Barn floor in concrete

[Ian X]

Plenty of forums elsewhere that this question could have been posted in but the floor needs to bear the load of machinery and not vibrate unduly so this is the first place to ask.
I have a barn that needs a floor. It is 12Mx5M rectangle. Currently it is 200 year old dirt floor. Heaviest machine is shy of 1,800Kg. No long bed lathes involved, the four soon to be five machines are compact and most sources say no special requirements on depth of base.
Kearns S type manual suggests 12" concrete but reliable sources say that machine is happy on a lot less.
For anyone who has had to lay a floor or called in contractors to lay a 60M2 or larger floor I am eager to know what you specified and even what you spent.
My current notion is to dig out to +30cm, lay mixed ballast to 15cm, sand then Kingspan or other batts to 3.5cm on top of membrane and pumped concrete on rebar to 12cm.
Power float finish and epoxy surface coat.
It has to be pumped concrete as the site is on a tight bend on a narrow road with no turn in for a mixer and the time on site needs to be minimal.
It is over 7m3 at 12cm depth and as yet I have not a clue what mixer capacity is in France. Work I have done in the UK it is usually 6M3.

 

[addjunkie]

Digging down in an old dirt floor becareful you dont get below the bottom of the walling stone, think id be having a test dig just to see how deep the stones are.

When refurbishing my house, i made a decision to dig out old floors for underfloor heating, they wee all cracked anyway. In a few places we ened up deeper than the bottom of the walls.

 

[Wendelspanswick]

If your floor is well compacted why dig it out and then add loose ballast back in?
I would dig it out to (sand + insulation + Concrete) thickness.

 

[Pete.]

I am of the same mind as Wendelspanwick. A barn that size should have the dirt floor compacted by plant or animals I see no reason to excavate a foot of dirt to add loose ballast unless you have a 2 ton vibrating roller to hammer it down and that might not be good for a stone building either. I'd leave out the ballast and stick in extra concrete over the dirt. Shifting that 10 ton of dirt won't be cheap anyway.

 

[mike os]

I would have gone for 150mm to200mm concrete, not worth doing it twice

1 layer of mesh 40 to 50mm up from the bottom, another the same down for a posh job, will take anything you can throw on it

 

[BrokenBiker]

I was going to suggest the same as Mike...8" of concrete with mesh at 1/3 deep and 2/3 deep and you should be fine

 

[JohnRUFC]

I would guess you have roof space to spare, have you thought about leaving the floor and working on top of the hard base you have? Putting a small sloped ramp to the door? I'm not sure what you are doing inside it but I would love a small ramp on my garage to roll cars out haha.

 

[colnerov]

but I would love a small ramp on my garage to roll cars out haha.

You mean like 'drive em in, push em out'?

 

[ronan]

Do you need plannng permission to put a floor in a barn ? I thought barns were allowed to be built without pp if they had a dirt floor as they were not classed as permanent structures.

 

[addjunkie]

Not sure about france, but up the country, id not even consider aplying for planning to put a concrete floor in my buildings, nor a new roof, you are allowed to maintain your buildings.

Planning for agricultural new builds isnt that difficult either. Garages are but barns convert to garages easily!

 

[JohnRUFC]

Yeah haha, only one thing that goes in to my garage comes back out in on piece!

 

[DecK]

Depending on ground condition, ( 2" square timber stake pointed and a 4 lb lump hammer you should meet resistance to hammer the stake 6" into the ground if soil is suitable. This isn't a standardised testing method but it will give an idea as to what you have. Used it enough times signing off foundations ), either dig it out if you have to or else pour on top of existing or excavate to a level that suits for finished floor level.
6" of 25N concrete would be well enough to carry that load with a layer of mesh on its own. You could layer T16 reinforcement bars @400 c/c on the mesh for extra reinforcement and probably cheaper than 2 layers of mesh and support chairs but I don't think it's needed.
I'd give the underfloor insulation a miss too and put the money towards concrete. It's not going to help with the cold in a 200 year old, stone built barn.

Do you need plannng permission to put a floor in a barn ? I thought barns were allowed to be built without pp if they had a dirt floor as they were not classed as permanent structures.

For agriculture, you can build a storage shed up to 300 square meters without planning once floor area of all other storage sheds in the farm yard does not exceed 900 square meters. In a domestic house you can build a garage/ store up to 25 square meters with the floor to ridge height not exceeding 4m. An extension to a dwelling house up to 40 ( 12 for a semi-detached) square meters is exempt from planning once its to the rear of the dwelling and ridge height of extension does not exceed existing ridge height.

Edit: There are other regs. governing planning but this is a general breakdown of what can be got away with.
All the above applies to Ireland, don't know about other countries.

 

[Barking Mat]

You don't need to any paperace to put a concrete floor in an existing building possibly unless its listed, for windows and doorway changes you need to apply to the Marie often for a certificate to say you don't need a certificate. Cement mixers are the same size in France as they are in the uk.

 

[Ian X]

Do you need plannng permission to put a floor in a barn ? I thought barns were allowed to be built without pp if they had a dirt floor as they were not classed as permanent structures.

No, its in central France and the mayor is happy for me to keep any building alive. It is over 200 years old and for the last 10 years has stored an old wine press and the swimming pool vacuum.

 

[Ian X]

You don't need to any paperace to put a concrete floor in an existing building possibly unless its listed, for windows and doorway changes you need to apply to the Marie often for a certificate to say you don't need a certificate. Cement mixers are the same size in France as they are in the uk.

Spot on, you know the drill here. Bureaucracy comes first and common sense nearly always prevails. The French countryside will slowly die if common sense where to lose its place.
Mixer size gives me a clue as what might be the order of work, thank you.

 

[Ian X]

I would guess you have roof space to spare, have you thought about leaving the floor and working on top of the hard base you have? Putting a small sloped ramp to the door? I'm not sure what you are doing inside it but I would love a small ramp on my garage to roll cars out haha.

I have plenty of headroom even if I utilise above the beams as upper floor. I had thought of building up but the courtyard between house and barn is pea gravel and I am trying to avoid owning a ramp up into the barn or splurging on 280M2 of paving.
I am hoping for a concrete apron of vehicle size outside of the big door, at the same level of the shop floor and the same level as the gravel court.

 

[Ian X]

I'd give the underfloor insulation a miss too and put the money towards concrete. It's not going to help with the cold in a 200 year old, stone built barn.

After being reminded of what lies under my kitchen tiles here in England I think I agree.
I left an enthusiastic friend in charge of a plate compactor one afternoon. He must have walked several miles around my 20M2 kitchen because when I returned I stared down into what looked like a basement.
I knew the local concrete supplier very well and took my delivery at his convenience which was in fact cheaper than siting another 2T of ballast.
My kitchen floor is 30cm of concrete, it does not get cold with only ceramic tiles over self levelling.

 

[ronan]

Underfloor heating ? You'll never have a better chance to put it in.

 

[addjunkie]

Under floor heating is great we have it right through the house, went through the digging floors out, below walls in a couple of places.

Many tons of new hardcore, whacked down, sand, membrane, 4 inches of concrete, 4 inches of bloody expensive insulation, heating pipes, another thin membrane, expansion edging then another 75 mil of pumped concrete screed. No powerfloating required, great finish. Expensive, but well worth the extra work.

But if you dont put in the insulation youd be wasting your money.

Now if i were adding lots of gravel to a court yard, id put hardcore, then weed membrane, whacked down then the gravel. Or you will be forever adding more till the base is compacted. I use 40 mil crusher run because its about have the price of type 1 subbase, and be advised 20 tons doesnt go far when your trying to alter levels. But it does make a good base. We have had wagons over ours and it barley moved at first now doesnt move at all. Might stick another 100 ton over it in the summer and that should last me till im too old to care. With gravel you also need to contain the edges or it just seems to disapear, with hardcore its not so important.