How much concrete can you mix by hand?

As a first step in organizing my garage, I am planning on adding a "shed" area attached to the back of my garage. My plan is to build a 5 foot by 15 foot addition to the back of the garage with doors to the outside, where I can keep my lawnmower, yard stuff, etc. I would like to pour a concrete pad for this, tied in to the foundation of the garage. Being 75 square feet of concrete, 3 to 4 inches thick, could I mix this by hand? Would I need to rent a mixer or could I do bags? This seems too small an amount to have a concrete truck deliver, or am I wrong?

It's about 23 cubic feet total for 5'x15'x4".
A yard is 27 cubic feet so you are pretty close to what the concrete companies will deliver. Not sure the price difference in bags vs. delivery but time and labor should factor in too. I think the 5x15 would be hard to do in a single pour mixing bags, single pour is easy for the truck.

call and get prices on delivery and price out bags of concrete and go from there.

this would be just under a yard of concrete.... I would see if you can get a left over load of concrete from an over run... you have to be careful about the concrete starting to set up. I would recommend calling the concrete readimix place and ask them for a price. Concrete is usually about $80 to $100 per yard.... it might not be worth your hassle. For sure, I would use a mixer if you are going to do it by hand.... I don't remember if a 60 lb bag of premixed concrete is 0.5 cubic foot or not... if so, you would need about 60 bags.....

You are best off either renting a mixer or having a truck deliver it to the site. Personally, I would choose the truck. A quick look onhttp://www.concretenetwork.com/concrete/howmuch/calculator.htm approx 1 cubic yard of concrete, which amounts to 42 80lb bags!! Cement truck delivery may pay for itself in time and effort savings.

For the shed add-on, you may also want to consider a wood floor (assuming you have it off the ground just enough to prevent rot). There's a bunch of ways you could do this inexpensively that would last quite a long time and be plenty strong for lawn mowers etc.

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Do you have in your area one of those trucks that show up and mix what you need on site, usually half to 4 yds. ? Or a small rental yard that has the ready mix trailers full of concrete?
I would vote for delivery , fast, clean, no problems.

Dunno about finding places that will bring you a yard.
Around here, with three places that have trucks, they all have a minimum of 5 yards. They won't fire a truck up for less.

.8 yard really does seem more in the by-hand size.

Mind you, the truck is nice...If they can pull right up next to the job.

I am looking at pads beside my new shop. Minimum is five yards, with pumper which is 250 minimum.
So to pour in my backyard is 650-750 to have a truck bring it, or 150 to buy it and mix it myself. By myself I mean, draft some friends while I ‘supervise’.


With the pricing structure 5 yards delivered or 1 yard is the same price here. And while I can easily get a class A motorhome back there, they don’t want to drive in the truck because of the sharp turns, soft sand and not being sure they can clear all wires, trees, etc.

Without knowing your location, I'm thinking that need more than a simple 4" thick slab in order to tie into the existing garage foundation and still meet code. At a minimum I would think you're going to need a 12" deep turned down edge on the slab. That's going to add about another 1/2 yard. If you are in a cold location requiring footings and frost walls, you're looking at a few yards. For less than 2 yards, I would rent a small tow behind mixer. You have too much to do by hand from bagged mix and still be able to get consistent results without creating cold joints in the concrete.

The other option is to see if anyone in your area has small batch concrete trucks. Basically, It's a small concrete plant on wheels - holds enough sand, cement, stone, and water to mix 4 or 5 yards to whatever quantity you need as you need it. I want to say that the material ends up a little more expensive per yard but you only pay for what you use which makes it good for sheds, fences, basketball hoops, etc. Something to look into.

I agree with rieferman. Why not anchor it on a concrete pillar set every 5 feet, with the floor (like a deck) built on that base? Concrete makes sense if you're going to park a 3000# car in it, but not so much for lawn gear.

Some stuff for you to consider

1 bag of mix one gallon of water x 43 figure an easy 8 min average to mix ( you will get tired and slow down) this will take up the better part of 6 hours. the first 1/4 of you mixes will be setting up by the time you finish. this will cause failure later on down the road.

A rented mixer will half or one third the time of by hand. ( depending on experience)

Having a yard delivered will take less then an hour and leave plenty of time to float it properly.

If you get a yard delivered my suggestion is to get a 3 slump mix , it will be stiff but quite workable do not doddle around have every thing ready to go well before the truck shows up. ( this includes forms built , ground prepped, tools ready, payment ready) once pored you will bust you but for about 2 hours then wait for it to settle then you will be back to working it to get the finish you desire.

Our area is 3 yds. minimum for delivery. No larger than what you want, you may want to rent a mixer and DIY. On the other hand, Family Handyman had an article on doing a bump out in a garage. I don't know if I still have the magazine or not, but if I can find it you are more than welcome to it. I think it was from sometime early last year? It was pretty straight forward and if I remember correctly it had a wood floor.

Thanks for all the info. I will call around and find out the minimum amount for delivery. I will also check and see if there are small batch concrete trucks for my area (NW suburb of Chicago). If you have an article on bumping out the garage, I would definitely be interested. Sounds like it'll either be delivered or rent-a-mixer, bags are definitely out. Again, great advice and info.!

Kevin54 said:

Our area is 3 yds. minimum for delivery. No larger than what you want, you may want to rent a mixer and DIY. On the other hand, Family Handyman had an article on doing a bump out in a garage. I don't know if I still have the magazine or not, but if I can find it you are more than welcome to it. I think it was from sometime early last year? It was pretty straight forward and if I remember correctly it had a wood floor.

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I know the article you're talking about. It was from 3 or 4 years ago. I might have the article at home somewhere but I tried looking it up on their website only to learn that that site ***** - slow (even on my office's high speed line) and hard to navigate - and that it doesn't seem to be there.

Chuckster815 said:

Thanks for all the info. I will call around and find out the minimum amount for delivery. I will also check and see if there are small batch concrete trucks for my area (NW suburb of Chicago). If you have an article on bumping out the garage, I would definitely be interested. Sounds like it'll either be delivered or rent-a-mixer, bags are definitely out. Again, great advice and info.!

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Being in Northern IL, you're definitely going to be looking at a full footing and frost wall to 42 or 48" below grade or the system that is in the article that's mentioned above. Basically, they sunk PT 4x4 posts at the corners, bolted a ledger to the side of the foundation and built a deck with PT plywood as the surface setting the plywood flush with the existing slab. I don't remember how they vented or insulated that floor though. Since you probably have finished grade a few inches below the top of your existing foundation, that could be a problem.

I mixed 31, 80 lb bags of Sakrete this weekend. I own a mixer. I was filling concrete blocks so they'd be solid instead of hollow

For the labor savings I would purchase whatever the minimum is, you can always find someplace to put a little more sidewalk or slab to use up the extra. If it doesn't take the minimum by the time you have footings, if you need 48" deep footings as someone posted you will be close to the minimum already.

Do you have a place around that will mix it and pour it into a cart and you can haul it? They usually have 1 and 1.5 yard carts. When I lived in Baltimore ABC rental did this and I used them a lot. Made everything so much easier!!! Go fill it up, pour, trowel, spray out the cart and take it back...

Why tie it in to anything? Pour your pad and let it float.

Back in 1991, I poured a 4" pad (15 FT wide) next to an existing garage then later built a 5 X 22 FT lean to (for my mowers, other garden junk, etc.) on top of it and hung it on the garage. Hasn't moved, and your weather is similar to ours. Have another lean to around back about the same size, except about 4 FT high, vs the other that is about 7Ft. fitting under the eave. This one sits on a 1 FT. floating square "wall" that I poured against the rear foundation, and the front sits on floating deck blocks. A wooden floor fills the space just above ground level. Around here you can legally do that kind of shed stuff without a permit if under 100 SQ. FT.

Back in the early eighties at our previous place, I poured a 4" concrete driveway all mixed by hand in a homemade mixer. Poured strips about 4 FT wide and only worked at it when I had the time. You don't have to pour it all at once. You automatically get your "relief joints" as you go. Just looked at it last week and it is good as the day I poured it. Mix was 1 concrete, 2-3 sand, 3 stone. Poured a bunch of retaining walls there also (same mix) and they are still there, good as gold too.

In those early days there was a difference ($$) in having the stone delivered in bulk vs a mix in a bag. Not so today. It is a lot of work mixing, if you do get a truck be sure you have enough help. A guy down the street poured his own driveway (from a truck) and couldn't keep ahead.........some of it is pretty rough. Only saw it after the fact or would have given him a hand.

Good luck, and let us know how it turns out.

Why not lay down some sand and use patio pavers for the floor? I think you can get them as large as 24" x 24".

I did that in my 5' x 15' woodshed, using 16" squares then handmixing concrete to fill in around the edges.

They should be more than capable of withstanding anything you'd put into that area.

Der Bugmeister said:

Why not lay down some sand and use patio pavers for the floor?...

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I'm currently installing 8x16x3.5" solid concrete 'pavers' in the carport and pad area of my 3 bay garage. Compared to mixing the 75 - 80lbs bags of concrete to fill the cores in the stem wall, setting 550ish of these 30lb pavers is a piece of cake

Funf Dreisig

boiler7904 said:

Without knowing your location, I'm thinking that need more than a simple 4" thick slab in order to tie into the existing garage foundation and still meet code. At a minimum I would think you're going to need a 12" deep turned down edge on the slab. That's going to add about another 1/2 yard. If you are in a cold location requiring footings and frost walls, you're looking at a few yards. For less than 2 yards, I would rent a small tow behind mixer. You have too much to do by hand from bagged mix and still be able to get consistent results without creating cold joints in the concrete.

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It's a lawnmower shed, not a SPACE SHUTTLE launch pad!!!!

Exciting project, good luck with it! I live in the SW Chicago burbs and built a 10x12 shed from scratch a few years ago. The inspector in our county (Will) said more than 100sqft requires concrete slab, less can be wood or concrete. It's a floating slab, 4-6" thick with about 2" of gravel below it tamped down. I pounded in about (8) 1/2" x 4' rebar vertically in the ground ~3.75' thinking that would help, tied to the horizontal rebar. It probably didn't but made me feel good I had 2.5 yards delivered for ~$320 from Ozinga (the first yard is the most expensive as that includes the truck cost too). The driver was patient with us as my brother was driving a borrowed bobcat. I overbought 1/2 yard as I didn't want to run short, so I framed up a garbage can pad which I was able to fill also.

For 5' x 15', delivered or bags - it all depends on the price. I just bought a few for a mailbox post and they were ~$3.50. So $160ish + mixer rental should be compared to 1 cubic yard delivered, and any wheel barrow rentals you'd need. I don't see hardly any concrete trucks on the road in our area compared to the last 5 years, so I'd imagine they are looking for business and would deliver a smaller load.

If you do go with the bags, shop around and pricematch. I would find the cheapest 80lb quikcrete bags and pricematch it to your favorite bigbox store. Last year I built a fence and needed (80) 80lb bags of concrete for the fence post holes. Menards had it on sale, so I pricematched it to Lowes and got an extra 10% off. Lowes delivered it on pallets wherever I wanted it. I mixed these by hand over 3 days in a wheel barrow. But for a shed slab, you could have them drop the skid next to the slab and rent the mixer and have it hopefully done in several hours with some friends.

If you do use concrete instead of blocks or wood, don't forget to get the moisture barrier padding to go between the concrete and the bottom of your wall, and use treated lumber for the bottom of your walls. Also, decide if you're going to put J anchors in the concrete when it's wet, or put in something like redhead anchors after the fact. I put J's in mine, and used redheads in several of my friends' sheds lateron, and I like the redheads afterwards. Much easier to line up between the studs and center after the fact when you are putting up the walls and squaring it all up.

Good luck with it!