Garage floor replacement quote

[Webosu11]

Long time reader, first time poster here.

I'm in the process of obtaining quotes to replace my existing garage floor. It's a 20x21 floor and the garage is attached to the house (built in '65, Central Ohio region). The current floor is severely cracked and pitted and I believe to be the cause of some foundation issues along the adjoining basement walls (this issue has been addressed with steel I-beams).

I'm looking for some feedback on the first quote I received:

Tear out/Haul away/Pour/Trowel finish/Saw cut/Cure & Seal
4" depth
Gravel (as needed)
6.5 Bag Mix (4500 PSI Grade Cement)
6% Air Entrainment
5" Slump
Fiber Mesh Reinforcement

This contractor recommended to not use a vapor barrier (garage will not be conditioned), rebar, wire mesh, or to tie the slab into the foundation walls (I've received mixed opinions on this). He also said not to park on it for 30 days. He has great reviews on Angie's List and has been in the business for 20+ years.

I'd appreciate any feedback as this is my first time sourcing a concrete job.

Thanks,
Brian

 

[D45]

whats the price?

 

[Dirtydan69]

A location would be good also as weather will affect it.

 

[Webosu11]

I thought the price was reasonable at $4,400. Perhaps I was way overestimating what this job would cost though. I'm located in Columbus, Ohio.

 

[D45]

I think $4,400 is high

I had a new driveway apron done (28'x12'), new skim coat on the front porch, new sidewalk from driveway to front porch, a new 5'x20' section of the garage entrance done and the upper area of my driveway done...…..plus the curb (28') was cut down flush for $6,500

 

[ConCretin]

The price seems like it's in the ballpark to me considering removal and disposal of the existing slab and sub grade prep. A couple additional thoughts;

I wouldn't use air entrained concrete on an interior slab with a steel trowel finish. You run the risk of delamination especially if you place in warm weather.

I would install a vapor barrier. There is very little downside other than the fact that finishers don't like them because they slow down the finish. It's always a good idea to limit moisture intrusion into interior spaces and a vapor barrier is a must if you ever want to apply a floor covering such as epoxy. It's cheap and you only get one chance to do it.

Finally, I wouldn't pin the slab to the foundation. You don't want to limit the slabs ability to shrink or you'll increase the likelihood of cracks.

Make sure you have a good solid base and let the slab 'float' on it. The fact that the existing slab is severely cracked makes me wonder about the existing base. You want at least 4" and preferably more well compacted granular material under your new slab.

Normally I'd say fiber is probably fine for a slab this size and recommend a saw cut control joint in each direction. With questions about the base, I'd opt for steel reinforcing to hold the slab together in case cracks re-appear. I'd still suggest a control joint in each direction.

Hope that helps answer your questions. Good luck with the new slab!

 

[Webosu11]

Thanks for the responses, I appreciate it.

This would be an early to mid-November poor (avg. high in the low to mid-50's, avg. low in the mid-30's). If I can't get it done then it'll wait until the Spring.

His reason for not using a vapor barrier is condensation will form on the interior of the garage windows thus leading to eventual rot of the surrounding sill, jam, etc. Is there any truth to this? I have some paint on the garage ceiling peeling at the moment, my thought was this is due to the lack of a current vapor barrier. I'm undecided on a floor covering at this time.


I'm in agreement on not pinning the slab to the foundation and will make sure whomever I go with does not do this.


I also wonder what the state of the current base is. In my opinion this more than likely has contributed to the cracking.

Saw cuts would be in each direction thus making 4 sections of the slab. His reasoning for not using steel reinforcement is the steel will expand when it rusts and lead to (more) cracking.


I never knew how much went into getting a solid cement floor!

 

[Lassen Forge]

The vapor barrier is to keep water from migrating from the ground to the shop floor. The condensation issues have to do not with the vapor barrier but your ventilation in the barn and your insulation or lack thereof. He may just be trying to talk you out of putting one in, because it's extra steps and does slow things down a bit, but I wouldn't not have one down there.

You may not have a lot of steel in the current slab (amazing how many people pour huge slabs - either sectional or monolithic - and put little or no steel in them). Yeah, it adds to the price, but the other hand is how long do you want that slab to last?

Sorry, but to me, his "logical explanations" are backwards and are, in my eyes, both huge red flags. If it were me, I'd think twice before hiring him.

 

[chamoisfive]

One must be nuts not to put a vapour barrier down. You only get one chance to do it, so do it 'cos it's relatively cheap.
Your contractor argument on the steel doesnt wash. I demolished a 45yr old concrete pad this week that had steel in it. Not a segment was rusted & it was as clean as the day it was installed. The emphasis being that it was clean & not rusted at installation.

 

[Webosu11]

Coming in to the project I was expecting a vapor barrier and steel so I was a bit surprised when he suggested not to do either. I'm lining up a few more quotes so we'll see what the others have to say.

 

[Jaguar Fan]

When the old slab is torn out, are you going to have the existing soil tested for its compaction percentage? And if necessary compact it more to get it up to spec?

I would absolutely put in the vapor barrier.

Have you considered a higher PSI concrete mix? Say, 8K?

I'm sort of a "belt AND suspenders" guy when it comes to things such as this. If it were me, I would specify mixed-in fibers AND suspended rebar.

 

[James-W]

I would say the price is right for what you are having done. What are planning on doing in the garage once you get a new floor? Is it just for parking your vehicles, or will it be more of a workshop?

 

[Webosu11]

I have not considered testing the existing soil for its compaction percentage, thanks for the suggestion. Is this something the contractor (or I) can do or would I need to hire some other trade for this? Based on the state of the existing floor my assumption coming into this was that the base would need some material and to be compacted.

I thought 4.5k PSI was sufficient for a garage slab (I think code around here is 4k). Is it necessary to go that high for a 2 car slab? We just use the space to park the vehicles and storage.

I don't have a problem paying for the right materials to do the job right. I want this to be the only time I have to do this at this house. I'm leaning toward fiber mesh and wire mesh at this point but still have a few more quotes to schedule.

 

[ConCretin]

Compaction could be the problem but it could also be improper materials or possibly water. You want a stable granular base that provides uniform support for the slab. Once the existing slab is removed, dig some test holes to see what you’ve got. If you find clay, silt, organics, etc, remove what’s there and replace with the proper materials. You could hire a local geotechnical firm to evaluate your base if you are unfamiliar with the requirements.

4000 psi is more than adequate for a garage slab. Frankly the suggestion to use 8000 psi concrete is silly. Your concrete supplier will look at you like you have three eyes if you even ask for it.

You can go with fiber and wire but before you spend the money, understand what they do for you. The fiber might delay early age shrinkage cracks to allow you time to relieve the tension with saw cut control joints. The wire ( if properly supported) will hold any cracks that occur together including the cracks in the bottom of your control joints. Neither will prevent cracks long term or make your slab stronger. If you have a good solid base, you could probably do without either on a slab your size.

 

[Retroman]

$10 to $13 a SF is what we charge for R&R of a slab.

 

[Webosu11]

Second quote is in:

Tear out/Haul away/Prep/Pour/finish/control joints/2 coats cure & seal
4" depth
6.5 Bag Mix (4500 PSI Grade Cement)
Air Entrainment (did not indicate what %)
5" Slump
Wire mesh

On par price wise with the first. Only real difference between the two quotes is the fiber vs wire reinforcement.

Once again he said a vapor barrier wasn't needed...

He indicated that the garage opening may not have an existing rat wall and he'd more or less require to poor one if that was the case. He also said they'd need to dig out about 6ft into the driveway for drainage reasons (I didn't quite follow this). Thoughts on that? There is a gap today on one side when the door is closed.

Soil in my area is heavy clay so it wouldn't surprise me to find that the base wasn't properly prepped in the first place.