Just for shits and giggles I copied this from BendPaks site.
Depending on the lift, they don't start recommending 5" of concrete until you get upwards of 35K on some of them. others go up to 8" but that's more then most of us need to lift.
Lift owners and end users are responsible for the safe installation of their lift. The figures below represent suggested concrete specifications, but should not be construed as actual requirements for your building, facility or application. Because local and statewide building codes may change and / or vary, always check with the building architect before installation for additional guidance on UBC compliance requirements. In no event shall BendPak Inc. be liable for special, consequential or incidental damages for the misinterpretation of this information. BendPak Inc. reserves the right to make changes to this document without incurring any obligation to notify the public that changes were made.
4-POST LIFTS
DESCRIPTION
MIN. CONCRETE SPECS
HD-9ST-B
9,000-lb. Capacity / Four Post Lift / Narrow Width
3-1/2" Min. Thickness / 2,500 psi
HD-9-B
9,000-lb. Capacity / Four Post Lift / Standard Width
3-1/2" Min. Thickness / 2,500 psi
HD-9STX-B
9,000-lb. Capacity / Four Post Lift / Narrow Width
3-1/2" Min. Thickness / 2,500 psi
HD-9XW-B
9,000-lb. Capacity / Four Post Lift / Standard Width
3-1/2" Min. Thickness / 2,500 psi
HD-14SS
14,000-lb. Capacity / Space Saver
4" Min. Thickness / 2,500 psi
HD-14
14,000-lb. Capacity / Extended
4" Min. Thickness / 2,500 psi
HD-14X
14,000-lb. Capacity / Extended / Limo Style
4" Min. Thickness / 2,500 psi
HD-14STL
14,000-lb. Capacity Tall Lift / Space Saver / 82" Rise
4" Min. Thickness / 2,500 psi
HD-14ETL
14,000-lb. Capacity Tall Lift / Extended / 82" Rise
4" Min. Thickness / 2,500 psi
HD-18
18,000-lb. Capacity / Standard
4" Min. Thickness / 2,500 psi
HD-27
27,000-lb. Capacity / Standard
4" Min. Thickness / 2,500 psi
HD-27X
27,000-lb. Capacity / Extended
4" Min. Thickness / 2,500 psi
HD-35
35,000-lb. Capacity / Standard
5" Min. Thickness / 2,500 psi
HD-35X
35,000-lb. Capacity / Extended
5" Min. Thickness / 2,500 psi
HD-40
40,000-lb. Capacity / Standard
5" Min. Thickness / 2,500 psi
HD-40X
40,000-lb. Capacity / Extended
5" Min. Thickness / 2,500 psi
HD-14LS
14,000-lb. Capacity / Alignment
4" Min. Thickness / 2,500 psi
HD-14LSX
14,000-lb. Capacity / Alignment / Extended
4" Min. Thickness / 2,500 psi
HD-14LSXE
14,000-lb. Capacity / Alignment / Limo Extended
4" Min. Thickness / 2,500 psi
HDO-14LSX
14,000-lb. Capacity / Alignment / Extended / Open Front
5" Min. Thickness / 2,500 psi
HD-18A
18,000-lb. Capacity / Alignment
4" Min. Thickness / 2,500 psi
HD-27A
27,000-lb. Capacity / Standard / Alignment
4" Min. Thickness / 2,500 psi
HD-27XA
27,000-lb. Capacity / Extended / Alignment
4" Min. Thickness / 2,500 psi
HD-35A
35,000-lb. Capacity / Alignment
5" Min. Thickness / 2,500 psi
HD-35XA
35,000-lb. Capacity / Extended / Alignment
5" Min. Thickness / 2,500 psi
XR-12AE
12,000-lb. Capacity / Scissors Alignment
4" Min. Thickness / 2,500 psi
2-POST LIFTS
DESCRIPTION
MIN. CONCRETE SPECS
XPR-9F
9,000-lb. Capacity / Floorplate / Chain-Over / Narrow
4" Min. Thickness / 3,000 psi
XPR-9FX
9,000-lb. Capacity / Floorplate / Chain-Over / Wide
4" Min. Thickness / 3,000 psi
XPR-9FD
9,000-lb. Capacity / Floorplate / Direct-Drive / Narrow
4" Min. Thickness / 3,000 psi
XPR-9FDX
9,000-lb. Capacity / Floorplate / Direct-Drive / Wide
4" Min. Thickness / 3,000 psi
XPR-12FD
12,000-lb. Capacity / Floorplate / Direct-Drive
6" Min. Thickness / 3,000 psi
XPR-10C
10,000-lb. Capacity / Clearfloor / Narrow
4" Min. Thickness / 3,000 psi
XPR-10CX
10,000-lb. Capacity / Clearfloor / Wide
4" Min. Thickness / 3,000 psi
XPR-10AC
10,000-lb. Capacity / Asymmetric Clearfloor / Narrow
4" Min. Thickness / 3,000 psi
XPR-10ACX
10,000-lb. Capacity / Asymmetric Clearfloor / Wide
4" Min. Thickness / 3,000 psi
XPR-12C
12,000-lb. Capacity / Clearfloor / Triple-Telescope Arms
6" Min. Thickness / 3,000 psi
XPR-15C
15,000-lb. Capacity / Clearfloor / Standard Arms
6" Min. Thickness / 3,000 psi
XPR-18C
18,000-lb. Capacity / Clearfloor / Standard Arms
8" Min. Thickness / 3,000 psi
SCISSOR LIFTS
DESCRIPTION
MIN. CONCRETE SPECS
XR-12AE
12,000-lb. Capacity / Scissors / Alignment / Extended
4" Min. Thickness / 2,500 psi
SP-7X
7,000-lb. Capacity / Scissors / Full-Rise Platform Style
4" Min. Thickness / 2,500 psi
SPECIALTY LIFTS
DESCRIPTION
MIN. CONCRETE SPECS
PL-6SP / PL-6000
6,000-lb. Capacity Single Post Parking Lift / Deck
4" Min. Thickness / 3,000 psi
PL-6SPX / PL-6000X
6,000-lb. Capacity Single Post Parking Lift / Deck / Extended Rise
4" Min. Thickness / 3,000 psi
PL-7 / PL-7000
7,000-lb. Capacity / Two-Post Parking Lift / Deck / Standard Rise
4" Min. Thickness / 3,000 psi
PL-7X / PL-7000X
7,000-lb. Capacity / Two-Post Parking Lift / Deck / Extended Rise
4" Min. Thickness / 3,000 psi
LR-60 / LR-6000
6,000-lb. Capacity / Low-Rise Lift
3-1/2" Min. Thickness / 2,500 psi
LR-60P / LR-6000P
6,000-lb. Capacity / Low-Rise Lift / Portable
3-1/2" Min. Thickness / 2,500 psi
MD-6XP
6,000-lb. Capacity / Mid-Rise / Frame Lift / Portable
3-1/2" Min. Thickness / 2,500 psi
P-6 / P-6000
6,000-lb. Capacity / Low-Rise Lift / Pit-Style
3-1/2" Min. Thickness / 2,500 psi
P-6F/ P-6000F
6,000-lb. Capacity / Low-Rise Lift / Pit-Style / Flush Mount
3-1/2" Min. Thickness / 2,500 psi