Solid Floor Regulations - Are There Any ?

[UlsterRugby1999]

A neighbour of ours is getting a small barn (attached to his house) floored for conversion to another bedroom and ensuite. The French builder has informed him that the regulations state that he must have a sub floor depth of 200mm. There will also be 100mm insulation and a 50mm screed. Apparently he isnt putting in any hardcore.

Anyone got any thoughts on any aspect of this. My neighbour is worried as the extra cost and potential problems without hardcore are worrying him.

[Gyn_Paul]

Is this to be a poured floor within existing walls (ie. not load-bearing) ?  if so, then it really depends on the state and compaction of the soil.

For mine, I had to grub up an existing stone floor because of headroom and slope issues, then dig out between 75 and 150mm of sub-soil. I then put down a levelling layer of stone (touvenant??) and some grey sand, then ran a compactor over it to get it level. We then poured 100mm of concrete over the DPM onto which will go 90mm of insulation/pipes and about 40mm of screed.

This is the first I've heard of a 'regulation' 200mm. Seems rather excessive if the heavyest point load is going to be a wardrobe. No so if there are load-bearing walls to be built on it (parition bathroom walls don't count).

He could split the difference and have 100 mm of hardcore and 100mm of concrete, but by the time he's paid for the hardcore, hire of the compactor, and the labour, it's probably much the same price as the other 100mm of concrete.

p

[UlsterRugby1999]

Cheers P - thats more or less what I though too. The load bearings are already catered for by the existing walls so its nothing to do with that I believe and anyhow, surely if a load bearing wall was being added it would go on top of a specifically calculated foundation rather than just a floor. The other issue I though of if he went with 200mm of concrete is the additional drying time, especially given our horrible weather right now. Surely the extra depth would take much longer to dry and prevent him looking at floor finishings.

[AnOther]

I didn't think France "did" building regs, at least not for existing properties [blink]

It was said here somewhere very recently that within a property you did pretty much what you wanted.

If this is not the case then I'd imagine 90% of DIY renovations could well be illegitimate [:-))]

[powerdesal]

No doubt someone will correct me if I am wrong but concrete doesn't actually dry, it cures. Its a chemical reaction that is homogeonous throughout the mix. Strickly speaking full strength will be in 28 days but you should be ok after 7 ish. Its hot weather that you need to beware of for concrete as you must not let the surface dry off too quickly or you will get cracking.

I await comments from an expert.

[Gyn_Paul]

Somewhere I've seen a web page with a formula for how long various thicknesses take to cure completely, I thought I'd bookmarked it but apparently not.

This was a matter of concern to me too. So much so that I argued with my builder as to the merits of putting the DPM on top or below the poured concrete. Received wisdom is that it goes between the sand (or hardcore) and the concrete. But then if you are going to put sheets of impervious insulation on top of it, then how's the water going to get out?

I was answered with a grade #1 Artisan's shrug, of course, so I'm no further forward.

In the event we put it underneath, and it's been set for ages and I still haven't got round to putting the polystyrene forms for the pipework on top (van troubles) so it will, by default, be dry by the time it's eventually covered up, but I STILL think the water would leech out into the subsoil just as easily, frankly.

Given that it's not load bearing, then once it's gone off (couple or three days) he can get on with the business of putting the insulation on it. The water will find its way out by hook or by crook, it seems.

Yes, If it's to have walls on it then a cross-section through the floor should look like a cross-section of a low coffee table: deep footing (with box rebar) flowing into a concrete slab (reinforced with cross-section mesh - 100mm from memory) and the same on the other side.

p

[Gyn_Paul]

[quote user="powerdesal"]No doubt someone will correct me if I am wrong but concrete doesn't actually dry, it cures. Its a chemical reaction that is homogeonous throughout the mix. Strickly speaking full strength will be in 28 days but you should be ok after 7 ish. Its hot weather that you need to beware of for concrete as you must not let the surface dry off too quickly or you will get cracking.

I await comments from an expert.

[/quote]

Cures. Right

Chemical reaction. Absolutely.

Except that it starts off wet, and in the process of the chemical reaction it releases water, and ends up firm and dry to the touch. So ermmm... I'd call that 'drying' within the meaning of the act, wouldn't you ? [8-)]

p

[Albert the InfoGipsy]

Actually France does have loads of building normes, but no organisation like UK 'Building Control' to enforce them. The approach seems to be that if a job isn't done according to normes then it'll probably fail within 10 years & you can make a claim.

The requirements for foundations and floor slabs also vary across the country for two reasons: frost depth and seismic risk.

[UlsterRugby1999]

Mother in Heaven - we have a science lesson on the go. Just kidding folks.

Do any of you ultra wise folks have a link to any sites that actually show these French regulations - as described above.

[AnOther]

Hard to claim against ones self [:D]

Is it not the case though that, theoreticaly at least, ALL work done should be guaranteed for 10 years ergo even that DIY renovation you did and sold on the buyer can claim against you if something goes wrong ?

Back to concerete and I seem to remember reading a long time ago that it never stops curing and according to THIS site:

"If concrete sets in

one day, it will be more than four times as hard after a week, six

times as hard in a month, and more than eight times as hard after five

years"

what then after 10, years, 20, 50 etc.

Finally, if you fancy some scintillating bedtime reading [geek]

[strebor]

I think that many new floors are now built block and beam over a vide sanitaire.

Even for renovation where planning is invoked, certainly our new build is block and beam with the blocks being made of polystyrene.....m

[strebor]

ErnieY, that article was interesting if a bit over my head. Did once see a coil spring made of concrete and it flexed about 30%...m

[powerdesal]

[quote user="Gyn_Paul"][quote user="powerdesal"]No doubt someone will correct me if I am wrong but concrete doesn't actually dry, it cures. Its a chemical reaction that is homogeonous throughout the mix. Strickly speaking full strength will be in 28 days but you should be ok after 7 ish. Its hot weather that you need to beware of for concrete as you must not let the surface dry off too quickly or you will get cracking.

I await comments from an expert.

[/quote]

Cures. Right

Chemical reaction. Absolutely.

Except that it starts off wet, and in the process of the chemical reaction it releases water, and ends up firm and dry to the touch. So ermmm... I'd call that 'drying' within the meaning of the act, wouldn't you ? [8-)]

p

[/quote]

A quote from Ernies bedtime reading     "The setting of cement is not, as sometimes

believed, a drying process; in fact, it

is the exact opposite."

I have my excuse for lack of knowledge, I am NOT a Civil Engineer. Gas Turbines and Desalination plants are my thing.  I read part of the paper Ernie and it really lost me.

[UlsterRugby1999]

It just couldnt stay simple - could it. Mudder O God ErnieY - where are you going with this. [:D]

Okay - so I take it that he should stuff the hardcore, sand cement and aggregate and just build the floor in sand like a sand castle - is that it [8-)][8-)]

[Gyn_Paul]

[quote user="powerdesal"][quote user="Gyn_Paul"][quote user="powerdesal"]No doubt someone will correct me if I am wrong but concrete doesn't actually dry, it cures. Its a chemical reaction that is homogeonous throughout the mix. Strickly speaking full strength will be in 28 days but you should be ok after 7 ish. Its hot weather that you need to beware of for concrete as you must not let the surface dry off too quickly or you will get cracking.

I await comments from an expert.

[/quote]

Cures. Right

Chemical reaction. Absolutely.

Except that it starts off wet, and in the process of the chemical reaction it releases water, and ends up firm and dry to the touch. So ermmm... I'd call that 'drying' within the meaning of the act, wouldn't you ? [8-)]

p

[/quote]

A quote from Ernies bedtime reading     "The setting of cement is not, as sometimes

believed, a drying process; in fact, it

is the exact opposite."

I have my excuse for lack of knowledge, I am NOT a Civil Engineer. Gas Turbines and Desalination plants are my thing.  I read part of the paper Ernie and it really lost me.

[/quote]

I hung on as far as "... These composite layers stack along the [001] direction, separated by water molecules, Ca2+ ions, and possibly OH– ions." before my eyes started to glaze over and my chin hit my chest. He's right about it being bedtime reading!

OK, it's not drying in

the same sense as - say - a  liquid glue, where the cross-bonds already

exist in the solution, and as the water evaporates, they shrink and tighten. And,

yes, water is incorporated (and goes on being incorporated) into the crystaline structure as it sets, but that presupposes that all the water stays trapped within the matrix. If that were the case then my 200mm x 4000mm x 4500mm concrete floor, poured the 1st week in April, which then had plasterboard walls added the following week, and a lambris ceiling the week after and which was then left closed up for 2 months, would have been nice and clean and dry when I got back, rather than every surface sporting a new and interesting collection of black and green mold. Exactly the same mold you get behind tiles on a leaking shower. Ugh!

p

p

[Gyn_Paul]

[quote user="powerdesal"][quote user="Gyn_Paul"][quote user="powerdesal"]No doubt someone will correct me if I am wrong but concrete doesn't actually dry, it cures. Its a chemical reaction that is homogeonous throughout the mix. Strickly speaking full strength will be in 28 days but you should be ok after 7 ish. Its hot weather that you need to beware of for concrete as you must not let the surface dry off too quickly or you will get cracking.

I await comments from an expert.

[/quote]

Cures. Right

Chemical reaction. Absolutely.

Except that it starts off wet, and in the process of the chemical reaction it releases water, and ends up firm and dry to the touch. So ermmm... I'd call that 'drying' within the meaning of the act, wouldn't you ? [8-)]

p

[/quote]

A quote from Ernies bedtime reading     "The setting of cement is not, as sometimes

believed, a drying process; in fact, it

is the exact opposite."

I have my excuse for lack of knowledge, I am NOT a Civil Engineer. Gas Turbines and Desalination plants are my thing.  I read part of the paper Ernie and it really lost me.

[/quote]

I hung on as far as "... These composite layers stack along the [001] direction, separated by water molecules, Ca2+ ions, and possibly OH– ions." before my eyes started to glaze over and my chin hit my chest. He's right about it being bedtime reading!

OK, it's not drying in

the same sense as - say - a  liquid glue, where the cross-bonds already

exist in the solution, and as the water evaporates, they shrink and tighten. And,

yes, water is incorporated (and goes on being incorporated) into the crystaline structure as it sets, but that presupposes that all the water stays trapped within the matrix. If that were the case then my 200mm x 4000mm x 4500mm concrete floor, poured the 1st week in April, which then had plasterboard walls added the following week, and a lambris ceiling the week after and which was then left closed up for 2 months, would have been nice and clean and dry when I got back, rather than every surface sporting a new and interesting collection of black and green mold. Exactly the same mold you get behind tiles on a leaking shower. Ugh!

p

p