The Basics: Generator Concrete Pads

In order to keep generators working properly and up to code, it needs to sit up and away from mud and dirt, which can be achieved by planning and installing a concrete pad. A concrete pad is the best option for a stable and clean environment for your commercial generator system.

A concrete pad used as a foundation for your generator is created specifically for the shape, size, footprint, and weight of your generator.

An undersized pad can cause many problems, including:

  • Insufficient space to safely install your generator
  • Inadequate room for access and maintenance
  • Overloading of your pad (this could lead to cracking)
  • Legal and regulatory non-compliance issues
  • Possible fines or enforced generator shutdown

Planning Your Generator Concrete Pad

Once you have determined the type and size of the generator, then you want to move into the planning process. Be sure to take time and study the potential foundation layout for your concrete pad. Also, be sure to invest in ensuring you have a high-quality pad that is adapted to the size and position of your new commercial generator to be installed.

Concrete pad foundations must be expertly constructed in terms of thickness. Concrete pads are carefully calculated for the perfect thickness of concrete, so the generator pad does not crack. If the generator pad is too thin or too thick, there is a higher possibility of the generator pad cracking, which can result in not only damage to your generator, rendering the generator inoperable, but it can also result in legal & regulatory issues that can include fines and a shutdown of the generator from continued operations.

Concrete generator pads will more than likely require vibration insulators. These ensure vibrations created by your generator are not transmitted into your facility, where they can disrupt sensitive equipment and your employees. When designing the concrete foundation, precise calculations can help determine the vibration specifications of your generator and take into account for any vibration insulation requirements.


Placement of the generator is vital when it comes to mounted stationary generators. Unless you designate a space within the facility for the generator – known as a generator room, there are generally only two other options for placement. They will be installed either outside of the building on the facility premises or on the roof of the building.

If placed outside of the building within the facility’s premises, be sure to survey the installation area. If the ground is unstable or is prone to shifting (gravel beds, sand, etc), then you will need to look for another area to install the concrete pad. If the area is often wet and prone to flooding, it will not be a suitable location to install a stationary generator. While there are arguments that the concrete pad can help raise the generator higher, even in flood prone areas, floods can often exceed those heights dependent on geographical location and temperature climate.

When surveying the property for an appropriate location to install a generator, look for the higher possible ground with the most stable foundation. The area should also be level, with any downhill grades leading away from the installation site to prevent standing water from pooling up under your generator. Additionally, a quality enclosure will help weatherproof your generator from the elements and protect it from unnecessary wear & tear.

If the generator must be installed on the roof, then make sure that the structure is able to support the weight of the generator set and also consider the following:

  • Load Bearing Requirements: Be sure to factor in the total weight of the fuel tanks, batteries, radiators, generator concrete pads, any/all accessories, and be sure to add in the total weight of the generator together.
  • Accessibility: The generator should be easily accessible for technicians to perform routine tests, checks, maintenance, and testing, as well as any service work that must be conducted.
  • Security: Make sure the generator is installed away from access to the general public to prevent unauthorized access.
  • Fire Codes: Any and all applicable local fire codes, building, and zoning laws must be followed.

Generator Pad Construction
Concrete is the most commonly used material for a generator pad foundation. While there are some variations, such as timber construction wood framing filled with gravel, concrete provides the most stable base and higher durability. Gravel will shift over time and will need to be replenished or re-leveled from time to time or debris can get caught in the gravel.

As mentioned above, the total weight of the generator and all components must be carefully calculated in order to safely and properly construct the pad.

Calculate Generator Concrete Pad Weight:
Standard calculations for determining the weight of the concrete pad can be found by multiplying the number of cubic feet in its volume (length x width x height) by 150 pounds. After determining the weight of the concrete pad, be sure to confirm that the weight is within load bearing limits of the installation location.

Generator Concrete Pad Specifications:
The composition of the mounting pad should follow standard practice for required load bearings. The specification with 2500-3000 psi is for concrete reinforced with eight-gauge wire mesh of #6 reinforcing bars on 12” centers.

Generator Concrete Pad Mixture:
Recommended mixture by volume is given as 1:2:3 parts of cement, sand, and aggregate.

Conduit Entry:
When mounting the generator on the concrete pad, make sure necessary provisions are made to receive the electrical conduit. An area where the cables come through, called a “stub-up” must be optimally placed to the generator set’s load and control terminal connections.

Constructing a generator pad for your commercial generator is a process that requires precise and accurate calculations. There are many factors and considerations that must be calculated into the design and planning, before the actual installation process. While many will elect to attempt the installation on their own, it would be best to contract an experienced professional who specializes in generator foundations and concrete pad construction.

If you are looking for more information about concrete pads for generators, please feel free to reach out to us.

Give us a call or send us an email: 610-658-3242 or

The Woodstock Power Company Experience

We have industry experts that focus on commercial generator sets, with in-depth industry knowledge to help you choose the right generator that fits your needs.

We are industry leaders in buying and selling used generators to fit the needs of many businesses, including commercial, industrial, medical, agricultural, and university. This includes facilities like hospitals, better living centers, nursing home, airports, hotels, resorts, restaurants, retail centers, manufacturing, production, and more.

Our experts are ready to assist you from answering any questions you may have about power generator sets to helping you find the best selection in our inventory based on:

  • Peak & Average Power Requirements
  • Fuel Preference (Natural Gas or Diesel)
  • Portability & Stationary Power
  • Prime & Standby Generator Requirements
  • Available Space & Exhaust Restrictions

We carry only the most top rated new, used, and surplus power generator sets for sale, providing you with a great value generator that will fit your budget.

Our generators have been thoroughly inspected, serviced, and verified, which ensures that you will be buying a quality generator that you can depend on. If a generator is not up to par with industry standards, we make all necessary repairs or modifications, and fully test every generator before we sell. This ensures a full turnkey generator that’s ready to fire up and go!

Due to our wide selection of generator sets, we’re confident that we can find the model that best suits your operational needs and budget.

We also buy used generators in good quality, if you have already upgraded and you’re looking to sell your older model.

Feel free to contact us with any questions, concerns, or inquiries to learn more about the Woodstock Power Company experience and the quality level of products & services we provide.

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