A standby generator does not automatically need a poured concrete slab.
Depending on the model and local code, the generator may be installed on:
- Factory composite base
- Composite mounting pad
- Compacted gravel
- Concrete pad
The right base is the one that satisfies:
manufacturer + soil/site conditions + local code
Composite Pad Advantages
A composite pad is often:
- Faster to install
- Lighter
- Cleaner
- Ready immediately
- Less labor-intensive
It can be ideal for standard residential air-cooled generators where approved.
Composite Pad Disadvantages
Potential drawbacks:
- Not approved for every model
- May require excellent base preparation
- May not satisfy local anchoring rules
- Less suitable for some large/heavy units
Concrete Pad Advantages
Concrete offers:
- High stability
- Strong anchoring base
- Long service life
- Good fit for larger units
It can be useful where wind anchoring, poor soil or local code requires it.
Concrete Pad Disadvantages
Concrete usually means:
- More labor
- Higher cost
- Additional scheduling
- Cure time
- Harder relocation later
Direct-to-Dirt Composite Bases
Some air-cooled Generac units use a factory composite base designed for placement on properly prepared level ground.
Generac installation guidance also supports pea-gravel or concrete base preparation on applicable units.
Gravel Under Composite Pad
A compacted gravel base can improve drainage, leveling and stability.
For applicable Generac air-cooled installations, approximately 5 inches of compacted pea gravel has been used in manufacturer guidance.
Which Is Better for Hurricane Areas?
Concrete may be preferable or required where the installation needs engineered anchoring.
Use local wind-code and manufacturer requirements.
Bottom Line
Choose concrete when the site or code needs concrete.
Choose composite/gravel when the exact generator is approved for it and site conditions are good.
Read generator pad requirements →