Laying a smooth concrete floor

[LisaContractorUmbrella]

What flooring are you planning on putting down once the job's finished?

[Fandango]

I've laid a large concrete base before and had it floated (machine polished)

tbh if you want a perfectly level based I'd go with a lorry poured self levelling compound/screed, floating the floor gets it smooth but won't necessarily get it level.

with a self levelling compound you'd line the room with a damp proof membrane sheet and fill it to the desired level, a little bit of tamping here and there and voila! there really isn't that much to it.

https://www.youtube.com/watch?v=RZswb0_CNXY

http://www.flowscreedingservices.co.uk/installation/

[OwlHoot]

What flooring are you planning on putting down once the job's finished?

Carpet underlay then carpet

(and any other layers needed above the concrete for a carpet, although I don't think any are)

[Bacchus]

As others have said, a self levelling screed should do the job quite easily, but you will need to hire a massive vibrator like these.

[suityou01]

Piece of piss Owly. Crack on.

[BrilloPad]

Lay least favourite CUK posters on floor. Cover with concrete.

If MF there will be no flat finish.

[Bunk]

Lay least favourite CUK posters on floor. Cover with concrete.

If MF there will be no flat finish.

Has anyone seen Mordac?

[vetran]

concrete doesn't tend to leak unless its very wet or the shuttering is very poorly supported.

Lay dryish near the edge, build up slowly ish. support shuttering with bricks at right angles or concrete blocks.

[xoggoth]

Opens Readers Digest DIY Manual for about the second time in the 20 years I've had it.

1 Make sure floor is not damp, if it's pre 1940 it may not have a damp proof membrane and damp will eventually ruin any surface you lay. If it is damp, remove any dust/dirt and repair any cracks with cement. Dry as much as possible with a fan heater and use 3 coats of moisture curing polyurethane sealant, allowing each to become touch dry before next. Scatter dry sand over the final coat before it dries.

2 If step 1 is not required, fill any significant indentations with sand and mortar mix. First brush with PVA adhesive and add a little to the mortar. When dry, clean floor with sugar soap and water. Rinse and allow to dry thoroughly.

3) Finish with a self levelling compound - very runny so levels itself. Follow mixing instructions on packet. Spread with a trowel to minimum depth of about 1cm or as needed to fill in any dips. It hardens very quickly, about 1 hour, but see instructions on packet before walking on it.

[OwlHoot]

Now I'm thinking if the floor needs concreting then I may as well first lay pipes for underfloor heating.

Even if these are capped off and not used for now, or ever by me, they might be a good selling point in future.

But presumably that means the concrete must be significantly deeper, and the pipes and labour of installing them would add a fair bit to the cost.

Does that sound like a good idea or is underfloor heating overrated and a bit of a gimmick?