Designing a Generator Pad

designing a generator pad

So, you’ve made the decision to purchase a backup generator for your home or business. Congratulations! Now, there are a few details to consider in order to get the most out of this investment: airflow, fuel availability, exhaust flow, sound barriers, etc.

Included on this list is making sure you have the right generator pad. Some manufactures have ready-made concrete slabs that you can purchase with your generator. Others need to be custom-designed to your space. If you need one custom-fitted, here are a few considerations for designing a generator pad.


The size of a generator pad refers to how large the pad footprint will be. This is likely the quickest and most simple to determine for your generator pad design. Using the generator footprint, simply add your desired clearance to all sides to determine the overall footprint of the pad. Look at your generator manufacturer’s recommendation for help determining clearance. Many manufacturers recommend a minimum of 6-12 inches clearance on all sides. A properly designed pad will allow enough clearance on all sides to allow technicians to stand on the pad while servicing or repairing generators.


When determining the composition of the generator pad, consider what type of concrete mixture is suitable for the application. Again, refer to the generator manufacturer for details on what is recommended. The recommended concrete mixture for many manufacturers by volume is 1:2:3 parts of cement, sand, and aggregate, respectively. (Note: you will use this composition to determine the density of the pad. This, in turn, will help you determine the thickness of the pad.)


To determine the proper thickness of the generator pad, consider the weight that it needs to support (the weight of the generator itself). For the pad to be structurally sound, it has to weight equal to, or greater than the generator. Calculate the total volume required by dividing the overall weight by the density. Then, calculate the thickness of the pad by dividing the total volume by the surface area (size, or footprint).

Conduits/Stub-up Areas

Considering conduits and stub-up areas is perhaps the most important aspect of designing a generator pad. The conduit cannot change location once the concrete is poured, so precision from the get-go is important. Depending on the generator, this can be difficult. Ideally, the conduit is brought up directly under the junction box where the load leads connect to the breakers or alternator bus.

No Need to DIY When Designing a Generator Pad!

A properly sized generator pad can make a generator last longer, be easier to service and maintain, and can impact the function of the generator itself. Obviously, there is a lot to consider when designing a generator pad. The pad must meet a certain set of criteria and can be tricky to design. Because such precision is required, it’s best to leave the design process to the experts. Avoid costly mistakes and contact the engineering department at Midwest Generator Solutions to design a generator pad specific for your project.

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