questions about concrete

[SgtBilco]

I am planning to pour concrete between two structures. the back and one side is basement wall (cement blocks) on other side is concrete slab with aluminum storage shed. the space is 11' x 3.5' and I am in Michigan.

Do I need expansion joints? if so is there a way to attach/glue them in place? the alum shed has a flange thing on wall that goes over top 1" of slab, and is not tight against slab in some places.......so sticks out a bit....like 1/8" or so. what is best way to deal with this?

I have some paver/driveway base material that is crushed limestone I believe....will 3" of this material work for foundation with no sand?

I am planning to pick up 60 lb bags of "Quickrete" concrete and mix in wheel barrow. how and when to seal?

[Jeff The Drunk]

[HeyBub]

That's 52 cubic feet of concrete (11 x 3.4 x 4"). That's 30 sixty-pound bags or 23 eighty-pound bags. (45 & 34 respectively for a 6" depth) - almost a ton of dry concrete.

Not a completely awsome task, but I'd buy a HF cement mixer for $150 or less and plan on selling it on Craigslist for $100 after. Or, I suppose, you could rent one

[Colbyt]

Using the expansion joint stuff or scrap 1x material along the house and shed does two things. It keeps the concrete from bonding and it gives you a screed point to level your pour.

Sidewalks do not need footers. Crushed stone is used to level and fill and also to provide drainage. Coarser crushed stone would be better but the leftover stuff will work.

You should score or cut later a control joint across the 3.5' dimension. Two should be enough. One every 4-5 foot on sidewalks is the norm.

80 pound bags are more of a PITA but the final cost is a lot less than using the 60 pound ones. You pay dearly for the lighter weight. 11' x 3.5' x 4" thick = 12.705 cubic feet of mix. An 80 pound bag yields .60 cubic feet. True math is .66. Experience is .60 12.705 .60 ÷

--------------------------

21.175 = 80# bags of concrete

Since I know an 80 pound bag yields .60 cubic feet I must assume a 60 pound bag yields .45 cubic feet (75% of .60) That would take about 29 bags.

Note that I always buy 10% more rounded up to the next full bag than the math call for. I rarely have any to return.

[Colbyt]

HeyBub

Where did you learn math? Using your number, not the real ones.

11 3.4 × .33 ×

--------------------------

12.342 = cubic feet of mix.

Cheers

Colbyt

[SgtBilco]

how do i hold expansion material in place? glue in place?

[cavedweller]

Is that you "stryped"?

[Colbyt]

Anything that works for you. Once the concrete fills the forms nothing else will be needed.

[Ralph Mowery]

As others calculated you are in for a bunch of bags. I mixed up 43 of the

80 lb bags to fill a hole about 3 feet each way. I did rent a mixer for about $ 40 to do the job. It was a small mixer but that was what I wanted. You can spend a lot of time doing the mix. Think about 5 minuits per bag.

Small jobs are a pain to do. You spend a lot of time and can almost get it delivered for what it cost to mix up a yard of cement. Most places want a big delivery charge or they want to deliver several yards. I could have had the stuff delivered already mixed for almost what I payed for it. Also you need to transport all those bags home. It may require several trips with a truck. I hope you have a strong back.

[HeyBub]

A government school.

[aemeijers]

Lordy that is a lot of work to neaten up a dead space. I'd just put down landscape fabric to stop the weeds, and lotsa gravel to cover. If you put a slab there, where is the rain water gonna go? I presume into the shed is not a desired path. Shed slab and house foundation will move relative to each other as seasons change, so you will either get cracks in your new slab, or gaps at the edges.

That shed is way too close to the house, by the way. Did you do it, or did previous owner? And does you insurance company know? They may not want you keeping gas cans and such in there, since if it lights off, it will likely spread to the house as well.

[SgtBilco]

this project is open on one end only back side buts against basement left side against crawl space right side is "shed" well not really a shed...I just used that word because I don't know what else to call it...it is 3 sided alum structure 11' x 12' attached to back of garage....has 4 large windows on each wall...walls are about 7' tall. it sits on slab that slopes away from garage (previous owner put it in I guess, for what purpose I do not know) .... the new concrete will follow slope of "shed" slab so water will run out the open end....

I want to put in concrete to clean up and make more functional ....right now this area is getting way to wet and causing problems in basement. was so wet it has taken 4 weeks to dry. I have kept covered with plastic when it rains and not covered rest of time.....this area gets almost no sun and lack of air circulation has taken very long to dry out.... the way roof's come together result in too much water.....also wind blown rain is the cause. so I need to do something...

I have just completed the prep work...and is all formed and ready to go...I decided to extend it out a few more feed past "shed" so about 50 square feet.........according to Quickrete calculator

for 4" slab I need either

38 60 lb bags or 29 80 lb bags..... I just came from home depot and 60 lb bags are 2.65 per bag and 80 lb bags 3.74 per bag............so is actually cheaper to buy smaller bags...which is what I did.

I also picked up expansion joints....I have helper to mix concrete in wheelbarrow tomorrow, so I don't think it will be that big of a job.

[Uno]

Still. That's a huge pad for quickrete.

Michigan had a variety of basement frequently where the outside walls of the house rested well outside of anywhere you could stand, and the walls were slanted out as they went up. It made a lot of sense in terms of spending the least amount you could on a foundation and still have some type of basement to go to.

[Uno]

Is there ever concern about the wood swelling or rotting?

[dadiOH]

It will swell, the concrete doesn't care. It will also rot; when it does, you still have an expansion joint...if you don't like the void, fill it with sand/gravel/tar/goop of your choice.

[EXT]

The best, easiest and in most cases the cheapest route to follow is to check your local yellow pages and look for a company that has a "mobile mix" or some other name to designate a "mix it on the spot" truck. The truck is loaded with Portland cement, sand, gravel and water. It is mixed together continuously and comes out a chute into your form or wheelbarrow. When you have taken enough you say "stop" and they turn the machine off, no waste and no shortages, just the amount that you wanted. There is a meter on the side of the truck and it prints the start and finish quantity that you took and the driver prepares the bill for the amount you used and then drives off to the next delivery. Many cities have at least one company doing this, in my area there are 3 spread across the greater city area.