Question about cement pads

[Hunter55]

Hi all, long time lurker here.

I'm in the process of building a garage, and am currently getting estimates for a concrete pad. The garage is one of those pre-built structures that gets delivered and dropped onto the pad. The builders of the garage say that they require a 4" monolithic pad minimum, not listing a psi rating. I've googled around and read up on the subject, but I'd like to know what PSI some of you chose for your garages. Also, I've decided that I want a smooth finish for the floor. One of the contractors who came out to give me a quote, quoted me one price for the standard brushed finish, and then said it would be an extra thousand dollars for a smooth finish. He claims it would be more work. The other contractor who came out quoted me one price for either or. Is creating a smooth finish a much more intensive process than a brushed finish, and if so, does $1000 extra sound about right (pad is a 14x26 btw)

P.S. for the PSI rating, I should mention that I plan to put in a lift at some point.

 

[plugers]

I think the standard mix is 3500psi, we usually poured 4000psi with limestone aggregate, if you're somewhere that freezes in the winter. or 6 sack limestone mix.

 

[ConCretin]

I'd suggest going with a 4000 psi concrete. The higher compressive strength isn't really needed from a structural standpoint but the additional cement will help provide a tough, durable surface.

It is more time consuming to do a smooth trowel finish simply because you need to wait longer for the concrete to set up a little more. Prices vary around the country but $1000 seems a little ridiculous for one or two guys to hang around a couple extra hours. I'd keep looking.

 

[astroracer]

Most two post lift (up to 9 or 10k) manufacturers recommend 4" min thickness at 3000psi. Anything beyond that and you have zero concerns.
And just so you are aware, a 14' wide garage will be hard pressed to have room for any kind of lift. You have to realize your 14' dimension is to the outside of the structure. Wall thickness, 2 x 4 or 2 x 6, will cut that down to less then 13' on the inside real quick. Most 2 post lifts are 11 or 12' wide, you will have no room to walk or work between the outside of the posts and either wall.
Mark

 

[Retroman]

Everything we pour is 4500 psi you will be fine with 4000 psi. ask your contractor for a power trowel finish. that gives you a nice hard smooth finish. No should not be a extra 1K maybe $250 if that.

 

[billfires]

just did a 24x40, 6" thick, 4000 psi mix. I paid $1300 that included the materials for the forms, spreading the concrete, and a smooth, hand troweled finish. Power trowel would have been the same price. I am awaiting the erection of my steel building also. Bill C




'

 

[Hunter55]

Thanks for the replies everyone. So the top two contenders right now each quoted me at 4500PSI and 5000PSI, so I think I'm good in that respect.

Most two post lift (up to 9 or 10k) manufacturers recommend 4" min thickness at 3000psi. Anything beyond that and you have zero concerns.
And just so you are aware, a 14' wide garage will be hard pressed to have room for any kind of lift. You have to realize your 14' dimension is to the outside of the structure. Wall thickness, 2 x 4 or 2 x 6, will cut that down to less then 13' on the inside real quick. Most 2 post lifts are 11 or 12' wide, you will have no room to walk or work between the outside of the posts and either wall.
Mark

You make a good point, but unfortunately, I'm limited in width by the pathway that the delivery mule has to take to deliver the garage (and of course, a traditional stick-built is way too costly here in NY). I originally wanted a 16' wide garage for this very reason, but have made peace with the 14' limitation.

 

[astroracer]

You may want to add a man door towards the back of the garage so you can access it with a car in the garage. You will have no room to get to the back with a car sitting on the floor between the lift posts.
Mark

 

[FlavortownPublicWorks]

just did a 24x40, 6" thick, 4000 psi mix. I paid $1300 that included the materials for the forms, spreading the concrete, and a smooth, hand troweled finish. Power trowel would have been the same price. I am awaiting the erection of my steel building also. Bill C

'

Labor must be cheap in your area! My 5" garage floor was about $3000 for 20x30, with rebar 32" om center. That's not even counting the $4500 for the foundation and footings!

 

[Falcon67]

just did a 24x40, 6" thick, 4000 psi mix. I paid $1300 that included the materials for the forms, spreading the concrete, and a smooth, hand troweled finish. Power trowel would have been the same price. I am awaiting the erection of my steel building also. Bill C
'

Where the heck is this - 7 years ago I got a bargain on a 24x40 at $4500. Minimal footers, 4000 psi, 4". You could not buy the 'crete here for $1300, it's at least double that figure delivered. Not set, no forms, etc.

 

[b-boy]

just did a 24x40, 6" thick, 4000 psi mix. I paid $1300 that included the materials for the forms, spreading the concrete, and a smooth, hand troweled finish. Power trowel would have been the same price. I am awaiting the erection of my steel building also. Bill C
'

Did that include fill and site prep?

Last year I did a 30'x40' 4" un-insulated floor with rebar that required several truck loads of fill (plus compacting). I paid 7K.

 

[8mpg]

Im thinking that guys is saying $1300 for labor only. There is no way he had it poured for $1300. That's just over $1/ft

 

[PWC Repair]

Go with 4000psi and make sure the rebar or webbed wire is up on rocks/bricks/chairs, whatever. Just not pulled up with a rake, it ends up on the bottom of the slab doing nothing. You DONT want a brushed finish inside the garage, you want power troweled smooth. Floated out with an aluminum float by somebody that knows what they're doing at least.

 

[b-boy]

Floated out with an aluminum float by somebody that knows what they're doing at least.

That's the key. Finding a guy who knows what he's doing. The guy I hired was a bit wacky, but he came highly recommend. I was a little worried at first.

After the pour. he showed up at my house at 2AM to check on everything. I thought someone was robbing me, but it was just him. The weather was a little colder than he anticipated, so he brought heaters to heat the pole barn. He showed up every few hours for the next couple of days to make sure the fuel levels were good.

He did a fantastic job. I've had multiple people comment on the finished work.

 

[billfires]

Sorry for the confusion. The $1300 was for labor and forms. It took 17 yards of concrete that was $1860 with tax. I did the site prep and they cut down a couple of high spots. Bill C

 

[protegeV]

Sorry for the confusion. The $1300 was for labor and forms. It took 17 yards of concrete that was $1860 with tax. I did the site prep and they cut down a couple of high spots. Bill C

Still not bad. I just paid $17k for my slab and it was 75yd of concrete. I got 4 quotes and the I went with the one that was the cheapest.

Say, how big were your footers? Mine is a 40x60 6" yet it took more than 4x as much concrete

 

[Bighead38]

Thanks for the replies everyone. So the top two contenders right now each quoted me at 4500PSI and 5000PSI, so I think I'm good in that respect.



You make a good point, but unfortunately, I'm limited in width by the pathway that the delivery mule has to take to deliver the garage (and of course, a traditional stick-built is way too costly here in NY). I originally wanted a 16' wide garage for this very reason, but have made peace with the 14' limitation.

Where in NY?

 

[billfires]

Still not bad. I just paid $17k for my slab and it was 75yd of concrete. I got 4 quotes and the I went with the one that was the cheapest.

Say, how big were your footers? Mine is a 40x60 6" yet it took more than 4x as much concrete

No footer. Was originally going with a monolithic pour with a 4" slab, but decided on 6" slab for the whole thing. The inspector felt that the steel building I am installing has very little weight to it so he would have been ok with a 4" slab.

 

[protegeV]

No footer. Was originally going with a monolithic pour with a 4" slab, but decided on 6" slab for the whole thing. The inspector felt that the steel building I am installing has very little weight to it so he would have been ok with a 4" slab.

Well that explains the yardage and cost difference

 

[cupcakemike]

Still not bad. I just paid $17k for my slab and it was 75yd of concrete. I got 4 quotes and the I went with the one that was the cheapest.

Say, how big were your footers? Mine is a 40x60 6" yet it took more than 4x as much concrete

Well, yeah, even without footers your square footage is damn near 3x as much!

Usually you can get full trucks of ready mix delivered for $100-120 a yard, double the cost of the concrete to cover labor and rebar/forming and you should be in the neighborhood, if there isnt much site prep necessary...