Scrapping power floated floor and going conventional slab

[flanagaj]

Having been unable to find anyone who seems half interested in doing our specified power floated floors, we have decided to go with a conventional ground supported slab build up with the insulation on top of the reinforced concrete slab.  I decided to go with 150mm insulation on top of the slab simply because I didn't want to have the really long warm up times I'd get if I had a 150mm slab with a 70mm screed layer on top.

Can anyone explain or show a diagram which details how the screed layer, inner block leaf and PIR come together at the door reveals when you have a level threshold.  Does the PIR simply protrude into the reveal and mate up against the internal face of the outer brick leaf?

[Russell griffiths]

Change the pir out for xps insulation in the door area, look for one with a high compression something like xps 500. 
you have a cavity build up so will be a bit different to mine, but basically leave the inner blockwork low, fill your cavity with whatever you are doing and set the xps down solid onto this lower structure, doors sit on that, with whatever dpc you deam necessary 

don’t use 150 mm insulation, get 75mm and do two layers. Easier to cut and you can stagger the joints. 
 

 

[flanagaj]

13 minutes ago, Russell griffiths said:

Change the pir out for xps insulation in the door area, look for one with a high compression something like xps 500. 
you have a cavity build up so will be a bit different to mine, but basically leave the inner blockwork low, fill your cavity with whatever you are doing and set the xps down solid onto this lower structure, doors sit on that, with whatever dpc you deam necessary 

don’t use 150 mm insulation, get 75mm and do two layers. Easier to cut and you can stagger the joints. 

Ok, thanks.  I didn't consider using two layers of 75mm instead of a single 150mm layer.  I can see that by staggering the joints, you negate any potential cold spots where the insulation butts up together.

[Mike]

2 hours ago, flanagaj said:

I didn't consider using two layers of 75mm instead of a single 150mm layer.

2 layers is definitely a good idea.

 

If you have a nearby installer, sprayed high-density PU foam is another option that's very common here in France. For example https://www.youtube.com/watch?v=CSZ2Mhtbq_M

 

[Nickfromwales]

4 hours ago, flanagaj said:

Having been unable to find anyone who seems half interested in doing our specified power floated floors

You could just use self compacting / levelling concrete. Completely negates power floating altogether.

[saveasteading]

1 hour ago, Nickfromwales said:

Completely negates power floating altogether.

Is that assuming another finish will cover it? eg  carpet/ tiling?

I've never seen it but have seen the ripples in flowing screed.

 

I've looked up the blurb and it seems to mention mainly that it flows around reinforcement and complex shapes. Flooring is mentioned less, and one 

reference said suitable for domestic (implying only domestic?) and that it doesn't need a screed over it.

 

It's surprisingly difficult to find out more, especially technical stuff about strength and surface tolerances.

any references would be welcome as I dont like to not know this sort of thing.

@Nickfromwales presumably you've used it. Is it like  screed finish? What cost relative to old fashioned pump mix?

 

[Nickfromwales]

3 hours ago, saveasteading said:

Is that assuming another finish will cover it? eg  carpet/ tiling?

I've never seen it but have seen the ripples in flowing screed.

 

I've looked up the blurb and it seems to mention mainly that it flows around reinforcement and complex shapes. Flooring is mentioned less, and one 

reference said suitable for domestic (implying only domestic?) and that it doesn't need a screed over it.

 

It's surprisingly difficult to find out more, especially technical stuff about strength and surface tolerances.

any references would be welcome as I dont like to not know this sort of thing.

@Nickfromwales presumably you've used it. Is it like  screed finish? What cost relative to old fashioned pump mix?

 

It's fortuitous timing, as I've literally just witnessed an MBC pour where this was used, and it went well. Went to site to collect some of my stuff and the pump truck was just setting up! I stayed for the spectacle out of curiosity more than anything (plus I am sad so like that kind of thing lol).

 

It was quite a thin 10mm aggregate mix, quite free-flowing up until one not-so (mix but last), and then all it needed was raking out and hand placing to within 3mm with the laser, and then a 6' dapple bar to get it to settle in it's final resting place. Finish was much like an SLC, and as the chap was dappling it, another leaned over him and sprayed a Sika sealer over it; this acts like a layer of cling film to stop moisture being released too quickly.

 

Cost-wise, MBC asked no more money for it, but they avoided having to power-float so I doubt the difference was worth any proper quibbling over. Cemex provide the goop, so maybe check in with them if you require the nerdy stuff like additives and so on. We looked it over after the pour and noted it had fibres in it.

 

It's due to have 3-5mm of SLC / feathering compound to then accept LVT (Kardean / Amtico or some such) and I doubt this will need much attention at all after these guys did their thing. As with anything, the right guys will do a great job, cheap guys will do shit jobs, and you then have to pay to put it right. These guys made it look easy tbh.

[Nickfromwales]

3 hours ago, saveasteading said:

Is that assuming another finish will cover it? eg  carpet/ tiling?

I've never seen it but have seen the ripples in flowing screed.

Even with an excellent power floater, nothing is good enough for a domestic setting imho. Bare concrete will always be bare concrete, and as it has no shine / sheen the unevenness is masked from any untrained eye.