How thick of pad do you have?

[swampymarsh]

After about 9 months fighting with the city on zoning laws and building permits I finally have the go ahead to start building my 30 x 40 x 10 garage.

I origionaly (sp?) had planned on a 6 in thick floor but now I'm starting to wonder if an 8 in would be better. For the cost of an additional $800 it seems like it would be worth it since I'll need the extra weight bearing ability for the lathe, mill, lift etc.

What has everone else poured? recommendations?

Thanks

Dave

 

[boiler7904]

I wouldn't bother doing 8" everywhere. It's overkill. If the equipment layout isn't 100% nailed down yet, I'd probably do that entire bay or half bay - whatever the machining area comes down to.

Most lift manufacturer's say that you don't need anything special in terms of footings for there lifts. Personally, I'd pick a spot for it and pour an 8" deep slab at each post reinforced with a few #5 bars in each direction - just leave a piece of vertical rebar flush with the surface at the center of each pad so you can know for sure where they are when it comes time to install the lift.

What are you planning to heat the shop with? Nows the time to install foam insulation under the slab and radiant tubing in the slab even if aren't going to use it for a while. If you don't use the whole $800 for the extra slab thickness, you could probably get the tubing for $400-500 bucks. Insulation will be about $800 or so depending on where you live.

 

[swampymarsh]

Thanks for the input. I've had garages w/out radient heat....this one's going to have it!!

Dave

 

[bluesman2a]

I have a 6" thick slab for the most part. I'd agree with Boiler though. On mine I placed 2 3X3 caissons under where the lift got mounted approximately 2' deep. Also had them put the rebar down about 12" from the bottom of the holes so as not to hit it when mounting the lift.

 

[jpracer1]

you could request a mix with 1 1/2 rock for strength and probably a 7 sack mix.the big rock gives the mix more to bond to and at a less cost

 

[SC-Eric]

I'm a big fan of overkill... lol..

I'm always trying to anticipate what I might want or need to do sometime down the road. On thing is for sure, if you ever wanted to expand... or... just needed to move the heavy stuff (for a reason you can't think of now), it's alot cheaper to add the extra 2" now than when you find out you really DID need it.

Wolvie $0.02

 

[1carguy]

If it were my garage, I would not waste the money on 8" or any special footings for the lift. I would stick with 4" 3000 PSI (pounds per square inch) concrete. I have 3 lifts in my garage on 4" with no special footings and have had no problems.

Consider this: Say you have a car on the lift that weighs 4,000 lbs and the lift weighs perhaps a thousand pounds. Divide this by 4 posts which means that each 4"x4" or 16 square inch post base is carrying 1250 pounds each or 78 pounds per square inch (1250/16). Besides, my experience is that no matter how much I plan the lift ends up being best used slightly to the left or right of where I had planned. When you get ready to sell no one is going to pay you any more for the home because the concrete is deeper than the norm of 4".

Just my 2 cents.

 

[67 455 Bird ragtop]

My slab is 4" overall with 6" where I will mount my lift.

 

[bluesman2a]

If it were my garage, I would not waste the money on 8" or any special footings for the lift. I would stick with 4" 3000 PSI (pounds per square inch) concrete. I have 3 lifts in my garage on 4" with no special footings and have had no problems.

I must respectfully disagree here, based on my own experience. 4" 300PSI is MIMIMUM recommended by manufacturers for a TWO post lift. Sorry but I'm not comfortable working under a 6500# vehicle with MINIMUM safety margins. Each of my piers cost me $180 extra. I think that's money WELL spent if you plan on a 2-poster. Yes, with a FOUR post, I absolutely agree with you.

For my particular setup it was only another $400 total to step up from 4" to 6", so again I consider it money well-spent... Your particular project may vary though.

 

[Kevin54]

I origionaly (sp?) had planned on a 6 in thick floor but now I'm starting to wonder if an 8 in would be better. For the cost of an additional $800 it seems like it would be worth it since I'll need the extra weight bearing ability for the lathe, mill, lift etc.

For no more than what it cost, I would say go for it. Then you know that where ever anything is set, that you don't have to "wonder" if you are on top of a piling or not. Also if and when any of the fill settles over the years, the extra thickness will aid to bridge any voids. And if no one thinks they get voids, just walk around with something like a spud bar and thump the concrete under your slab. You will find the hollow spots.

Kevin

 

[Vicegrip]

The thickness and PSI rating is for anchor retention. Anchors that are most often supplied by the lift maker. You can have a 10 foot thick slab and the fail point is still the anchors pulling out of the concrete.

 

[Mr. Welsh]

6" is already overkill unless you plan to have semis and heavy equipment moving around. A little extra under a two post lift doesn't hurt, but to do 8" all around you might as well throw a bunch of twenties into the mix, imo. Plus it may cause issues with your radiant heat.

 

[boiler7904]

6" is already overkill unless you plan to have semis and heavy equipment moving around. A little extra under a two post lift doesn't hurt, but to do 8" all around you might as well throw a bunch of twenties into the mix, imo. Plus it may cause issues with your radiant heat.

6" will not stand up to semis or heavy construction equipment on a day-in, day-out basis. Occassional use maybe. We always design at least 8" with 1 or 2 rebar mats depending on actual equipment loading. Last one was more like 12" with 2 mats of #4 bars at 12" o.c. on a pretty deep gravel base.

 

[swampymarsh]

6" is already overkill unless you plan to have semis and heavy equipment moving around. A little extra under a two post lift doesn't hurt, but to do 8" all around you might as well throw a bunch of twenties into the mix, imo. Plus it may cause issues with your radiant heat.

Why do you say that that it may cause issues with the radiant heat? Yes it may take slightly longer to heat up and cool down, if you consider that a draw back. Please help me uderstand your thinking....

Dave

 

[D KRAGER]

What type of soils do you have??? The base under the crete is just as important as the crete itself. If you have poorly drained soil and little rock fill under it, 6-8" may not be overkill. If you are elevated, have a deep rock foundation, and the area is tiled to get rid of excess water, 4-6" may be adequate.