New Floor

[jlames]

We've a dirt floor in our 30X40 shop. The previous owners poured perimeter footing for the structure but never the slab so, getting up on retirement time, I'm building the shop for metal working hobbies and jobs around the ranch and am pouring a floor. So, with that said, what kind of accommodations should I make to the area supporting the anvil? Nothing mammoth; a 3-burner forge I'm figuring and 165 or 200 lb anvil for, again, mostly hobby work?

[DSW]

Hello and welcome. Take a minute and add your location to your profile so we always know where you are at. Lots of guys from different parts of the world here and it helps if we know about where you are when answering some questions.

 

 

As far as the floor, a good solid packed dirt floor will be fine. Many prefer a dirt floor over concrete when working for hours as it's easier on the back. Concrete has it's advantages as well, so you need to decide 1st exactly how you plan to use your shop. Some split the difference and use dirt in part of the shop, and concrete in other areas where they want to be able to easily roll carts and stuff.

 

Biggest thing I'd suggest if you go "dirt" is to make sure you have good drainage and don't have water issues. Mud is no fun, and under cover, things can take forever to dry out. There are a couple of solutions to this issue, but we'd need more info on your situation to make good suggestions.

[Steve Shimanek]

I think 6 inches should be good, but what if you get a power hammer in the future?

[DSW]

 but what if you get a power hammer in the future?

 

 

Take a saw to the floor and cut out the area where you want the hammer and dig and pour your footing. Not really a big deal unless you ran radiant heat in the concrete floor.

 

4" of concrete would be enough if the slab is done right and the subsoil is well compacted and won't settle. 6" would be better if you plan on a lot of heavy things like fork lifts or vehicle lifts. We usually tried to pour 6" slabs given the choice, simply because in some cases we were dealing with new construction and it might not be possible to get the soil as compacted as we might like without digging up the whole area. The thicker floor would help bridge "soft" areas and prevent the floor from major cracks.

 

 

Note that concrete WILL crack. Concrete shrinks 5/8" in 100' as it cures if I remember right. we never troweled in control joints, but came back and saw cut the joints in the next day. That allowed up to have more control over where we wanted the cracks to occur, and made them "invisible" as the floor will crack at the weak point of the cut if done correctly 90% of the time. Also saw cuts are smoother if you roll things around. We'd also always use fiber mesh in our crete to help with limiting cracks, but only use wire if the pour was 6" or thicker. Then we'd use rigid mats on chairs so we had control over exactly where the wire was. The idea wire in a slab will "prevent" cracks is BS. All it does usually the way most guys use it is hold things together after it cracks.

[arftist]

Good points. Dirt is the best for standing on, and is easy to clean to boot. Tools do get lost in dirt though, it is unavoidable. 

 

If you do go with concrete, pour a full 6" reinforced slab. Use the truck garage code. You will never regret having a six inch thick slab, and such will support most air hammers. Should you end up with an ancient hard hitting mechanical hammer you can always spread the force with a thick steel plate. If you become professional smith you can always cut a hole in the floor and add a sufficiently sized foundation cube for your hammer. Your anvil needs no special prep under the floor, though I tend to bolt a thick steel plate to the underside of my anvil stumps. (helps them in the dirt or on concrete). 

[ThomasPowers]

Will you be burying the anvil stump several feet in the ground?  If so box out a place for it with no concrete.  Will your anvil's support just be resting on the concrete?  Then nothing special is required for the anvil.

 

My shop is 20x60 and I have half concrete and half dirt, as mentioned dirt is easier on the body, also harder to move equipment on and is "dirtier"  So my dirt shop is for forging, grinding, welding and my clean shop is for finish work machine tools, etc.  There is even a 10'x10' roll up door between the halves...Of course out here in the desert I don't have moisture issues save for the lack of it!

[Randy Bill]

Congrats to using the term concrete! First rule: run away from any contractor who can "pour cement". Portland cement is an ingredient in concrete and concrete is placed, not poured. Investing in concrete is not to be taken lightly; it is extremely difficult to find a contractor who knows the science of concrete and can provide the owner with a good value. The vast majority of concrete is incorrectly done and a terrible waste of money for most. Correctly done, concrete will NEVER crack. Proper base preparation and proper curing of the placement are the most often overlooked. Good info is available, this isn't a place for uncle Ed's reflections on his "help with the neighbor's cement" (worse if pronounced see-ment). Stick with dirt if at all possible and buy more tools! 

(In a previous life I was employed with the Bureau of Reclamation in materials testing (yup, concrete) and the job was to protect the taxpayer's investment in concrete.)

[beammeupscotty]

For me soil and wood chips are the ideal shop floor but I also have a section with a floor for storing materials and equipment.  With wood in the mix it is easy to find dropped hot work by the smoke but dropping and finding tools or small stuff can be a problem.

[patrick]

There are some advantages a concrete floor, namely the ability to easily move things around on it. The anvil does not need anything special for support. Power hammers and other large tools will as already noted. When I moved into a building like your, I poured an 8" thick floor so that I could easily use drop in anchors for things like post vices. If I hadn't been in such a time crunch I would have made T slots from channel iron and laid several of those parellel to allow even greater flexibility in anchoring things. I have a couple of friends with this type of arrangement and it offers an extremely rigid anchor point that is flush with the floor. If you set up several of these 8 or 10 feet long you really have a great many options to rearrange things if needed.

[matto]

I do not agree with an above post. My family has been pouring cement for 60 years! The poured cement mix dries and sets in to concrete. There are also only two guaranties with concrete one is that as it ages it will always be getting harder, and the second is that it will crack! There are to many variables involved to say it will never crack. Yes doing test samples in a lab I can agree it will not crack if done right. But in the real world we all live in it will, we as concrete professionals try to control were it will crack by using control joints and cut. We also use rebar instead of fiber mesh or wire mats.

As for the question in the post a 6" slab will be mor than enough. you will not have any problems with your anvil. as Thomas has stated if you do not want to move your anvil in the future form out a 2 foot by 2 foot square and then pour your slab, after that you can dig a hole in your boxed area and set your anvil stump. if you pre set your stump then make sure the corners are well rounded if you have sharp corners, that is where you will get a crack. the other thing you can do is wrap the stump with expansion joint or foam or rubber to allow for a buffer between the concrete and the stump. they will expand and contract at different rates and that force generated between them will cause a crack at the weakest point. (usually a sharp corner). or the other option is to make a stand that you can bolt down to the floor. which will make the anvil more mobile. or if you are just doing lite work you can just use a heavy stump or stand and then you can role or two wheel dolly it anywhere.

[bikecopXXX]

dont forget the gozintas!