Laying a concrete floor

pmartin86

Evening All

Basically I had damp in my downstairs suspended wooden floor and it had to be removed, this has now been done, and all areas have been treated, walls stripped back etc.

I want a concrete floor to match the rest of the downstairs (this was the only remaining suspended floor), and I've had enough of trying to chase don a builder who wants the job. Having watched the living floor get done with the same process about a year ago, I've got a solid grasp of whats needed and I'm tempted to DIY it. I've already dug down and put in 200mm of compacted hardcore as a base, followed by 50mm of sand. I've got 100mm insulation boards to go in also. Basically, i just need advice on the last bits,

1. Does the DPC go above or below the Insulation boards? In the living room its above, but advice Ive has says below?

2. I will have roughly 125mm left after insulation and DPC, would concrete to the top be sufficient? I plan to tile the floor afterwards, or should I stick to 100mm of concrete and 25mm screed?

3. If I hire a cement mixer, how long would this likely take me? I'm fairly fit and would have a helping hand to load the mixer. The room is approx 4m x 4m I've got some TOIL owed to me, and was thinking a full weekend plus 2 days TOIL should be enough, I can have help for the 2 days on the weekend, is this realistic?

Regards
Paul

ceredigion

Two DPM's, one above and one below the insulation. You have got to pour it in a day. Don't forget the vertical insulation (25mm) to stop the cold bridge

cyclonebri1

You do not need 2 DPCs

Put the poly under the polystyrene, for any reasonable sized room 100mm concrete is perfect, 125mm even better. Get your concrete guy to add fibres, sound him out on that, it will stop/reduce cracking

No screed, solid concrete. Get the top as perfect as poss then simply use thick bed adhesive at about 10mm thickness

PS to explain, modern tech means adding fibreglass fibre greatly increases crack resistance and tensile strength

Paradigm

4M x 4M x 100mm is around 1.5 cubic metres, about 2 tonnes give or take a bit.
You're going to struggle to mix that & lay it in a day.
I'd be looking at readymix & lots of wheelbarrows.

heretohelp

Try phoning the concrete companies up they will either have its own laying team or a list of contractors.
The last time I used one they did a 4m x 12m room in about 2hrs everything was prepaired it was just the concrete they layed.

ceredigion

cyclonebri1 wrote: »

You do not need 2 DPCs

Put the poly under the polystyrene,

You tell that to my building control officer and how do you offset problems with the dew point.

cyclonebri1

ceredigion wrote: »

You tell that to my building control officer and how do you offset problems with the dew point.

I simply don't see how that comes into it, if you are saying that the room temp will be so low that "dew" forms and will be drawn into the concrete then there ventilation and heating issues.

In effect the polythene is 1 dpc and the foil on the polystyrene the 2nd.

Can't find anything in building regs that dictates otherwise.

http://www.diydoctor.org.uk/projects/underslabinsulation.htm

cyclonebri1

Paradigm wrote: »

4M x 4M x 100mm is around 1.5 cubic metres, about 2 tonnes give or take a bit.
You're going to struggle to mix that & lay it in a day.
I'd be looking at readymix & lots of wheelbarrows.

To be honest with 2 fit blokes it's quite, easy, but the mixing will hold things back if the barrow run isn't too far.

To be fair it is the max for 1 day, would likely take about 5 hrs to mix, then the final levelling.

Other issue is the cost saving, especially if you have to hire a mixer will be zero, but you have all the effort, I too would go with ready mix for anything over 1 cu mtr