Questions on Garage/Workshop Slab

[fperra]

I've hires a contractor who specializes in garage and workshop construction to build a 52'X30' garage/workshop. I live in the Tacoma, WA area and our Winters are mild and our Summers are cool. I assume this moderate temperature variation has an effect on the concrete specs, but I am no expert so I would like some opinions on a few questions. The garage will be a two car unit with separate doors and measure 28' wide by 30' deep. The attached workshop is 24' wide by 30' deep. The garage will have both a 2 post and 4 post lift. The flooring will be tuff-seal or Armor PVC tiles.

The contract currently calls for 5" thick, 5 sack 3000 psi mix of concrete with fibermesh and Rehomix 235 Vapor Retarder. No rebar or wire mesh. There is re-bar in the perimeter footing. So, with that given, should I

1. Increase the slab thickness to 6"?
2. Change the mix to 6 sack 4000 psi?
3. Add 10/10 wire mesh reinforcement (a $1930 option)?
4. Am I missing anything?

Any help is appreciated.

 

[sstruckguy]

I'm going to think out loud here, but there are a few things that I would seriously consider:

1) Being located in the northwest, isn't the water table fairly high?

With that being said, I would want to make sure that there was NO chance of the slab cracking or that the mix might not hold up to the lift mounting/

2) Why is it so costly to lay down the wire mesh?

That is an expected procedure here and isn't an "add on" charge.

3) If you haven't thought about a water supply or a floor drain, you won't be sorry adding either one.

Melting snow from a vehicle or even the always possible "wet" floor clean, will make things go smoother with these additions.

Thats about all that comes to mind for now.

Good luck with your build!!

p.s make sure you take plenty of pics and start a build thread. With all the experiance on this board, you will get usefull suggestions all the way through it

 

[fperra]

When I first decided to do this project, one of the first things I wanted was a drain in the garage so I could wash the cars in the Winter. But the contractor gave me the price and I said forget it. The building code here requires an oil/water seperator for a drain in the garage. Don't ask me why, since a million cars drive on the road and the storm drains dont have this rquirement. Go figure?

 

[Brambles]

I'd say Yes to all

6"
4000 psi
and reinforcement.

I used boatloads of #4 (1/2") rebar and 4600 psi concrete(32mpa) IMO you can never go overboard on a concrete slab.

That being said, if they pooch the compaction then no matter what you put in the floor your not gonna be happy with the results

 

[fperra]

Thanks for the info. Anyone else?

 

[swharris]

What if you put door wide drains "outside" (just outside)the building and slope the floor towards the doors? Would they still consider the drains "in" the garage??

 

[Kevin54]

I would forget the wire mesh and go with rebar instead.

 

[Challenger RT]

I would spec the slab for the 2 post lift. I have a Mohawk A7 and the minimum slab requirements are 4 1/2" with 4000psi with #6 rebar 12"apart. If money is an issue maybe just do the garage slab this way.

 

[pimp-boy]

Hi Challenger RT, do you have pics of your A7 setup? For $600 more, would you recommend going to the System IA?

I'm in the process of building my garage with #5 rebar, 4000PSI with a 5" depth.

Thanks.

 

[nehog]

First, there is no way that you can be 100% sure it won't crack.

Second, go rebar... Fiber mesh (as my contractor stated) is not nearly as good.

 

[DIC]

I would use plenty of rebar.... post pics of the build......
Thats a nice size...........