My landlord has given me permission to pour a slab for a machine shop next to mmy (single-wide) trailer abode.

The walls and roof will be a decent quality "Sea-Land" style shipping container with well insulated walls, lots of lights and an adequate heating/cooling system to keep the internal temperature stable @ 72 degrees.

My question deals with the floor. Is the most stable arrangement to pour a single 8" slab with lots of re-bar over a thick gravel pad, or to have individual, isolated "piers" under the lathe, mill and tool post/surface ginder.

Also, with piers I could use something like 55 gallon drums or cut down sections of the tubes that sheet steel comes rolled around to run some concrete and re-bar deeper into the ground as a "sea anchor". We don't get frost heaving at the elevation where the shop is. The soil is reasonable well drained. We get 12-14" of rainfall per year (semi-arid).

Thanks for your input. I don't have much money, but I don't want to be levelling machines before every job either.

LD

Lawndart, Have you heard of the Alaska Pad? This is a pad where the outer edge is exaggerated to like tripple depth of the pad thickness if I am not to far off. standard reinforcement and good base preparation are always a must. Seek good advice form a concrete specialist. I really don't know Jack... and he doesn't do concrete anyway!

typically a 4" gravel bed, some plastic and then 2" of sand on top of the gravel will provide adequate drainage---as for piers unless you're afraid the slab is going to slip down a slope or shift locations or you're putting an ungodly amount of weight in certain areas you don't need them with an 8" slab especially if you double up the rebar(2 mats separated by a couple of inches vs 1 mat)--of course with piers at designated areas you can decrease the slab to probably 4" unless you're driving tanks or such on it ---#4 or #5 rebar at 16" centers each way or less if you desire can withstand a lot of force and you can get grade 60 rebar vs grade 40--also if the area is bigger than 10' x 10' make sure you put some deep grooves in the slab to control cracking--the more grooves the better of course, but you don't need to go nuts on them--just divide the slab up into equal portions no more than 10' in any direction---you can also get custom strength concrete--2500psi is standard for most foundations and it's no problem to up that to 3000 psi, but you should verify with the supplier to be sure they don't charge an arm and a leg for the increase---how big are you talking and what are putting in there--lathe(s) and ??? and how much do the weigh??...a thickened outer edge isn't a bad idea as stated above also---usually 8"-12" wide and 12" deep will work unless you're building more than a one story structure for extreme use...chris

I have to re-check, but I believe the dimension is about 10'x30'.

The grinder is only going to be 800# full up. The mill will be 1,800 - 2,200; the lathe as heavy as I can afford.

No slope to worry about.

I guess I'm still paranoid after trying to work with chemistry instruments in a shaky science building in college.

LD

Hey Doctor lawndart, I am diagnosing you with a bad case of overkillingitis. Just pour a slab 4-6 inches thick renforced with steel. I would make a footing around the edges. That is around the perimeter by the forms dig a little deeper. So the concrete is say 8-12 inches on the edge and the bulk of the pad is the 4-6 inches.

There has got to be a concrete contrator in town that you can bend an elbow with and squeeze a little info out of. I don't think you will need to put in expansion joints. That is you can make one continuous pour. The levelness will all depend on your ability to set your form and finish your concrete.

are you going to bolt the equipment down??? you have some options if you're doing so:

pour a thick slab-- 6-8"

layout where the pc of equipment will be bolted down and make the slab thicker in those areas only--

el caballero's suggestion sounds fine for what you need---a 4" slab with #4 rebar on 16-18" centers each way and a thickened perimeter with one pc of rebar in the bottom of the trench(2" above earth) should do you fine---a 5 or 6" slab is up to you--remember that lumber comes in 3.5", 5.5" and 7.5"(unless you get rough lumber) so if you want true dimensions the forms need to be raised above the ground a .5" --this creates no problems---you can preplace the bolts for your equipment also prior to pouring the concrete---anchor bolts come in 1/2", 5/8", and 3/4" diameters and different lengths, but you will need to thicken the areas where you want them because they don't come short enough for 4" slab ---you can also use bolts with washers or all thread with a nut/washer/nut imbedded also---good luck---chris

Hello Lawndart,
Are you cutting off the floors on the containers? I would think bolting a lathe to the floor would make it easy to twist. Just use the leveling legs. Most gunsmith jobs are light work. Altough fixing equipment for the local ranch owner will make it jump around.
John

Having poured more than one sidewalk, I believe 4" of steel reinforced concrete will be adequate. Where you'll need help is with the form work. If the floor isn't level and true under your lathe, you're wasting time and money. I would also give some thought to a "honey pit" for the floor drain you'll need. Design it wide enough to be cleaned with common garden tools, and incorperate some kind of grease trap. A plastic 50 gallon "Round Up" barrel would work fine.

quote:

Originally posted by buckshot:
Having poured more than one sidewalk, I believe 4" of steel reinforced concrete will be adequate.

Absolutely. And you don't have to bolt down a lathe and a mill.

Shipping containers are really great for workshops. I had a project in the middle of no-where in North Africa and we made a whole mini-city out of conexes. All of the workshops were made out of them and we just set them on six piers about 18" square and 2.5'feet deep. The floors themselves are designed to stack up to 10 high so no need of a full slab underneath. Set up off the ground 4" or so for air circulation underneath. We poured a ramp on the door end and if we wanted more space, we would set them 20 apart with a 4 inch slab between and had pre-fabbed roof supports made and then roofing tin over that. Had a fully functional shops set up in a matter of days. After that, the ones used as offices were insulated and panel with an AC unit in it a viola. Good luck with your workshop!

LD, 3500 PSI fibermesh, 4" with a turndown slab will be fine. IF you want to be a little anal put some 4" square chicken wire and plastic under that on the ground. The key thing is knowing that the dirt it sits on is good. As someone else mentioned, if the ground is questionable, a gravel pad does wonders from a stability standpoint, all our geotech engineers will tell you what a great job 57 stone does of 'distributing' a load.
Don't be putting a 50 gallon anything in the ground or slab if you want to pick it up when it's full. You don't want to be drilling into any re-bar if bolting something to the floor is a consideration.

Think about your finish, a machine finish with an acid stain is pretty attractive and VERY durable, albeit a little slick, especially if it gets wet at all--include wet soled boots in that assessment.....

If you want a genuine engineering spec PM me.

Regards--Don

OK for long term results of floors.

Dad's shop is a 4 inch slab, on gravel, you could feel the floor move when heavy machines were being used.

My old shop floor is a avg of 6" thick with fibermesh. No problem with the lathes and mills.

The next floor I made 8" thick with fibermesh as I knew I was going to put some big machines on it, again no problem.

The newest we went 6" thick with rebar, on a gravel bed. This one has the punch presses on it. As it is only two years old it is a little early to tell but the 35 ton punch press so far is OK on it.

Jim Wisner
Custom Metalsmith

Is this slab going to be removed whenever you move? Are you planning on doing a -lot- of machine work or mostly hand work type stuff? How long do you plan to live there, 5 years, 15 years? In addition to the slab, will you be required to remove the container when you leave?

I'd be tempted to maybe pour some footings for the container to sit on, or maybe talk to the dept of public works and see if there are any broken sidewalk sections they are planning on removing and use those. Then I'd set the container on them and put down a couple layers of 1/2 ply except for the last 4 or so feet. That part I'd cut out and set a couple cardboard tube forms into the ground, frame it in, and pour it flush with the rest of the floor. Then you'll have concrete where you need it and it'll be a heck of a lot easier to move out of there. The wood is also easier on my feet than concrete is.

Of course, the slab doesn't have to be at the back, I imagine a 2.5X10 strip on the side might be better but you get the idea.

Lawndart, consult a local architect. Are you going to cut the floors out of those shipping containers?

If your going to spend the money on a concrete foundation why would you want to set shipping container on it. Have you looked into steel building kits? Maybe you should spend your money on buying the land first so you arent waisting your money developing someone elses property? Realy!

I can't think of any reason whatsoever why 4" would not fully support whatever you are going to place in your workshop. Often people underestimate the strength of properly placed reinforced concrete.

In your situation you should be well served by a 3.5" to 4" thick slab reinforced by 6"x6" reinforcing mesh which can be had from your local lumber shed or home depot. Form up w/ 1x4s, grade the dirt/gravel, place a sheet of visqueen, install your mesh, place plain jain 3000 psi concrete and pull your mesh up slightly while the 'crete is wet to get it alittle off of the visqueen. Finish it, let it set for at least a couple of weeks (28 days gives full strength) and place your building. I wouldn't even put footers in the slab if it's going to be a storage shell like you said as there shouldn't be very much weight on the walls.

I figured a tiny job the other day for a 3 ton hot tub pad (full weight) and it only consisted of a 4" reinforced pad of about 12'x12' square or so. I wouldn't think your equipment would be nearly that heavy.

Good Luck w/ your new shop.

Reloader

First off, if the project is subject to any codes you will have to pour a slab that has a footing that extends below the frost line. This could be a thickened edge slab also known as a mono-slab. Then everywhere you have equipment setting you can do the same concept under the bearing points of the equipment. Just thicken the areas where the legs of the equipment will set. This area should be around 12 inches thick to support the weight and give you something for the anchors to tie into. Usually these thickened areas are around 12 inches wide but could be wider. Throw a couple pieces of 1/2" rebar in the thickened areas and you are in like Flint. I've driven a 250 ton crane on a five inch slab so you can make your own judgement there but I will tell you an 8" slab is overkill. 4 to 5 inches is plenty strong enough. Put you steel on a 12 to 18 inch layout and you are good to go. Use a vapor barrier for moisture control and keep the slab wet until you get a good cure. Usually about 5 days until you can drive on it.

There was a 5 acre property outside of sandpoint with a 2000 sqft garage already built with a concrete foundation built for a machine shop. It had a rough graded pad for a house, a out building with a battery genavator already intsalled , well , power etc. $99,000

If you know your layout you may also want to consider placing electrical conduit in the floor to minimize cords and cables at floor level or above. Same goes for any plumbing you may be considering.

If there is any chance of rain/water getting in and on the floor then you may also want to consider keeping the floor center high with a minor slope to the edges.

Thank you all for the input.

I have the shipping containers already, so the wall and roof are free.

Architects have nice offices. It costs a lot of money just so they can tell me how to spend more of mine.

Code? code? We don't need no steenkin' code. Only the good lord knows how many County inspectors in Idaho have ended up as catfish food in the Snake river.

My landlord lets Lois and I live here for free. If we ever move, it means we have made enough money to do so. I will leave the slab and container if he wants them.

One nice thing about a concrete floor is I can put down a polyurethane finish in a light gray. Easier to find stuff when I drop it.

I have to plan on making heavy stuff from time to time. Making a part for a rancher might equate to hunting access, a load of feed or some beef.

I'll make a rebar map, and put it on the floor after the pour to avoid trying to drill through it to place an expansion bolt.

Making the pad thicker where the machines will go makes sense.

One of the few talents I have is the ability to make level forms.

Having spilled every thing from milk to the beans in my life; a little slope to a grease trough to a trap makes sense.

Too bad I'm not still married; what a golden opportunity pouring a new lab could be.

Thanks again guys, this is very good info for me to mull over.

LD

Lawndart, on a project like this, it is ALWAYS cheaper to over-engineer than to engineer.

When I put up my last building, the outfit I bought the greenhouse from wanted $1,500 to calculate the proper anchorage for our site. I chose to upgrade to the heaviest method for $150.

Put things on a good gravel bed, a good footing around the edge, and go a little deeper where you think you might need it. I'd never put any more plumbing or electric in the floor than I needed. Dropcords from the ceiling are far more versatile.

Don't forget to cut expansion joints! The rebar or mesh needs to be far enough down to allow for that.

As far as fibermesh -- don't waste your money. JMO, Dutch.

I do tend to over-engineer.

I'll let you know when it is done. If you have the misfortune to have to visit the Boise area I'll show it off.

The local construction boom is falling off. I'll see if I can get some concrete delivered this fall, insulate the slab and let it cure over the winter.

LD

JC,
ask a local plant engineer about "fiber crete".. stainless steel slivers in the mix.

jeffe

LD,
Anyone can design something "hell for stout" but it takes an engineer to design it so it is just on the verge of falling down.

Dammit John, you sure seem to get some of this shit going real strong. ESPECIALLY if you can get Cusotomstox to chime in.

Chic,

Spoken like a true engineer

I agree with those suggesting stouter 6" slabs. While a 4" slab can take the weight, the issue is having a stiff slab so the lathe won't vibrate while doing heavier work. Just as you want a heavy lathe, you also want a solid foundation to mount it to. I'd want 6" minimum, or if you know exactly where the lathe and mill will go, you could make them 8" thick about a 1' around their bases, and go 4" for the rest of the slab.

There is no such thing as a lathe that is too stiff or mounted on too solid of a slab.

quote:

it takes an engineer to design it so it is just on the verge of falling down.

He, he, he, he, he.

A high school classmate became a nuke engineer in Bremerton, Washington. He described Navy testing procedures thusly:

"We test it until it breaks, fix it and then resume testing."

LD

quote:

Chic,

Spoken like a true engineer

I agree with those suggesting stouter 6" slabs. While a 4" slab can take the weight, the issue is having a stiff slab so the lathe won't vibrate while doing heavier work. Just as you want a heavy lathe, you also want a solid foundation to mount it to. I'd want 6" minimum, or if you know exactly where the lathe and mill will go, you could make them 8" thick about a 1' around their bases, and go 4" for the rest of the slab.

There is no such thing as a lathe that is too stiff or mounted on too solid of a slab.

I talked with my landlord today (he is a retired commercial builder). We decided to put in a pole structure with just what you suggested. 4" slab except an 8" deep section along the side where all the machines will be, and a deeper pour all around the edges.

Before the machines go in we'll snap chalk lines over all the pieces of Re-bar.

A concrete contractor is coming by next week and we'll start figuring the damages.

Then off to the banker. We have been paying the note on the clinic down in lieu of owning a house or pesentable vehicle, so he will likely go for this.

LD

quote:

Dammit John, you sure seem to get some of this shit going real strong. ESPECIALLY if you can get Cusotomstox to chime in.

You betcha.

LD

quote:

JC,
ask a local plant engineer about "fiber crete".. stainless steel slivers in the mix.

jeffe

I wonder how many packets of Brownell's "Steel Bed" it would take ??

LD

quote:

Originally posted by lawndart:

quote:

JC,
ask a local plant engineer about "fiber crete".. stainless steel slivers in the mix.

jeffe

I wonder how many packets of Brownell's "Steel Bed" it would take ??

LD

DANG!!!
that's pretty durn funny....

remember, I am not a structural engineer... but I recall the chemical plant engineers mixing SS with the concrete to pour the pads and stands for big ole compressors and pumps, and then keeping wet burlap on them for 2 weeks or so..

they did the same thing when they poured the slab for our (i was working in a plant as an IT manager) new lab... IRC, 12,500sqft... and if you know anything about houston, the soil MOVES here, destroying foundations...

they used the same fiber, and came over it with a FLOOR SANDER (well, a small army of floor sanders) just like you use on a workover of wooden floors...

The plant maint. manager, who was my best friend there, tried to 'splain it to me ... said that there is so buck fiber in the concrete that it's like the entire slab interlocks, and when the moves away .. which it will do here even under an engineered slab, the fibers keep the slab from cracking.

and the sanding was to get the fibers that were sticking up ground off!!


probably overkill, but HELL for stout

jeffe

I think you should just go w/ a post tensioned job

Heck, put some 4' footers around the exterior, a few more across where the machines will go, add your visqueen, and drop your sleaved cables in. Place some 6000 PSI Crete w/ fiber added. Heck, when you move out, they can place a water tower on it

Reloader