How much is a simple concrete slab for a barn likely to cost?

[reddal]

Hi,

 

A friend of mine is looking to put up a barn in their farm - it will be a simple steel frame building - about 28m x 14m, and they will probably buy a kit for the building itself.

 

However they will need to lay down a concrete slab for the barn to sit on - and asked me how much the groundworks plus slab would likely cost ballpark.

 

It doesn't need to be anything fancy - just a solid floor the steel building can be attached to.

 

What do you reckon they should budget for that?

 

thanks - reddal

[Nickfromwales]

Prob best to mention the location

[Crofter]

You will need:

- excavation down to firm subsoil. Very site dependent, but presumably your friend will have somewhere to put the spoil. Probably a day's work for a decent sized machine and dumper, plus on-site costs. At the rates I paid, that would be about £400.

- import sub-base material and whacker it down. If you want a 100mm base, you're looking at about 40m3, or about 80t, which is going to cost about £2000 at the price I pay. Hopefully you're closer to a quarry and can get it for a lot less.

- pour a 100mm slab of concrete, 40m3, that would cost me around £4,500

So far, that's around £7k.

 

You'd almost certainly need rebar in there, not something I have had to price up personally.

Plus labour for a pour of that size, unless you have lots of friends who owe you favours.

 

The above spec is a bare minimum. You'd be fortunate if you found that you had good solid ground 200mm down, and a 100mm slab is probably insufficient to support anything other than very light loads. It would at least need localised thicker sections to support the steel frame.

 

Will be interesting to see just how high my local prices are compared to other forumites...

[PeterW]

What is going in the barn ..??

 

We do barns with pads - 1/2 cube each and dug with an 18" bucket. 

 

One pad per leg, and then a shallow 8-12" trench between the legs for the panels to sit on once the frame is up. 

 

If you want a straight ag slab with  capacity to take tractors etc then you need 150mm of reinforced concrete over a good 150/200 of MOT1. Anything less can go on 100/150 laid in bays with mesh per bay. Don't span the bays with rebar as it's easier to take one bay up when it needs it. 

 

 

 

 

[reddal]

30 minutes ago, Nickfromwales said:

Prob best to mention the location

 

Its in the Isle of Man - but I was going to add at least 25% to any numbers people gave to account for that :).

 

15 minutes ago, PeterW said:

What is going in the barn ..??

 

One half will be for general storage including vehicles - so will need to be able to take some weight. The other half wont need to be as industrial (animal stalls, etc) so wont need as much.

[PeterW]

So it needs floor plates inside. 

 

Use the build up as per the previous post - concrete piles for the legs and fill it in from there 

[Temp]

If you they are going to be driving heavy vehicles in and out then I think the concrete should be around 150mm...

 

http://www.pavingexpert.com/concrete.htm

 

Concrete paths should be 75-100mm thick, whereas drives, garage bases or hardstandings should be at least 100mm thick. For heavier use, such as large vans, use a 150-200mm thick concrete slab. Concrete slabs intended for exceptional loads, such as commercial yards, lorry parks etc., will be at least 200mm thick and should be specifically designed as they will probably require a

sub-base of at least 100mm thickness, and steel reinforcing mesh or a fibre-reinforced concrete.

 

Should also think about drainage.  Will the barn be standing on stub walls or direct on the concrete slab? Common mistake with a shed base is to make it bigger than the shed so you end up with a flat strip of concrete around the outside on which rainwater can land and run under the walls. If the slab is fractionally smaller than the shed and raised above ground level then rain drips off the walls onto the surrounding ground/gravel anti splash.  Best check what detail the building supplier recommends. Likewise at any door way - do they need a linear drain or concrete channel to stop rainwater running in under the door?

[reddal]

Hi,

 

This barn is now up and the slab is about to go down. What do I need to buy to reinforce the section that takes vehicle traffic?

 

That bit is 9m x 14m and we are planning 150mm of slab for it - but how much reinforcement is needed?

 

Should I plan to put a single layer of this stuff down? - https://www.metals4u.co.uk/mild-steel-reinforcing-mesh/a252-8mm/p10832

 

Maybe lifted off the ground with these? - https://www.metals4u.co.uk/mild-steel/c6/concrete-reinforcement/c2042/supports-and-spacers/c2045/plastic-floor-spacers/c2064/90mm-100mm/p12359

 

Or do I need 2 layers of mesh or something different? As you can tell I don't really know what I'm doing - but somehow I'm doing it anyway so any advice greatly appreciated :).

 

thanks - reddal