a generator in the exposed environment was refueling my generator during pouring rain or heavy snow.  So my future generator shed must provide shelter for the generator and the operator (me).

After not finding any enclosure that fit my budget and taste, I built a large generator shed to store both generators and operate a generator inside it.

In this post, I will show you how to decide what type of structure is right for your portable generator, where and how to built it, what materials to use, and how to maintain it.

I will show you clear step-by-step photos as it is built, along with a detailed instructions.

Leveraging my prior experience designing and building my storage sheds, it took about a week to design and plan, buy materials, build, and put my shed into service.

Do You Really Need a Generator Shed?

When I made two storage sheds a few years ago, I designed them to store a variety of items, such as tools, equipment, or household goods.

In contrast, I wanted a generator shed that can store and operate my generators.

If you are considering powering your home (via generator connected to your main load center), you should definitely consider a generator shed.

Storage shed vs Generator shed

There are a few key differences between storage versus a generator shed:

  • Size – In most cases, a storage shed will be larger than a generator shed to accommodate the size of the lawnmowers, ladders, and other equipment
  • Ventilation – A generator shed will typically require more extensive ventilation than a storage shed to handle increased fresh air supply demand and handle engine exhaust fumes
  • Electrical requirements – A generator shed will need to accommodate electrical outlets or cords to allow the generator to power other devices or a home
  • Noise reduction – A generator shed will need soundproofing to reduce the noise created by a generator

It is perfectly acceptable to use a storage shed to store generators but storage sheds should not be used to house an operating generator due to its lacking safety features.

Can a generator be left outside year-round?

Before diving into this question, learn about different generators to understand their purpose.

In a residential setting, three types of generators are commonly used:

  • Standby generators are made to operate outside in harsh climates 24×7, so it is perfectly acceptable to be left outside year-round with metal cladding
  • Smaller inverters and solar generators come with sensitive electronic components so they should not be stored outside. Some inverter generators can handle inclement weather when operating, but your inverter generator will last longer if you provide shelter during operation.
  • Most portable generator manufacturers state that generators can be left outside year-round, but UV and moisture from rain and snow will negatively impact the life of various components. For example, a rubber hose is highly susceptible to damage from UV.

If you purchase a portable generator, you should find a proper storage space that can also be used to provide shelter during operation. This protection from extreme weather conditions, such as heavy rain, snow, and extreme cold and temperature will make your generate last for a long time.

If you are Unable to Build a Portable Generator Shed

When Hurricane Sandy barreled through the Northeast, I had to run my generator 18 hours a day, so I made a temporary plywood roof to protect my precious generator.

Although this setup was okay for a short duration, I had to contend with several issues:

  • Fuel contamination: The size and height of my plywood roof were respectively small and low, and the generator had to be removed from its shelter during oil changes and refueling which meant I had to contend with water entering the fuel tank if it was raining or snowing (water is harmful to a gasoline engine)
  • Premature wear: The roof prevented direct sunlight from reaching my generator around noon, but at other times, it exposed the sides to UV, which meant the rubber parts got brittle. The generator exposed to all four sides from moisture (i.e., during heavy rain or snow) is not optimal either.
  • Noise: A running generator at full load produces 80 to 90 decibels, so it is pretty loud even with windows closed

When s**t hits the fan and you need to get your generator going where you cannot provide any sheltering protection, there are two options that you can consider:

  • Protect your generator using a weatherproof cover like this Porch Shield Waterproof Universal Generator Cover (26 x 20 x 20 inch) which fits securely and is made of materials that can withstand the elements. Please remember that even a breathable cover will trap moisture. To prevent you generator from prematurely rusting, you should make a habit of removing the weatherproof cover and letting your generator dry out in a cool shade (not in the direct sun)
  • Consider protecting your running generator from the weather with a tent cover like IGAN’s Ultra Heavy Duty Tarpaulin Rain Shelter Enclosure.
  • Just keep mind that you need to locate your generator on a higher ground to avoid water on the ground.

Anatomy of a Generator Shed

The diagram below shows the standard building components and how they all fit together.

  • A – gravel base
  • B – floor frame
  • C – floor
  • D – studs
  • E – header
  • F – rafters
  • G – T11 siding
  • H – fascia board
  • I – drip edge

Feature Wish List

Building a generator shed means I have the opportunity to customize it anyway I want (within budget).

So, I came up with these features and items I want to include in my shed build:


  • Shed materials – Use wood as the primary building material because it is easier to cut and modify wood than metal or plastic; wood also does not warp as easy as plastic when exposed to sun (better durability); wood also does retain heat like metal (better heat control)
  • Heat management – heat is the enemy when it comes to engine and electronic component durability; my generator shed will have two fresh air supply routes (active fan; passive under roof eve) and one exhaust pipe (with active fan) to dispel heat and exhaust fumes; during bitter cold environment, the exhaust pipe insulation will be removed to provide additional heat to the generator shed
  • Noise control – portable generators are definitely too loud; if not careful, operating a generator inside an enclosure can amplify that sound (like a megaphone); you buy an exhaust mufflers specifically made for generators (see or make one yourself; either case, you need to make sure to minimize the exhaust backpressure does not increase (will reduce generator performance); walls will be insulated and covered with concrete wallboards (common trade name is “Durock”) to deaden the sound.  The floor will be covered a two layer of high-density rubber (think of gym mats) to further separate the generator vibration from the shed structure
  • Water / moisture management – next to heat, extra moisture during storage will increase rust on your portable generator; place the shed on higher ground to avoid water from penetrating the shed; Elevate the shed off the ground further ensure that there is a plenty of air movement between the bottom of the shed and the ground
  • Roof – slanted roofing style (commonly found in lean-to tool sheds) is easy to build; unlike lean-to sheds, the higher end of the slanted roof will provide height and cover during refueling and maintenance
  • Doors – double-wide door for easy access to perform maintenance work without getting wet

Accessory Items You May Want to Consider Buying

  • Roof light – Duraflo 5950C Shedlight Roofvent Transluscent Shedlight Roof Vent, Translucent
  • Shed lighting – for night refueling operation
  • Mirrors – to see the fuel gauge as it is being refilled
  • Refueling hookup hose – allow refueling when engine is too hot to touch
  • S-shape exhaust vent to reduce sound
  • L-shape fresh air intake – to reduce sound escaping
  • Digital thermostat with wi-fi – temperature monitoring

Buy or Build

One of the most popular way of storing portable generators was to re-purpose a plastic tool storage shed. Plastic sheds are relatively inexpensive and quick to assemble and I saw a ton of people going with this choice (you can read my Lifetime Horizontal Shed review here).

I was in a bit of a pickle because I had two 2 portable generators sitting in my garage. With winter approaching, I definitely want my cars back in the garage so I need to come up with a storage solution.

After going back and forth between a small enclosure vs. a generator shed, I decided to go with the shed option primarily.

You can read my post, Should You Buy or Build a Shed, to see if you should buy or build your portable generator shed.

Project Plan Overview

For every build project, I like to briefly outline what needs to be done in order for me to stay organized. Here is my action plan to build a portable generator shed:

Phase 1

  • Choose a location for the shed that is close to your home, so that it is easily accessible for refueling and maintenance. However, the location must be far enough away from home (doors, windows) to minimize noise and exhaust fumes
  • Obtain any necessary permits or approvals from your local government or homeowner’s association to avoid headaches down the road

Phase 2

  • Design the shed, taking into consideration such factors such as the size of your generator, ventilation, and electrical requirements
  • Purchase materials and gather tools. You will need gravel, concrete blocks, lumber, roofing materials, doors hinges, etc. A detailed list of the list is provided in the Materials section
  • Build the shed according to your design. Shed building does take a bit of patience, especially if you have never worked with tools but it is doable
  • Install the generator, making sure to follow all manufacturer safety guidelines and have the installation inspected by a code enforcement official
  • Test the generator to ensure it is working properly

Leveraging my prior experience designing and building my own storage sheds, it took about a 2 weeks to design, get the necessary permit(s), procure materials, build, and put my shed into service.

Picking the Right Site

When choosing a site for a generator shed, you should consider the following factors:

  • Site Accessibility
  • Distance from your home
  • Zoning Requirement
  • Neighbors/HOA
  • Topography

Site Accessibility

The generator shed should be easily accessible so that you can perform maintenance or refueling with minimal amount of effort.

When picking a right site for your generator shed, you should consider the following:

  • Path to the shed – is there a clear path to the generator shed?  How easy would it be to remove your portable generator for service?  A portable generator usually weighs around 250 pounds so they are not easy to maneuver
  • Obstacles – do you have any obstructions like fences, bushes or other structures that may get in the way?
  • Lighting – Can you safely get to your shed when dark?
  • Doors – are the doors wide enough to give you complete access to your generator?

Distance from your home

There is no one-size-fits-all answer to how far the generator shed should be located from your home because the appropriate distance will depend on the size of the generator, types of transmission wires, and the purpose for which it will be used.

One overarching fact you need to consider is the drop in Electric transmission efficiency as distance is increased

Electric transmission efficiency refers to the percentage of the electrical energy that is transmitted from the source to the load.

As the distance between the source and the load increases, the transmission efficiency typically decreases.  This is due to three primary factors:

  • Resistance: Electrical energy is transmitted through wires, and all wires have some level of resistance. As the distance increases, the resistance of the wire also increases, which results in a loss of electrical energy
  • Voltage drop: As electrical energy is transmitted through a wire, the voltage of the energy decreases due to the resistance of the wire. This is known as voltage drop. The longer the distance, the greater the voltage drop, which can reduce the transmission efficiency
  • Power loss: In addition to resistance and voltage drop, other factors such as skin effect and proximity effect can also cause power loss as the distance increases

Therefore, it is generally more efficient to transmit electrical energy over shorter distances. However, there are ways to mitigate these losses, such as using higher-quality wire or boosting the voltage at the source.

In general, a distance of 10-20 feet from the generator to the shed is a good starting point. However, it is always a good idea to consult with a professional or refer to the manufacturer’s recommendations for specific guidance on the appropriate distance for your generator.

Zoning department

In certain jurisdictions, your local zoning ordinances may specify what you can and cannot do on your property.  They may also specify the height of outdoor structures and the setback requirements (minimum distance required from your generator shed to your nearest property line).

If you are planning to build a generator shed on your property, you will need to check with your local zoning department to determine if a generator shed is allowed in your zone and what regulations apply to its construction.

If You live in a Hurricane-prone area
If you live in one of the gulf states like Florida, Texas and Louisiana, it’s a fact of life that you get frequent storms. These states have far stricter building codes to ensure that your building materials do not become projectiles during a storm.  Please check with your local code enforcement officials to find out what additional materials need to be installed to stay complaint (i.e. must use hurricane straps, etc.).

The zoning department can provide you with information about the zoning regulations that apply to your property and help you determine whether your proposed use is allowed.

Neighbors / HOA

When planning to build a generator shed on your property, it is a good idea to consider how it may impact your neighbors and any homeowner’s association (HOA):

  • Noise: Generators can be noisy, especially when they are running, an generate toxic exhaust gas. If your generator shed is located close to your neighbors’ homes, they will be negatively impacted by the noise/exhaust. Be sure to consider the placement of the shed and the generator to minimize the impact on your neighbors
  • Aesthetics: Your neighbors and HOA may have concerns about the size and appearance of the generator shed. Make sure to choose a design and color that will blend in with your neighborhood and consider any HOA guidelines for exterior structures
  • Maintenance: Keep the area around the generator shed clean and well-maintained. This will help reduce the impact on your neighbors and maintain the appearance of your property
  • Communication: It is always a good idea to communicate with your neighbors and HOA about your plans for a generator shed. This can help address any concerns they may have and ensure that you are able to move forward with your project smoothly.


Topography describes shape, soil type, and features of the land surface like rock cropping, trees and vegetation.

When selecting a site for a generator shed, the following factors should be reviewed:

  • Level ground – generator shed should be constructed on a level ground.  Generators vibrate quite a bit when running and sitting on an uneven surface will cause them to roll around and possibly tip over.  Location that is too steep will make it more difficult to construct a generator shed, and negatively impact ingress/egress during refueling and maintenance
  • Terrain – Low-lying areas tend to flooding, especially if the soil consists of dense material like clay. A generator will be of no use to you if it gets flooded.  Besides, operating an electricity generating equipment while standing on a pool of water is can kill you
  • Drainage – The type of soil on the site can affect the stability and drainage of the generator shed. Clay You want a loam or rocky soil for maximum drainage and stability
  • Vegetation – A generator shed surrounded by overgrown vegetation will prevent proper air flow.  Either pick a location with minimal amount of vegetation or trim them down

Meeting with Your Local Code Enforcement Officials

It would be wise to visit your local code enforcement, even if you don’t think you will need a permit to build your generator enclosure/shed.

Depending on your local township, you may have to visit the building, electrical, or zoning departments.

Building Department

Building department oversees building codes, rules and regulations created by your local jurisdiction that governs the design and construction of a building.

Ask them to provide you with a specific list of building codes you must follow when building a portable generator shed.  Some of the questions you may want to ask are:

  • What is the maximum size of a generator shed as a temporary structure? The total square footage will determine if a permit is required. To get the total square footage, multiply the length by the width. For example, if your generator shed is 6 feet by 3 feet, the total square footage is 18 sq. ft
  • What is the height of your generator shed?
  • Is there a requirement for the foundation?  Foundation requirements vary depending on the size of your shed.  For example, a shed that is less than 100 sq. feet can be sitting on skids (considered to be a temporary structure).  A shed that is greater than 100 sq. feet may be required to be attached to a poured concrete foundation (considered to be a permanent structure). Keep in mind that permanent structure may increase your annual property tax
  • What materials are used to build a generator?  Your town may have specific rules and restrictions on using certain types of shed materials due to their potential fire hazards

Zoning Department

A zoning department is a responsible for creating and regulating the use and development of residential and commercial property.

Your local zoning ordinance may specify if a generator shed will be allowed or not for your property so ask these questions?

  • Number of outdoor structures – l number shed allowed?  Some jurisdictions stipulate the maximum number of outdoor structures.  However, a generator shed maybe small enough to be counted
  • Where will you place your generator enclosure?  Setback requirements will dictate the minimum required distance between the shed to the nearest property line
  • Bring a copy of your property survey.  A survey should include property lines, easements, buried oil tanks, and any septic tank/leeching fields (if any).  A survey and shed location are needed as each town has its own minimum setback (distance away from a property line) requirements

Electrical Department

If you plan on powering your home via the main load center, you will need to obtain a permit to do so.

Bring the following information before speaking to an electrical code inspector:

  • Main load center – brand and model
  • Generator interlock kit – brand and model
  • Generator interlock circuit breaker – brand and model
  • Genset patch cord specs – usually NEMA connector from your generator to the NEMA inlet port located on the side of your house
  • Service cable – connected from your NEMA inlet port to your main load center
Tips on Organizing Paperwork
Permit applications and supporting document can get pretty messy. I also have a habit of losing paper so I like to use a fifty-cent marble notebook to keep track of a list of materials, vendor phone numbers, meeting notes, etc. and a simple vinyl folder to keep all submitted paperwork in one place. For example, when I meet with various code enforcement officials, I grab their business cards and staple them in my notebook and also make detailed notes of the conversation. 

Estimated Cost (budget)

The cost of a small generator shed can range from cheap (plastic frame with PVC sheets) to very expensive (highly customized with top of the line materials).

Another big factor is the upgraded materials and extra hardware you need to build a generator shed in a weather-intense area (like Florida) and your taste.

My taste is pretty basic but I do like to build stuff that are sturdy so my overall cost tends to be slightly higher than the average cost.

Here is my estimated budget for the generator shed project:

  • Framing (wall and ceiling): $80
  • Framing (foundation): $100
  • Sheathing: $50
  • Decking (roof and floor): $80
  • Door and hardware (screws, nails): $60
  • Shingles and roofing accessories: $150
  • Windows: N/A

Please keep in mind that the total cost ($250) does not include any tools you may need.

I will share with you the final cost at the end of my build out in my next post.


Building a portable generator shed does not have to be complicated, but you should read the entire post to understand the important factors to CYA (cover your a**).

I was going to include the building steps but this post got too long so head on over to “How to Build a Portable Generator Shed” article to read my step-by-step instructions.

If you found this post to be helpful (or not), would you please take a minute or two to leave a comment below?