Not forgetting that aggregate works better with a cement as bonding agent 
But still works out cheaper that ready mixed although the labour content is much higher.
Personally give me ready mix every time and a pump if nessasary.
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Thanks for advice everyone, the cellar is a basement that opens to a full length balcon,y on one side, as it’s on a mountain, and there’s a window i can keep ajar for ventialtion, and also considered a dehumidifier. I have lots of vinyl records and my painting to put there too. {erhaps a compris de vente
Hi, This sounds really amazing, i have a house I want to buy up in the mountains and downsize and retire from the UK, and it’s stone built so when I saw it last July was cool inside despite heat outside, don’t want air conditioning if possible. The ground floor be good to live on, the semi basement, opening with a window onto a balcony, I wanted to store my huge collection of boks, vinyl records, and my own painings. The attic with very sloping roof will be my art studio, and I’ll give free workshops as i can’t work on teh retirement VTS. I’m just hoping it won’t sell before my exchange, and i have a surveyor RIC preped to visit as soon as possible. I understand i can’t do subject to survey in France, so just have to do before compris de vente. Many thanks, this is a wonderful cheaper soloution
I know this is very late on getting in on this discussion ..but why a concrete floor ?. The traditional build would be a suspended timber floor with an air space below and air brinks or vents to protect from rising damp. Traditionally the ground would have been just clay excavated to a level which allowed enough air circulation and timber joints set at the appropriate height…and a tongue and grooved platform on top… Oak if a certain standard demanded and Pine otherwise. ..But depending on the intended lifetime and floor covering even plywood or aggro…
Those of us who renovate a retirement nest are not building a forever structure ..which a massive concrete floor is .
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Not sure what kind of buildings the OP had but in many cases (eg barns) there’s not enough height for a suspended floor. Also many barns have quite shallow stone foundations and deep excavation is risky.
In my own barn we laid ( 18 years ago ) a lime cement and insulation 180mm wide margin to the new reinforced and insulated cement floor and it is dry even though one end is below ground level and there is no tanking, just lime plastered wall (and mud render outside). We laid it originally as a workshop floor so used cement, though I have converted half of it to living space now.
PS as a carpenter I would always use timber where I can…
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It’s about time the suspended timber floor was laid to rest. Even listening to a talk by an architect just the other day, he removed his drafty cold vented floor and screeded it then fitted 700mm of insulation which tapered to 250mm at the other end of his house. He did plenty of other enerfit mods.
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Ventilation will not protect from rising damp, rising damp is due to capillary action in a substrate, such as cement or stone walls built without a damp proof course.
The bearers in suspended wooden floors will eventually rot as passive air vents alone wont give sufficient ventilation
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Yes it’s problematic when timber close to the ground needs ventilation and insulation is also required which blocks ventilation.
I had an old townhouse in Guernsey where the joists were just laid on the earth. This was below outside ground level which had been built up with successive overlayings of slabs etc. No possibility of venting. The telltale was rusting evident on modern nails holding the floorboards to the joists which had been renewed by the previous owner. They used old greenhouse roof timbers, you found that a lot in Guernsey. Gash job. I ripped it all out and replaced the floor with concrete. Also reduced the ground level outside to what it had originally been. An electro-osmotic dpc was fitted to the stone walls and replastered. It was all reasonably dry after all that. We fitted a reclaimed pitch pine floor on battens over the concrete. I always used battens, never glued boards to substrates.
My knees know about timber flooring…
There was a big boulder in the earth floor, which stayed there 
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If it takes 30 +years for that rot to happen ..does it matter?. Nothing lasts forever. .. The next owner has the option of removing the new ..now rotted beams and replace them . . .. . However who says there should not a damp proof membrane inserted below any wall plates .and over the clay? . Also the void below the floor is not as deep as expected … 15 cm is a typical minimum …so whether that would cause lateral movement of the walls by undermining foundations will depend on the situation
Now I am not going to argue this point further .. I choose to open another viable option ,which can suit some cases ..and not in others..
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That is very gratifying.
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I restored an Edwardian house in Nottingham which had timber floors throughout apart from the kitchen and an add-on toilet/washroom groundfloor builder’s afterthought/original developer’s promotional wheeze. They were all over a cellar with brick dpc and were 99% sound. The places which weren’t sound were the kitchen and toilet. The foundations were shallower there and needed underpinning.
When I had it rewired the electrician vandalised those joists. I had to go off fishing on the Trent when he was working, it broke my heart what he did to them (and his brickwork drilling).
Upstairs I repaired a lot of the original floorboards that had been vandalised by the plumbers. I found some beautifully-cut entries into the floorboarding (inch and one eighth) mitred in and perfect after 100 years over the original lightfittings made by the first electricians. Under the boards I found a newspaper cutting from the Nottingham Post of a flight by the Wright bros…
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As a matter of interest what are the other tasks you were thinking of?
The quote for flooring maybe could be cheaper but what you’ve got as a quote does not sound unfair. And you’ve had the enormous advantage of seeeing his work and him having a local reputation to maintain
Flooring being quite important it would be nice to get it out of the way even if other things might take time to sort. I guess you have maybe roofing and a rewlre / plumb as well?)
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Our London house is built on a concrete raft rather than direct to earth. I will have to replace some more floor joists soon as there is quite a bounce occurring. I have temp and humidity sensors under the floor to monitor actual moisture levels. I am not very convinced of open air bricks being a sufficient system for proper ventilation. Last year to conserve some heat (bare sanded floorboards) I tapped over the air vents to watch the results from the sensors. For the most part of stayed dryer down there than when the air bricks were open as the unchecked air entering the void was almost always more moist.
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“The bearers in suspended wooden floors will eventually rot as passive air vents alone wont give sufficient ventilation” ..
My parents house built 1910 ( Edwardian has suspended timber floors over clay and with the air bricks No concrete rafts then ..There had been no rotting of timber up to at least 1985 , when my mother sold it .. In the 1950s , I used to follow the house cat under the ground floor rooms.
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It’s horses for (damp proof) courses. Not much common to old barns. Edwardian houses are lovely to look at and character-forming to live in, during what we used to experience as winter in the Midlands in the 60’s. Hot in August too…
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A friend was quote €5000 here in the Ariege for maybe a 4 x 4 m space. There was slightly difficult access too. I decided to help him with one other, mixing in the basement with a cement mixer and me carrying up two flights of stairs bucket by bucket. We collected several trailers of sand, cement and aggregate. We did it in a long day and materials came in under €1000 (i was told) . Saying that we did all this labouring for free. Exhausting work, but saved a lot of money
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Good afternoon to all.
I’ve had numerous replies to my original query - all useful and interesting.
There were loads of other jobs planned - insulation, electrics, adding new bedroom …
Removing the flooring from one barn room resulted in dropping through a bit of rotten floor and two broken ribs … talk about laughing - I nearly did !
A re-evaluation of costing showed an un-recoverable amount if we were to sell … and I had to be realistic about ability and age … I’m a competent diy-er and well experienced in electrics (ex merchant navy - fair amount of wiring and 6KV systems).
I’m quite fit but 77 is a good age to slow down…
We finally decided, sadly, to move somewhere needing less work.
We hunted and finally found a lovely place near Pontivy - original build in 1842 and lovingly refurbished by a french owner then by an english family.
Unfortunately , there was a fire four years ago but the insurance paid out for a new roof, new kitchen, new insulation, and total re-wiring.
Actually no big jobs to do but there’s enough cheap and cheerful diy to keep me going and a 1600 sm wooded garden to play with.
Again, my thanks for all the valuable comments… I’m sure I’ll be back for more help.
Cheers
Peter
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Must have been the fall knocking some sense into you 
. Well done on re evaluation and may I say, the correct decision, we have mostly done our much smaller places but still have some things to do. I intend to put down my tools in two years time.
Pontivy and environs are a good location ..Good medical services and bus services into Rennes or Lorient / Vannes and these supply excellent trains to Paris etc. Pontivy is sufficiently inland not to be crippled by seaside prices , and yet is still only 40 minutes by easy roads to the coast.
2hours, every 2 hours approx so ok if travelling onwards but not for a city day out.