More Concrete Slab Questions

[raynman1972]

(I am posting this from my phone using an app so I apologize if this looks like **** in your browser- 1st time trying this)

Background:
I have a 20x30 shop that is almost 2yrs old and it has a 4" slab that I am told has no rebar and was poured directly over sand (gravel not required by local code). Also, given the other details, I have to guess the concrete is anything higher than 3000psi. The good news, for what it's worth, is that the pad has no cracks and looks good.

Goal:
I would like to put in a 2-post lift like the 9' Bendpak or Rotary because I have a 10' ceiling. I realize that I will only get 3-4' of lift with my ceiling but I like these lifts over scissor-alternatives because I think I can use one of these to lift the body off of the frame or even pull a canopy off my Blazer.

Questions:
1. I have done a few hours of research and I am pretty sure that I really have no basis for installing a lift on my lightweight concrete, right?
2. Are my only options are to either use a scissor lift (assuming these are better with sketchy concrete due to larger footprint) or to cut, dig and pour new footings?
3. Are there any selling points that I am missing with a scissor lift? Other than how I want to use the lift, I am not crazy about the more limited access due to the broad lifting plates.
4. Are there any alternatives that I missed in my research?

Thank you for taking the time to read through all of this rambling!


Sent from my iPhone using Tapatalk

 

[ymurf]

Maxjax only requires 4" of concrete.

 

[DougWil]

Hopefully you can find a lift so you don't have to, but it really isn't a big deal to saw out a square hole and put in a spread footing.

 

[USAFpj]

A true 4 inches of concrete is perfectly acceptable in most requirements. To ensure this, just research the lift manufacturer and their requirements. If in doubt about if it's a true 4 inches, then you may have to take a sample from the area you want to place the concrete.

 

[matemike]

you could do a flush mount scissor lift install like this:

http://www.garagejournal.com/forum/showthread.php?t=35433&showall=1

the lift itself is surprisingly cheap. you just have to decide if you're willing to do that much work to install it properly. this would without a doubt be the biggest space saver in you garage as well.

 

[raynman1972]

A true 4 inches of concrete is perfectly acceptable in most requirements. To ensure this, just research the lift manufacturer and their requirements. If in doubt about if it's a true 4 inches, then you may have to take a sample from the area you want to place the concrete.

I didn't think the 4" @3000psi and with no rebar would be okay for a lift (understanding that the requirements can vary). I thought that from my research here that I didn't have enough strength for anything really.

 

[raynman1972]

you could do a flush mount scissor lift install like this:



http://www.garagejournal.com/forum/showthread.php?t=35433&showall=1



the lift itself is surprisingly cheap. you just have to decide if you're willing to do that much work to install it properly. this would without a doubt be the biggest space saver in you garage as well.

I saw that today and I thought it looked really cool. I like the space savings but the amount of work would be an investment. Also, pretty sure I can't pull the body off my Blazer with one of those (unless I am missing something).

 

[cj7jeep81]

I saw that today and I thought it looked really cool. I like the space savings but the amount of work would be an investment. Also, pretty sure I can't pull the body off my Blazer with one of those (unless I am missing something).

You'll just have to pick your lift and check. Here are some of the lifts from BendPak, and looks like all of these would work.

http://www.bendpak.com/support/frequently-asked-questions/

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

 

[wssix99]

1. I have done a few hours of research and I am pretty sure that I really have no basis for installing a lift on my lightweight concrete, right?

Most lifts just call for a minimum of 4" and 3000 psi. Often, contractors will use a higher strength than that to get a better finish on the slab. Rebar does not make the slab "stronger" like it would in a concrete beam or column. In a slab, rebar just helps control cracking. (Likewise, you will typically not see any requirements from lift manufacturers if you are pouring a new slab.)

The big thing is the full 4" depth. If it turns out that you don't have that, you'd need to cut out a section and put in a specially designed repair slab for the lift, which would be pinned or keyed in to your larger floor.

 

[readhead]

This also assumes that there is sufficient soil bearing under the 4" of concrete.