concreting shed floor

[chris718]

Hi,

I've just finished putting up a 6x9m shed... now I need to concrete the floor
I was just wondering if anyone has had experience doing this before, and could give me a few pointers....
normally when you lay a slab you have the boards along the sides, which you run the screed board along the top of, to get a level finish... how do you do this when you're concreting the whole inside of the shed? (if you put the boards in along the edges, they will get concreted in).

Also, normally you can stand on either side of the slab to level it with the screed board, obviously you can't to this with the shed (because the walls are there)

hope you understand what I'm talking about.....
any ideas?

Thanks

[Barry_White]

Use the foam jointing material. Not sure what it is called now but the old bitumous material used to be called Jointex.

You don't want the concrete to go up against the wall sheeting as it may cause corrosion.

If you are using ready mix concrete hire a vibrator to get the concrete to find it's own level and then lightly screed with an aluminiun screed or finish with one of thos screeds that have a curved plate that can be rocked from one side to the other. You should be able to hire all that equipment.

Extra comments:

You could also level spots all over the concrete and screed to these, The only thing is you need a dumpy level or laser level to do this. Also can be hired.

[johnc]

You will I assume have a board at the front of the shed which is your reference point. A dumpy level is handy, but if there is no plastic you can drive a series of pegs into the ground to get your heights then screed off to those. You use the pegs to get a straight, level line of concrete and then use two of those as your screeding straight edge (form work). You need to screed through without reducing your levels and the pegs need to be pulled out before finishing. You can make up boning rods to help check heights between known level spots, and you will need cheese boards, and the wobbly thingy is a bull float. I would suggest as you are asking these questions that your skill level will be heavily challenged on this type of job.

FWIW I would prepare it, get it ready and hire a concretor to help pour and finish, I would suggest it's worth every penny against the chance of stuffing it up. If you don't care if there is the odd mound or hollow then go for it.

John.

[KevM]

If you've gotta ask how then don't do it.

Prepare your base, put down your damp prof course, lay out the mesh and tie, mark out your levels on the side then pay an expert to do it properly. It will only cost you one day for two men. You will live to regret doing it yourself if you are not experienced.

[Bleedin Thumb]

Mate what is the shed sitting on now? Dirt?
My best advise is undo and remove the shed, set up and pour your slab with a minimum of 50mm overhang all around and reassemble the shed.

I hate to tell you this but you are going ass about face with you construction technique.

The shed has to sit on the slab.

EDIT tell us the name of the shed supply company and if they assembled it for you so we can all avoid them.

[KevM]

Mate what is the shed sitting on now? Dirt?
My best advise is undo and remove the shed, set up and pour your slab with a minimum of 50mm overhang all around and reassemble the shed.

I hate to tell you this but you are going ass about face with you construction technique.

The shed has to sit on the slab.

EDIT tell us the name of the shed supply company and if they assembled it for you so we can all avoid them.

Not true bleeding, I've done two sheds this way, one 9mx6m , 12 years ago, finished by pros, using laser level, the second one 12m x 9m but this one had to be done in two stages as I needed secure storage on site and the shed was all I had. Not a problem with either of them.

[Bleedin Thumb]

Why wouldn't you pour the slab first?

[KevM]

I built the 9 x 12 shed on a 100 acre block I had 17 years ago, believed at the time that I would never need it concreted. It was to be used for general machinery storage & hay, so I put down 30 tonne of FCR and levelled it before the shed went up.

Found a need some three years ago to have a better environment for dry timber storage so then had pro's concrete the floor after I prepared the base. The smaller shed was done that way 13 years ago on the recommendation of the shed builder.

BUT next time I would put the slab down first as it is easier to finish, but I did get my finishers in earlier on my sheds as they could do them when other jobs were cancelled due to possibility of bad weather, not a problem with rain when you have an existing roof over the wet concrete.

[Barry_White]

Why wouldn't you pour the slab first?

I agree that is the better way but when I was selling and building sheds probably 25% of sheds we sold had the slab done after and a lot never had a slab especially with rural sheds.

If you build the slab with the piers the council will want the slab engineered and engineers don't miss you. If you build the shed just on the piers the shed supplier will give you the engineering on the piers as part of the shed and then you can do the slab without the engineering.

Added Comment: If the piers are boxed up and leveled this will give a datum to work to for the slab.

[Bleedin Thumb]

Yes I guess in a rural situation.. where you dont need a slab. But unless youre broke and you cant afford the slab first you are sure making life hard for yourself.

[Barry_White]

Yes I guess in a rural situation.. where you dont need a slab. But unless youre broke and you cant afford the slab first you are sure making life hard for yourself.

Probably if you aren't a concretor, but to a good concretor it wouldn't make any difference.

[Bleedin Thumb]

I would much sooner screed off a slab with the form board expossed than to work inside a shed screeding across reference pegs any day.

[Barry_White]

I would much sooner screed off a slab with the form board expossed than to work inside a shed screeding across reference pegs any day.

That maybe so but the concretors that did my brother-in-laws slab which was 6 x 9 didn't even use the the form boards to screed off the slab. The longest screed they had was 2 metres. They just created spots all over the slab about 1800 apart with a float by dumpying them using the form work as a reference for height and just screeded between the spots with the 2 metre aluminium screed.

The beauty of this method is that they aren't trying to move large amounts of concrete with the screed.

The other important thing was that they vibrated the concrete which helped to reduce the amount of concrete above the form boards thus reducing the screeding.

[Bleedin Thumb]

I take it that your brother in laws was not inside a shed.
If it was they would have trouble with accessing all around the slab with a 2m long screed.
I also assume they had a bull float with a nice long handle for finishing off - which, whilst not impossible, would be a PITA operating from the doorway of a shed
The other thing is (from memory) every time I've ordered a shed (4 or 5 now) the supplier has requested that I have the slab prepared beforehand so I would assume that it would cost more for them to assemble if you didn't have a slab in place. Is that right?

[Barry_White]

I take it that your brother in laws was not inside a shed.
If it was they would have trouble with accessing all around the slab with a 2m long screed.
I also assume they had a bull float with a nice long handle for finishing off - which, whilst not impossible, would be a PITA operating from the doorway of a shed
The other thing is (from memory) every time I've ordered a shed (4 or 5 now) the supplier has requested that I have the slab prepared beforehand so I would assume that it would cost more for them to assemble if you didn't have a slab in place. Is that right?

Makes no difference in erecting the shed because the footings have to be in place to erect the shed on. The company I worked for used to supply the footing bolts to be cast into the piers prior to the shed being erected.

The major problem comes from the sheds being built on a big slope without a slab. BTW we used to build some big sheds up to 21 metre spans up to 50 + metres long and 6 metres high and these were all build out of "C" section