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2-Column Car Jack Installation: Optimal Hole Dimensions and Anchor Recommendations for Concrete B25

Pio5311 34314 17
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How deep and wide should the concrete foundations be for a 2-column car lift, and what anchors and reinforcement should be used in weak garage concrete?

The safest answer is to follow the lift’s DTR/manual, because the required foundation dimensions are specified there; one user with a Stenhoj 2.3F reports a base about 90 cm wide, 450 cm long and at least 30 cm deep, using B25 concrete and steel studs for mounting, and he poured it about 110 × 450 × 40 cm [#16989308][#16990001] Several replies recommend making one reinforced bench under both columns instead of two separate holes, because the lift produces significant pull forces and the base should be tied together [#16989580][#16989924] Suggested reinforcement includes 4× fi12 bars or at least 2 fi12 bars around the foot, and connecting the column bases with a reinforced beam (for example 40×40 or a roughly 2 m reinforced beam) [#16989814][#16989924][#16990226][#16989876] For anchors, one reply mentions 18 mm anchors, while another says the installation used steel studs [#16989924][#16990001] If you build it, check the anchor tightness again after a week or two [#17004758]
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  • #1 16988265
    Pio5311
    Level 3  
    Posts: 147
    Rate: 66
    Hello .
    On days I will be preparing the floor for the assembly of a 2-column car jack and I have a question.
    So yes, at what depth, width and length should I make holes in the ground so that it is good? Will 70 cm x 70 cm x 70 cm do I do it well?
    Because in general I have a poured floor in the garage, but the concrete is too weak for the lift and a thin layer, so I will make holes for the columns and pour concrete B25, but I mean the dimensions that are to be or if mine that I give will be good.
    And one more question, the lift will be screwed to the anchors, can anyone suggest what to buy?
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  • #2 16989238
    gabik001
    Level 37  
    Posts: 4267
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    I installed such jacks (2) at my brother's workshop and the spout was 6 inches (15cm) thick and that was enough. Generally, in these lifts the pressure force is centrally down below the columns, so with such foundation sizes it will calmly fulfill its task.
    What is the anchor I used to use such mining (they were 30mm in diameter outside) but it was about 20 years ago ...
  • #3 16989308
    kortyleski
    Level 43  
    Posts: 12263
    Help: 957
    Rate: 3835
    Download the lift dtr. There, the foundations will be described and dimensioned.
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  • #4 16989505
    Pio5311
    Level 3  
    Posts: 147
    Rate: 66
    Well, I'll do 70 cm deep, wide and long and I think it's okay.
    And I will not give reinforcements or do you think to give?
    I also think that without the formwork directly In the ground, is it better to plank?
  • #5 16989580
    kortyleski
    Level 43  
    Posts: 12263
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    You should give one bench under both columns. Concrete should always be reinforced so that I can immediately fill in the mounting pins. Somehow I don't trust the anchors and the pulling forces are quite large and it is not true:
    gabik001 wrote:
    Generally, in these lifts the pressure force is centrally down below the columns,
  • #6 16989794
    Pio5311
    Level 3  
    Posts: 147
    Rate: 66
    Well, like a bench under both columns, then I think 30 cm deep enough that the columns protrude from 20 cm and the width then I would make 80 cm And without reinforcement Because this Concrete is hard yet I think there is no need
  • #7 16989814
    Anonymous
    Anonymous  
  • #8 16989851
    Pio5311
    Level 3  
    Posts: 147
    Rate: 66
    Gosh, can't it be just the foundation for the columns?
    I will give a depth of 70 cm And I will give this reinforcement and length and width after 100 cm And I think it will be good and I will not need to pour benches on two columns what do you think about it?
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  • #9 16989876
    Anonymous
    Anonymous  
  • #10 16989901
    kortyleski
    Level 43  
    Posts: 12263
    Help: 957
    Rate: 3835
    2-Column Car Jack Installation: Optimal Hole Dimensions and Anchor Recommendations for Concrete B25

    Please, dump from one of my lifts.
  • #11 16989924
    Strumien swiadomosci swia
    Level 43  
    Posts: 27411
    Help: 1403
    Rate: 6380
    Of course, concrete must have reinforcement because without reinforcement it is only stone, sand and cement with water. And it has to crack that it breaks 100%.
    Secondly, connect these feet with a 40x40 reinforced beam.
    As I remember, the anchors are 18mm and if you fasten them properly, you won't break out for anything.
  • #12 16990001
    RedEd
    Level 11  
    Posts: 37
    Rate: 31
    Stenhoj 2.3F (two screw columns without a connector) if I remember correctly it has requirements for a base 90cm (I gave 110) width 450cm long and minimum 30cm (I gave about 40) depth, concrete min B25 reinforcement not required (I gave it for peace of mind on the bottom layer) the assembly was performed by steel studs.
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  • #13 16990034
    Strumien swiadomosci swia
    Level 43  
    Posts: 27411
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    The point is that when concrete breaks, it will most often scratch on the anchors and will break apart without reinforcement and we have a big problem. Unless the column is placed with the car.
  • #14 16990216
    Pio5311
    Level 3  
    Posts: 147
    Rate: 66
    I don't know if this reinforcement is necessary.
    I work at the workshop And from what I found out they have Concrete B20 I without reinforcement And these are Hoists up to 3t And we also have buses and the same without reinforcement And Concrete b20 I I have a normal long time so I think I will give b25 myself and without reinforcement
  • #15 16990226
    Strumien swiadomosci swia
    Level 43  
    Posts: 27411
    Help: 1403
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    Just 2 wires fi 12 around the foot.
  • #16 16990227
    Pio5311
    Level 3  
    Posts: 147
    Rate: 66
    And I think I will make such dimensions as in this attachment 2-Column Car Jack Installation: Optimal Hole Dimensions and Anchor Recommendations for Concrete B25

    Added after 1 [minutes]:

    What do you think will be okay?

    Added after 5 [hours] 35 [minutes]:

    And one more thing.
    Can I do it myself In a concrete mixer Beton b25?
    Because you know I would buy a few bags of dry and embrace it but I would like to leave b25 instead of b15 :D
    So what it looks like
  • #17 16991648
    kortyleski
    Level 43  
    Posts: 12263
    Help: 957
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    Almost 2 cubic meters of concrete. Modestly counting two pallets of bags ...
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Topic summary

✨ The discussion revolves around the installation of a 2-column car jack, focusing on optimal hole dimensions and concrete specifications. Users suggest that a hole size of 70 cm x 70 cm x 70 cm is generally adequate, but some recommend increasing the width to 80 cm and the depth to 30 cm for better stability. Reinforcement of the concrete is debated, with many advocating for it to prevent cracking and ensure structural integrity, especially under heavy loads. The use of anchors is also discussed, with recommendations for 18 mm diameter anchors and the importance of checking their tightness over time. Users share experiences with different concrete grades, emphasizing the use of B25 for better performance.
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FAQ

TL;DR: For 2‑column car lifts on concrete B25, tie both bases with a 40×40 cm reinforced beam and use ~M18 anchors; “Concrete must have reinforcement.” [Elektroda, Strumien swiadomosci swia, post #16989924]

Why it matters:** This setup resists uplift and cracking, keeping the lift safe and aligned for daily use. This FAQ is for DIYers and shop owners planning holes, rebar, and anchors for a 2‑post lift.

Quick Facts

What hole or base dimensions should I plan for a 2‑post lift?

Follow your lift’s manual first. As a real‑world example, a Stenhoj 2.3F ran on a base about 450×90 cm and 30–40 cm deep in B25, fastened with steel studs. If your slab is thinner, create a reinforced pad or strip footing meeting those depths under both columns. Keep edges straight for anchor accuracy and leave curing time before loading. [Elektroda, RedEd, post #16990001]

Is one strip footing better than two separate footings?

Yes. Join the column feet with a reinforced beam to control differential movement from soil and seasonal changes. A continuous strip reduces racking when the lift cycles and when vehicles sit unevenly. Think of it like tying two gate posts together to stop them from shifting over time. [Elektroda, 266564, post #16989876]

Do I really need reinforcement in B25 concrete?

Yes. Reinforcement handles tension and prevents the base from breaking around anchors. “Concrete must have reinforcement,” especially where uplift acts during lifting. Place rebar around each foot and in any connecting beam, then respect curing time before torqueing anchors. [Elektroda, Strumien swiadomosci swia, post #16989924]

What rebar layout works around each column foot?

Use a simple cage: four longitudinal rods (e.g., 4×Ø12) tied with stirrups. Keep 40 mm concrete cover from soil and formwork. Extend bars into any 40×40 cm tie‑beam between feet so loads share. This minimal steel dramatically increases crack control and anchor pull‑out resistance. [Elektroda, 266564, post #16989814]

Can a 15 cm slab be enough under a column?

Installers report success with a 15 cm (≈6 in) slab when loads are centered and the slab is sound. That said, many lifts specify thicker bases or localized pads. Verify your manual and upgrade to a reinforced pad if your slab is thin or of uncertain quality. [Elektroda, gabik001, post #16989238]

What anchors should I choose and how tight should they be?

Use quality steel studs or ~M18 anchors compatible with your lift base plates. Drill clean, to depth, and torque to spec after the concrete reaches strength. Re‑check anchor tightness after about 1–2 weeks of use to account for settling and micro‑cracking. [Elektroda, phu_szczepan, post #17004758]

Are cast‑in studs safer than post‑installed anchors?

Cast‑in mounting pins provide excellent reliability because they engage the reinforcement and concrete mass. Some installers distrust post‑installed anchors for high uplift unless the base is well reinforced. If you can, set sleeves or studs while pouring the reinforced footing. [Elektroda, kortyleski, post #16989580]

Where can I find the exact foundation and hole sizes for my lift?

Download the DTR/manual for your specific model. Manufacturers include foundation dimensions, anchor patterns, and concrete class requirements. Use those as your controlling document, and treat forum measurements only as examples. [Elektroda, kortyleski, post #16989308]

Can I mix B25 myself in a small concrete mixer?

You can, but volume adds up fast. One user estimated nearly 2 m³ for their plan, which equals roughly two pallets of bagged mix. That is labor‑intensive and time‑sensitive for placement. Ready‑mix delivery improves consistency and finishing time. [Elektroda, kortyleski, post #16991648]

What happens if the concrete cracks around anchors?

Unreinforced pads tend to crack at the anchor line and can break apart under cyclic uplift. That creates a serious safety risk and can topple the column with a vehicle on it. Reinforcement and a tie‑beam reduce this failure mode significantly. [Elektroda, Strumien swiadomosci swia, post #16990034]

How deep should I go if I choose separate pads anyway?

If you avoid a continuous beam, increase pad size and reinforcement to resist uplift and punching. Example installs used 30–40 cm thickness under each column in B25 concrete. Tie pads with rebar if you can, even without a full beam. [Elektroda, RedEd, post #16990001]

What’s a simple 3‑step installation flow I can follow?

  1. Pour a reinforced 40×40 cm tie‑beam connecting both column feet in B25.
  2. Set studs or drill for ~M18 anchors; cure, install, and torque.
  3. Re‑check anchor tightness after 1–2 weeks; then load‑test per manual. [Elektroda, phu_szczepan, post #17004758]

Can I skip formwork and pour directly into soil cutouts?

Use formwork where accuracy matters. Straight, plumb edges keep anchor locations true and help achieve proper cover around rebar. Clean forms also improve finish quality and reduce voids near anchor lines, which limits crack initiation under uplift. [Elektroda, 266564, post #16989876]

What concrete class did others use successfully?

Installers referenced B25 for upgraded bases, with some older shop floors running B20. When in doubt, choose B25 as an example standard and add reinforcement for tensile loads at the anchors and tie‑beam. [Elektroda, RedEd, post #16990001]

Why do some pros dislike relying only on anchors?

Anchors see significant pull when raising vehicles. Without reinforcement or embedded pins, uplift can loosen or pry out anchors over time. Pros prefer casting pins or reinforcing so the system acts as one solid block. [Elektroda, kortyleski, post #16989580]
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