Shed build & flooring advice (cement)

[busastars]

Im in the next few weeks going to build an extention to my original shed. The original shed is 6 1/2' x 12 1/2' concerete floor timber frame etc.

The extension will be aprox 8' x 16'

Stud work will be 2"x2" and panneling will be 3/4" external ply.

Because of doing all the work in 2"x2" I had a thought of doing the floor in concereate 2" thick.

Does 2" sound thick enough?
If not what thickness do I need?

What mix of sand, cement, stone do I need?

Chears

 

[rtbcomp]

I'd go for 4 inches and Redimix.

 

[Justme]

What will you do in it?


If jacking up cars or using stands, hoists or even heavy kit then 2" is far to thin. Think 4" to 6" & pos reinforce it. Also remember to dig out to 2 or 3 times that to a good solid base (so all the soil out to the sub soil level) & then back fill with crushed hardcore & tamp it down well. You might also need to do it in two sections & have a flexi joint in between to stop it cracking / snapping.

 

[busastars]

Chears,

My first plan was to do the floor in 3/4" ply but thought concereate would be better. Its a shed, most heavy thing could be the bike around 200kg, the lathe BUT may keep this down the bottom in the original part, im gessing around 3-400kg. would do in about three sections.

Never for a car, just my workshop/shed for the bikes.

Im mainly struggling with time etc.

How would 2" thick cement and layer 3/4" ply ontop. Need lots of suggestions please.

 

[Shox Dr]

The Concrete mix need to be 3-2-1 thats 3 sand, 2 gravel, 1 cement

It needs to be at least 4" thick on a compacted base of stone 6" thick. otherwise it will crack, through heat/weight/movement etc etc

 

[cazl1994]

the ply on top won't make much of a differance
put 4-6 inch of concrete down about 4-5 to 1 strenght and 1-2 expansion joints in it
then it should be fine and dig enought out and wack it down hard

 

[busastars]

Gess ill need to get digging

Ok, to cover 16 x 8 foot @ 4" thick how much material will I need, ie: how many bags etc.

Just so I can do a costing while pulumped on my fat bum

 

[Richm]

A 3-2-1 mix is 3 stone, 2 sand, 1 cement.4-2-1 would be fine. What is the ground you are planning on laying on like?
Rich

 

[busastars]

Not 100% sure what the ground is like, there is all stones over a layer of sheeting where I intend to extend the shed.

Im gessing its just mud/clay.

Looks like its turning out to be a larger project than I thought. Planed on a few days tops, already got 15 sheets of 8x4 3/4" ply, 16 lenths of 2x2" 2800mm long.

 

[pedrobedro]

If you are going to mix your own you want ballast, which is gravel and coarse sand already mixed. 6 to 1 ballast to cement should do you but make sure you keep the measurements something like and don't just throw a shovel of cement in when you feel like it or it will crumble. There are calculators available for the area but everything is metric these days as in cubic metres for concrete. Calculator site.

 

[Charred fingers]

You should be able to get away with a 21N mix for a shed floor or 4:2:1 in old money. For the sizes given thats approx 1.2 cubic metres at 100mm thick which comes out at around 680kg 19mm gravel, 340kg sharp sand and 170kg cement. In reality both the sand and the gravel come in 1 tonne bags so its 1each of those, as for the cement because you are working by volume not weight 7 25kg bags would a minimum but be prepared to use more. You should use a batch box or maybe a small bucket to get the volumes equal. One fibre board expansion joist at the mid point would be enough everything laid on a DPM.AS everyone else says base preparation is most important.

 

[busastars]

Its looking to expensive, realy need to think of other options. Its not my house im renting it but I do have permision to do what I want.

I need workshop / bike storage space and need it FAST but carnt splash out loads of cash. Only very recently got back in work so got to hold back on trying to splash out.

Already have the timber as the Ply came my way cheap. Originaly was going to do it all in timber with 3/4" Ply floor. My thought before I started collectin things was its only a shed and most sheds you buy are flimsy as hell with only being layed on gravel.

Feal a little lost now

 

[rtbcomp]

If your circumstances won't allow you to do a proper job then you'll have to make do with what you can afford. If you put a ply floor down, lay a polythene sheet on the ground, then some joists then the floor. The joists will allow air to circulate under the floor

 

[pidgeon chit welder]

slight cheaper than full concrete , stronger than ply .....look at the other threads using the site search facility for " shed floor "

19 mm all in one or mixed ballast in 1 tomme bags delivered with your cement may be useful. Mix it, rake it fairly level before compacting with any compascter or even your size 9's if desperate ..re rake the top gently .
for poly sheet. Use planks to sack barrow the slabs into the basic position .


.. 2 nd hand paving slabs on 4 inches of compacted & levelled dry mix of 1 part cement to 8 mixded ballast by volume , make a open bottom box 1 cubic foot square with rope pull offs and use that for the guaging if you want a reall good lean mix ( cheaper than 1 to 6 ) and the moisture in the earth will send it off to set over a few weks ..after 28 days the strength startds to increase to a max of approx 80 years.


Lay a poly sheet on the dry mix so you can take the slabs with you when you go.

Lay your slabs like a running brick bond to off set the joints and give greater strength, cut halves or what ever size you need and reuse the odd bits to make up any pathway to a door.

 

[busastars]

Thats the thing, its mainly for the bikes. bikes out there are around 150- 230kg. Few wooden benches etc.

So desprate for room, leaving the bikes outside is killing them, carnt have trickle charger on them, carnt stop them rusting before my eyes, carnt stop the calipers sticking.

Got no space to work on them in the dry or do any work in the dry.

Simple answer is dont have the bikes, do potter about etc but then whats the point, what a boring life. Used to have my own Garage/workshop setup, realy miss having all the space and time away to myslef pottering.

So my thought originaly was to build a heavy duty timber shed, thats why I started to buy cheap stuff that turned up.

 

[SC_BK]

You can usually get used 3x2 slabs for about £2 but they sell fast and in the end I had to buy new ones at £5.
I think you'd need about a tonne of sharp sand for 16x8?
As per the other thread, used scaffold boards make a good strong (and cheap) floor

 

[tigler]

Shed building is also in my immediate future !! Am interested to read you are using 3/4" external ply , this is something that occurred to me. Will that be shuttering ply , I think that's the stuff used for boarding up smashed shop windows ?
How will you be protecting that from the elements ?
The shed I need to build is for housing my Lister CS Diesel Start-O-Matic generator which will be used as a CHP plant and to store some motorcycles so I can use my currently stuffed full garage as a workshop !!!

 

[pedrobedro]

If you use slabs I laid mine on 3/4" to dust limestone chippings mixed 9 to 1 with cement and screeded out between two 3x2s. They've been down 30 years and never budged with cars and foot traffic.

 

[Robotstar5]

What about putting concrete pads in, couple of bricks on top and your floor support joists across them?
The span between pads would be dictated by the joist size.

 

[Pete.]

Kelvin the floor you want to lay would cost less than £100 in readymix. If the truck can get within chute-range of the base all you gotta do is have them shoot it in then level it off, wait until it starts to set then trowel it in.
2" is too thin but for what you are doing 4" would be fine even with no rebar. My base is 4" of readymix straight onto a 1000GSM sheet laid on the dirt. It's been there a couple of years now with no sign of movement or cracking and has had 5 bikes, my lathe, mill and lots of other stuff on it at one time. I got 1.5 metres of readymix for £90