Got some guys coming in next week to fix the basement; they’re finishing up by pouring self-levelling concrete over the existing tatty concrete floor. Sounds like it’ll only be a couple of cms deep.

Anyway, I have the missus wanting a ‘polished’ look when it’s all cured; is there anything I should be asking the guys up front to do that would help? Or is it just a case of letting them do their thing, and then finding a good hardwearing sealant to fix it up myself?

If you want to polish the floor be aware that there is a ideal window when the concrete will be hard enough but not too hard, probably it will be at about 5 – 8 days unless they have any additive that effect set time. Try a small area if you find you are pulling too much fine sand out as you polish give it a bit longer.

Stop polishing at about 400 grit to give whatever sealer you are putting on something of a key.

20 mm of concrete will crack the day after its laid. are you thinking of self leveling compound? if so you can’t polish self leveling. make sure all loose stuff, dust, old plaster is scrupulously removed hoovered, then make sure its given a good coat of pva first, which is then left to dry before pouring self leveling. self leveling isn’t really hard enough to be a finish, its more to do with preparing for lino, carpet, laminate or tiles etc.

Are they using a proper concrete screed or a Anhydrite screed, concretes not really suitable below about 70mm

If the floor really is a couple of centimetres thick, it’s more likely to be some sort of self levelling screed. If so, the finish will not be hardwearing or particularity good (it’s designed to be covered – carpets/ vinyl etc)

If it really is concrete, ask for the floor to power floated.(It’s not a DIY type job and can take all night to get right)

If you want it to look like a warehouse floor they’ll need to add ‘dry shake’ to the wet concrete – this is getting into quite specialist territory though.

Ah, good job I asked the stw experts.
Based on what you’ve said, sounds like it’s going to be self-levelling compound/ screed, not concrete proper.

We hadn’t been planning to do anything more to the floor (carpet, tiles etc) just yet, until we work out what to do with the walls etc, maybe next summer. In the meantime, what’s best to be done with it? Can I do anything to make it more resilient/ hardwearing?

if you don’t need it doing yet why are you having it done? i’d be doing any remedial work to the walls ie damp proofing first, then electrics etc, plastering then self leveling at the end once i’d decided on a floor finish…

If it’s poured Anhydrite screed it’ll quite soft and very dusty, ditto self levelling to be honest, neither is suitable for a surface finish. At 20mm think it WON’T be concrete, the thinnest I’d ever be happy having a screed at is 50mm, any less and it will crack/ curl up.

Be careful what you put over the screed afterwards as a temp. if you want anything glued to it eventually (tiles etc.) you down want anything that later down the line will stop the adhesive from gripping.

Sort the walls out first. Speaks the man living in a money pit/squat…… 😀

spchantler: we’re getting the walls damp proofed, weeping tile, then this stuff to level the tatty floor (damaged by years of rising damp).

But in terms of actual finishing (drywall, painting etc), that will probably come, but not right away. It’s mainly a financial thing!
Because they’d said “self levelling concrete”, I’d taken that to mean actual concrete, for which sealing and perhaps painting would be an option – as per the garage floor thread from earlier this week.

If you ever want to tile it, do not use garage floor paint on it. it would all have to be removed mechanically before tiling could commence in the future.

also, remember to leave whatever is put down to dry properly before flooring/sealing of any type. 1 day per mm of screed thickness.

(damaged by years of rising damp)

I would suggest you sort this out first if you spending money on doing walls etc.

If they said concrete its concrete surely. Not a latex/cement based self leveller.