Can we talk about Concrete?

[Tractor Seabee]

Yeah, I know we can.....

Here is the deal, I am about to go out to bid for concrete for my new shop. Of all the subjects I know the least amount about in terms of construction it is concrete and Youtube, while OK, is not great...

So the particulars. Right now I am aiming to just concrete the floor of the shop, no pad (unless my wallet thickens in the interum). So 45X72 is the floor size. We are in Mild Temperature, so probably not going to do any radiant (still undecided on this) and not sure if I am putting insulation under. It was suggested by the County Permit office, but not required.

I have no plans of heavy machinery but I would like to maybe buy an auto lift one day. So my plan was a 4" floor, and an area 6 inches thick around the spot I would put a future lift.

As for the floor itself, I am mulling over a central drain. I am also mulling over an in floor vacuum system for the wood shop. I will have a bathroom with a shower, as well as a clothes washer and sink so there will need to be drains for that. I do plan on putting in floor electric in the wood shop so I can hook up a saw in the center of the room...

So what do I need to ask guys, I kinda understand PSI, I kinda understand re-bar, I kinda understand fibre.

I know there are a lot of opinions, so I guess I can't wait to hear them.

This is a subject near and dear to my heart. I have written specifications, inspected, and supervised concrete work over my past career. Asking such a question in this type forum will provide a lot of chaff and you probably are not sure how to separate out the kernels of wheat. I am sitting here looking at 4 professional manuals on concrete work I have used throughout my career. All are available on Amazon I believe. For you I recommend "The Contractor's Guide to Quality Concrete Construction" by the American Society of Concrete Contractors. Another good manual is "Concrete Floors on Ground" by the Portland Cement Association. The American Concrete Institute is the source for all the building code requirements and they certify Inspectors. They do the bulk of testing on new procedures and materials and provide the guide specifications used by design engineers.

There are so many variables I would not try to specify your project on a forum such as this. Many old timers will disagree with the newer methodologies. Times and materials have changed a lot over the last 30 years. I used to attend the annual "World of Concrete" every year when engaged in the business. Every year they were dding and deleting methodology. Okie below says fiber does not replace rebar. No longer true for non-structural load bearing slabs on grade except heavy duty hard stands for dynamic loads. Construction Joints and Control joints (they are not the same) are the key along with a properly prepared sub-grade. Wire mesh is the stuff that is no longer in vogue. Nothing will solve a poor sub-grade, destined to fail, even with rebar. As an example going to 6" around a hoist does not buy anything. 4" is OK unless you are running tracked equipment on the floor. Then I recommend you get an engineered design. If you have a lot of heavy equipment compromise on going to 5". High strength (over 5000 PSI) is also a waste of $. Again the sub-grade is your basic support element.

Ron

 

[woodlandfarms]

Why are you thinking you'll need a central floor drain? Particularly if you have electric and a vacuum system in the floor, you're not likely to be hosing it down.

The shop has two parts, one side wood shop and the other auto and auto storage (45X24 wood shop and 45X 48 Auto / welding)

 

[woodlandfarms]

Thank you EVERYONE! I appreciate all the info I am getting. Ron, I am a type of person who loves the latest and greatest. I almost went to a concrete expo in Portland but was called out of town.

Anyway, More clarity. my shop has two sides, a smaller side for wood and a bigger side for auto / welding. I am walking away from the floor drain... I think you are right, a pitched floor would be more helpful.

Ground work is also a mystery. We have to dig down abit (a couple of feet) to level out the pad. I guess we then apply base rock and compact and then whatever comes on top of it.

One big thing is this, and advice I would love to seek from you as well. THe building is a Cold Formed steel building. Not new tecnology but one that is not employed a lot in buildings until the past 20 years or so. It was a lot cheaper than red, and much more fliexible than a pole barn. They have two foundation systems, one is a thickened edge slab, the other is using 24" concrete post (Piers) like a pole barn. One concrete guy is really recommending we go with this method as he an then pour the concrete inside a finished building. Our winters are very very wet, so that is a concern of his.

Thoughts?

 

[Streetcar]

I had a pro,40 years in concrete pour a similar slab. Mixture was 6 1/2 sack mix (about 4500 psi) 5敗lump, 1/2 shot of air and he used Super P which is really something to see. The slab is very smooth and very, very dense. 2 months old and already had 30000 # machine on it (raising trusses). Was saw cut with no panel more than 12x 12. So far looks fantastic. Slab has three perimeter #4 bars, otherwise not reinforced and is 5.5 thick.

superplasticer raises slump without adding water, making slab easier to place

 

[Streetcar]

Thank you EVERYONE! I appreciate all the info I am getting. Ron, I am a type of person who loves the latest and greatest. I almost went to a concrete expo in Portland but was called out of town.

Anyway, More clarity. my shop has two sides, a smaller side for wood and a bigger side for auto / welding. I am walking away from the floor drain... I think you are right, a pitched floor would be more helpful.

Ground work is also a mystery. We have to dig down abit (a couple of feet) to level out the pad. I guess we then apply base rock and compact and then whatever comes on top of it.

One big thing is this, and advice I would love to seek from you as well. THe building is a Cold Formed steel building. Not new tecnology but one that is not employed a lot in buildings until the past 20 years or so. It was a lot cheaper than red, and much more fliexible than a pole barn. They have two foundation systems, one is a thickened edge slab, the other is using 24" concrete post (Piers) like a pole barn. One concrete guy is really recommending we go with this method as he an then pour the concrete inside a finished building. Our winters are very very wet, so that is a concern of his.

Thoughts?

If slab guy wants to pour concrete inside the building let him. That way slab can be poured to building dimensions and door locations. This is less difficult than putting building on existing foundation

 

[cycle_gator]

superplasticer raises slump without adding water, making slab easier to place

That is for sure. 5” slump is almost self leveling, but without the water. I also used the mix for a stem wall on a14x14 lean to add on to the 30x50 main building. Came out really well. No voids anywhere with only some minimal form tapping. I will definitely be using that additive again unless I am trying to pour a slab that has slope. Then the additive really works against you.

 

[repete]

Since you haven't poured yet I'm curious what others think about a grease pit. If I had it to do over I'd consider one. That I'd have a drain, and bury plastic PVC or conduit over to it, a few feet from bottom for outlets, lights.
To me safer than a lift.

I had a pit in my first shop. I will not have one again due to the inability to work on tires and wheels, roll transmission jacks under a vehicle and the hazard of accidentally walking into the pit opening. It also was a great place for flammable vapors to collect even though I did put in a mechanical ventilation system under the slab and a drain pump system in the event of flooding. It simply did not work for me.

In my shop now I have a two post asymmetrical 9000# lift. When I poured my 32' x 60' shop floor I dug out two 24"x 24" by 24" (including 4" slab) holes where the upright posts would go. I used extra long anchor bolts. I had no confidence in a 4" or 6" slab although the manufacturer said it would work. I also failed to place a slope area at the large vehicle door opening to allow water to drain off the west facing door to the outside. Think plumbing for today as well as in the future. Tractor Seebee is probably right about the slab thickness for the lift but when my kids are lifting their 3/4 ton Duramax diesels on a Asymmetrical lift the extra $50 of concrete is just peace of mind...

Another thing I did, since I poured within an 18" stem wall foundation, was to seal the large door opening from the outside (other doors were step down to the slab) and flood the area with water for a couple weeks after the final trawling. I used a stock tank float to maintain a couple inches of water around the clock.

Plan two doors for egress in case of fire so you can run in either direction and not be trapped.

By all means, research your contractor and be sure the contractor has the same employees working for them as were there when doing the slab you are looking at.

 

[Tractor Seabee]

Thank you EVERYONE! I appreciate all the info I am getting. Ron, I am a type of person who loves the latest and greatest. I almost went to a concrete expo in Portland but was called out of town.

Anyway, More clarity. my shop has two sides, a smaller side for wood and a bigger side for auto / welding. I am walking away from the floor drain... I think you are right, a pitched floor would be more helpful.

Ground work is also a mystery. We have to dig down abit (a couple of feet) to level out the pad. I guess we then apply base rock and compact and then whatever comes on top of it.

One big thing is this, and advice I would love to seek from you as well. THe building is a Cold Formed steel building. Not new tecnology but one that is not employed a lot in buildings until the past 20 years or so. It was a lot cheaper than red, and much more fliexible than a pole barn. They have two foundation systems, one is a thickened edge slab, the other is using 24" concrete post (Piers) like a pole barn. One concrete guy is really recommending we go with this method as he an then pour the concrete inside a finished building. Our winters are very very wet, so that is a concern of his.

Thoughts?

Ultra,

Is this in LA or WA? What is the type and weight of the equipment in and out of the shop. Do you have a site and foundation design? Soils investigation? The generic foundations by the building manufacturer have to be site adapted unless you provide the information they require for design by CA or WA licensed engineer. I would go with the post piers and place the concrete under cover, solves some of the variables. Make a construction joint around the piers. If you are serious about a lift; choose one now and get the install instructions. Plan the foundation into the slab. Key on the lift foundation is the point loads. Set those areas off with a construction joint all around. Get references on the concrete contractor. Certification by ACI is a big plus. Get the base preparations and concrete placements supervised and inspected by an ACI certified independent inspector, money well spent. As you answer my questions it will trigger follow on questions and recommendations.

Ron

 

[ovrszd]

In regards to floor insulation. It's not cheap as someone mentioned. 2" will cost $24-ish per sheet. You need 102.

If you are gonna heat the building insulate the floor.

In regards to radiant floor heat. It will cost you an additional $1,500 to buy the pipe/fittings and pay to have it installed. Whether you spend the additional $3,000 to make it heat is up to you.

You only get one chance to have floor heat.

The added cost of insulation and piping is insignificant when compared to the total cost of construction. For example, what's your estimated total cost for this building?

 

[Jchonline]

I would much rather have a shop slab lightly sloped to the outside doors than have a central drain. Shops accumulate a lot of trash that will completely clog a floor drain (especially a woodworking shop). I would sure hate the job of keeping them opened. I can just pressure wash my shop floor and push the water out the open garage doors. The floor dries fairly quickly after such treatment.

Totally agree. I open the doors and use the blower to blow bio mass out, and let the fluid air dry. I can't imagine what a drain in a garage would get clogged with!

Also on the vacuum system, there are lots of great videos on Youtube.

Check out April Wilkerson or Jay Bates and just search for their workshop vacuum install videos. None of them are in the floor.