Concrete for shed foundations

DamoNolan

I'm building a shed and just wondering on costs of getting the concrete foundations premix and delivered or mixing it myself its a 4mx3m 400mm deep..I know it would take alot more time mixing it myself but just depends on costs..has anyone got any ideas of cost of concrete these days?

Calahonda52

so the slab is 4*3 by .4: 4.8 m3, or 12 tonnes

DamoNolan

the slab is going to be 4 meters by 3 meters and 400mm deep

Bonzo Delaney

4.8m³ slab mixing yourself is about 100 mixes at 7 minutes a mix is about 12 hours non stop mixing 8 ton of gravel and 35 bags of cement plus a 1000 liters of water literally a ton of water. Material costs would be about the same about 450 -500e time wise hire a small dumper an you'll have it done in 2 hrs

mickdw

Sounds like complete overkill to be going 400mm deep on a shed 4m x 3m.
Perhaps 400 deep around outer edge but not all through.

martinr5232

400mm is sixteen inches are you sure thats correct ??
What are you planning using the shed for ? If its just storage or garden shed 100 to 150mm would be plenty.
Either way id still go the readymix route if you can at all.

DamoNolan

Thats exactly wat I was thinking just around the edge and smaller depth for rest..im thinking of just ordering concrete save myself the hassle of mixing..whats the going rate for a m3 of concrete. Just standard stuff nothing special

martinr5232

DamoNolan wrote:

Thats exactly wat I was thinking just around the edge and smaller depth for rest..im thinking of just ordering concrete save myself the hassle of mixing..whats the going rate for a m3 of concrete. Just standard stuff nothing special

About eighty euro.

DamoNolan

martinr5232 wrote: »

About eighty euro.

Ye that seems grand actually..saves the hassle of self mixing..how much do you reckon I would need..

DamoNolan

I forgot to mention this is for a block shed so is there a minimum depth I need to go

martinr5232

DamoNolan wrote:

I forgot to mention this is for a block shed so is there a minimum depth I need to go

Anywhere between 100mm and 150mm depending on the ground you're building on.

Stihl waters

400 deep is nuts

vicwatson

Can i hop in here and ask if the likes of that would need a hardcore base and reinforcing mesh?

mickdw

vicwatson wrote: »

Can i hop in here and ask if the likes of that would need a hardcore base and reinforcing mesh?

What i generally do for a shed - 150 timber with 75 or 100 high timber stepped in on top to create a step.
Allow the full depth for 600 wide around outside and reduce to 150 for the rest.
4 12mm bars in base around outside and if you want a sheet of mesh near the top.

vicwatson

What N needed for this (where no cars etc on it, just a few people) someone said 30 N to me but from what I can see it wouldn’t need that strength ???

mickdw

Get 30

garv123

is it going to be 4x3 x20 storys high? if so 400 should be ok.

vicwatson

mickdw wrote: »

Get 30

Really? With 10mil reinforcing bar and a depth of 100 mil concrete? Seems a lot overengineered no?

Lumen

Thoughts and prayers for whoever has to demolish this thing. :pac:

Stihl waters

Jesus christ the specs in here would bankrupt BAM

mickdw

Stihl waters wrote: »

Jesus christ the specs in here would bankrupt BAM

Vic watson isnt the op. I responded to his query without knowing what size the shed is.
My suggested design would be minimum required for any kind of decent blockwork shed.

Steeltech themselves recommend a 30N strip foundation 100-150 depth and 300 wide on top of 804. When the shed is installed, 25mm of blinding sand should be installed with a 2000 gauge DPM on top of it before pouring the 50mm finished floor.

The Mighty Quinn

mickdw wrote: »

Sounds like complete overkill to be going 400mm deep on a shed 4m x 3m.
Perhaps 400 deep around outer edge but not all through.

Agreed....
Recently finished a project where there was 11 metre high pallet racking in a warehouse and the slab was 225mm thick with A393.

Working on a water project at the moment where a tank holding 500 cubic metres of water has a 400mm thick concrete base.

I'd rethink your depth of concrete.

400mm sounds huuuge

vicwatson

Is €150 per cbm for 30n10 ott or in the ballpark?

Seems very expensive

sgarvan

Recently laid a 4.5m x 3m x 4cm slab for a relative. Used 2cbm of readymix and it was €250 delivered. That included the truck staying there for 45mins and any more time was €15 per 15mins.

DamoNolan

sgarvan wrote: »

Recently laid a 4.5m x 3m x 4cm slab for a relative. Used 2cbm of readymix and it was €250 delivered. That included the truck staying there for 45mins and any more time was €15 per 15mins.

Can I ask who you got the ready-mixed off?

vicwatson

sgarvan wrote: »

Recently laid a 4.5m x 3m x 4cm slab for a relative. Used 2cbm of readymix and it was €250 delivered. That included the truck staying there for 45mins and any more time was €15 per 15mins.

Was it 30n10 ?


Included VAT?

Fine Cheers

Got my own slab for shed poured this week 2m x 3m 75mm thick increasing to 120mm (sloping ground). Put in dpm alright, no steel. Readymix the only way to go, lads barrowed it in and was all done in half an hour. Dont have finalised price yet as was piggybacking a neighbour who was doing a bigger pour. Had contemplated hiring a mixer and going DIY as I was waiting months but happy I held out.
Its the delivery / waiting charge you need to look out for, especially for smaller loads.

Lantus

If it were me id go with 100mm of sub base of compacted 804. A plastic sheet, Then 80mm to 100mm of concrete with a light mesh say 6mm. It adds a huge amount of strength to concrete. its probably a bit overkill but a good job you can walk away from.

About 1.2m3 of the good stuff. Assume a truck can get in or you have 3 barrows and strong men on hand to ferry it.

Timber frame it so you can run a timber over it to level it off.

https://youtu.be/H56eiJJ_FCY

Try here for a good video.

vicwatson

Is a plastic sheet necessary for a slab that’ll be outdoors?

vicwatson

vicwatson wrote: »

Is a plastic sheet necessary for a slab that’ll be outdoors?

Unless you want the interior walls of your shed to be soaking wet from rising damp, then yes.

Lantus

vicwatson wrote: »

Is a plastic sheet necessary for a slab that’ll be outdoors?

Generally good practice for damp and protection of the concrete. I laid plastic down for my driveway. A little ott but I sleep soundly...

Lumen

The least amount of effort for a shed has to be a deeper meshed slab and minimal ground prep, i.e. remove topsoil, shutter, mesh and pour.

Digging out subsoil is a right pain in the hole.

148multi

vicwatson wrote: »

What N needed for this (where no cars etc on it, just a few people) someone said 30 N to me but from what I can see it wouldn’t need that strength ???

30n would be a minimum strength, adding water to this mix to make it more workable will significantly weaken the mix leaving you with a lower N mix. the type of ground will dictate the dept of foundation, but most will be in the region of 9"-10",a lot of Quarries will have a minimum charge equating to 4 m3, plus a charge for every extra hour the truck is there. In certain circumstances it may be much cheaper to get a crew working local to do the job as they can get an extra m3 or two for a fraction of the cost available to Joe soap. Another option is to collect a dry mix from the quarry yourself, but the shut filling will be high, so two sheets of ply or similar to funnel the mix is essential.

tmabr

Can you buy a ton bag of concrete anywhere. Ready mixed. ?
Ty

vicwatson

Lumen wrote: »

The least amount of effort for a shed has to be a deeper meshed slab and minimal ground prep, i.e. remove topsoil, shutter, mesh and pour.

Digging out subsoil is a right pain in the hole.

And the arms and back :-)

Lantus

Lumen wrote: »

The least amount of effort for a shed has to be a deeper meshed slab and minimal ground prep, i.e. remove topsoil, shutter, mesh and pour.

Digging out subsoil is a right pain in the hole.

Yep. Effort vs cost and of course the ground conditions. If it's well compacted ground then lashing down 150mm with a 10mm mesh would be pretty bomb proof for a small area like this.

148multi

tmabr wrote: »

Can you buy a ton bag of concrete anywhere. Ready mixed. ?
Ty

You can bring a tonne bag to the quarry, but can't leave it, it goes off even when dry.

sgarvan

DamoNolan wrote: »

Can I ask who you got the ready-mixed off?

Kilsaran

vicwatson wrote: »

Was it 30n10 ?


Included VAT?

I didnt order it so not 100% sure on the concrete type, I will find ask. I would say it did include VAT.