MaxJax - Next to Wall - new slab recommendations

[hyperplus]

Hi! - I am new to GarageJournal - so trying to catch up with reading here. Will appreciate tips (on what to read) on how to re-pour a slab when next to the wall? And any other comments / questions..

Attached photo is my 3rd garage bay when new and where I plan to put the lift. From "the paper" seems to be 4" with 3k psi, which I plan to redo the slabs.

• The garage bay there has a working area of 20' deep x 12' wide x 10' height
• Planning to install lift 9'..10' deep, not sure wide yet..
• Lift Left Post needs to be against the wall (close to garage foundation)
• Most cars are 4-5k pounds

My main research at the moment will be that Left Post slab.. Trying to figure the specs on rebar style and gauge, deepness of the hole etc.. Thinking that because its so close to the wall.. I might not want to drill and anchor to it.. and instead use deeper "bent support" rebars that are "standalone". I really don't know at this point.. so trying to educate myself on options.. and should I consider epoxy anchors on the left?


Thanks!

 

[gmcgeo]

General slab specs for a lift include a minimum thickness of six inches, but eight to twelve inches is ideal at the post locations. Use concrete with a strength rating of four thousand to five thousand PSI. Reinforcement should include half-inch rebar spaced twelve inches apart in a grid pattern. If going deeper than eight inches, consider a double layer of rebar. For the footing under each post, pour a pad that is twenty-four by twenty-four to thirty-six by thirty-six inches and ten to twelve inches deep. Reinforce it with cross-tied rebar in two or three layers.

When it comes to anchoring the post near the wall, you have two main options.

Option A is to pour a monolithic pad without attaching it to the wall. Dig and pour an isolated, independent slab pad that does not touch or anchor into the foundation. Use hooked or bent rebar in an L or U shape to reinforce the pad downward and laterally. Make sure to separate the new slab from the wall using expansion foam or an isolation joint.

Option B is to use epoxy anchors if absolutely necessary. You can epoxy anchor into the foundation only if you confirm the foundation is thick enough to handle the load. Maintain a safe edge distance, ideally ten times the anchor diameter. Use a structural epoxy like Hilti RE 500 V3. Always consult a structural engineer before anchoring into the wall for a load-bearing application. Anchoring into the wall should be a last resort. A standalone reinforced pad is typically safer and more reliable.

 

[hyperplus]

Thanks! This helps a lot to google more etc. Sounds like option A for me.

 

[hyperplus]

@gmcgeo - forgot to ask.. when rebar goes into the existing 4" slab.. how many inches in?

.. asking for a friend.

 

[lolaetype]

Hi! - I am new to GarageJournal - so trying to catch up with reading here. Will appreciate tips (on what to read) on how to re-pour a slab when next to the wall? And any other comments / questions..

From the MaxJax web site:

What You’ll Need to Check to Install Your MaxJax:​

• Concrete Slab Thickness (4.25” or more)
• Concrete-MaxJax Indoor Installation Only
• Concrete-No More Than 3-degree Slope
• Concrete-Compressive Strength 3,000 psi or Greater
• MaxJax Lift Location
• Overhead Clearance, Approach Clearance, and Obstructions
• Concrete Condition (no significant cracks or defects, especially under lift pillars)
• Traditional Slab or Post-Tension Cable Slab type verified
• Note-MaxJax hold-down bolts/anchors require 90 ft-lb tightening torque

 

[hyperplus]

Thanks @lolaetype! - this is why I am doing the slab to be safe. Seems I am on the right path.. remaining question is the rebar into 4" when I cross / mesh them.. how many inches should I drill in? 6"-8"? guessing the hole will be like 8"..12" deep horizontally?..

 

[lolaetype]

Thanks @lolaetype! - this is why I am doing the slab to be safe. Seems I am on the right path.. remaining question is the rebar into 4" when I cross / mesh them.. how many inches should I drill in? 6"-8"? guessing the hole will be like 8"..12" deep horizontally?..

If you are using the MaxJax supplied anchors You only need to drill down a bit more then the length of the anchor itself. MaxJax tech support should have the answer and I'd encourage you to call them, but I'd guess maybe 1/2" to 1" more.

 

[ericm]

Lift manufacturer's install instructions say what thickness, psi, etc and also how close to the wall, joint or hole the lift can be.

There are usually two sets of specs- one for the entire slab, and one to use when the slab doesn't meet the first set of specs and you have to cut a section out and pour a new section to suit. That one usually is thicker and needs to be keyed into the existing slab.

 

[hyperplus]

My current garage is not to spec as is 4" vs 4.25"... and is probably 3k psi.. I been trying to contact the builder but no luck yet.

So to be safe I am going with "new slab" which only fits close to the garage wall. I have seen (youtube) many people doing that.. not ideal.. but a stiffer slab should be enough. And not have to anchor to foundation..


The missing question - is the "new rebars"... I see they are drill horizontally to the 4" existing concrete.. So about how much in should I go?.. Guesing if I make a slab hole of 36"... those new rebar needs to be longer? like 42" (3" in per side) so I can anchor them in the existing concrete by drilling holes of about 6" and add epoxy in to those holes?

This image is a quick guess..

• Purple = L / U rebar
• Black = straight rebar

The new rebars will anchor to existing concrete before the fill up.

 

[ericm]

You should be asking the lift manufacturer these questions.

 

[Mr onetwo]

I want to know how you are going to use this lift with a post right against the wall? After you pull the car in how do you plan to get the arms set? Askin' for a friend

 

[Denwood]

Did this slab mod about 11 years ago for my MaxJax, likely overengineered. Zero issues with a lot of lift use. The thread will help with your questions

A few quick tips. Don't use the mechanical anchors..the epoxy are much better, particulary after a few years as you check and re-torque.

You can excavate 4-6" under the existing slap instead of rebar. At your wall, where you're against the footing, you can epoxy in 6-8 rebar anchors, 5/8" will be lots.

I did not pour "pads" but a reinforced strip right across the two mount points. This is much stronger in all respects, and I've shown that the weight of this pad itself would be enough to keep the lift safe. See post #7.

MaxJax Install - Concrete too thin!

I've been working on a garage reno, which includes a MaxJax lift. This lift will see an Audi A3, 1990 VW Westfalia van, and Honda CRV. When drilling anchor holes for epoxy inserts to bolt the lift down, it was evident the slab was way too thin. Doing some research, I found a spec for a...

www.garagejournal.com

 

[hyperplus]

I want to know how you are going to use this lift with a post right against the wall? After you pull the car in how do you plan to get the arms set? Askin' for a friend

This is what I mean.. similar setup to them.. which is not to spec to the spacing documentation from the wall

 

[mepstein]

Put it too close to the wall and it will be a pita to work on the side of the car. It's also nice to be able to walk back and forth when the car is on the ground. That's impossible if the post is butted up against the wall.

 

[hyperplus]

Put it too close to the wall and it will be a pita to work on the side of the car. It's also nice to be able to walk back and forth when the car is on the ground. That's impossible if the post is butted up against the wall.

Totally agree.. but is the best option I see here.. 3rd garage will be just parking my toy car or swapping when needing to do mechanics..

Lately this month I really which I had this. Between S4 slave cylinder burst, new spacers vibrations.. just got an old TT and just doing the cat on it.. prev owner had decat.. oil changes and tires.. even my wifey asks when I am getting the lift

 

[mepstein]

Nobody ever said they regret getting a lift.

 

[hyperplus]

On good news.. Bendpak has a bug in the July 4th sales.. Just got the Ultimate + Motorcycle for $4500... let's see if they honor it... TBC