MBC slab pour in north Dorset

[vivienz]

MBC are currently scheduled to pour my slab next Tuesday, no idea what time yet.  If anyone would like to come along, let me know. 

 

There are details on my BH blog of today's work on the slab with some photos of progress.

[lizzie]

I would watch them very carefully and have your level at the ready to check it

[vivienz]

Yes, indeed, Lizzie.  It was you I had in mind when having my word with them this morning.  I admire you in many ways, but have no desire to emulate your slab experience.  I'm sure you understand.

[lizzie]

21 minutes ago, vivienz said:

Yes, indeed, Lizzie.  It was you I had in mind when having my word with them this morning.  I admire you in many ways, but have no desire to emulate your slab experience.  I'm sure you understand.

I do understand and I have no wish for you to go through that hell.....just looked at your blog.......when checking levels dont just check where walls go check the whole thing we had dips and humps all over.  A simple check is some water and if you get lakes (like us) then its very evident.  Not sure if you can do water on wet slab though.  Ours showed from rain the following day.  

[willbish]

12 hours ago, vivienz said:

If anyone would like to come along, let me know. 

If this goes back to Thursday, I would like a gander if that's okay please. 

[Onoff]

Is it feasible to stick a concrete poker in these mbc slabs upon pouring? I've read a few horror stories of them not coming out level.

[PeterW]

Poker won’t level a slab - it needs to be tamped and probably power floated to get it flat. Self compacting concrete levels itself to a point but you can still make it have an overall “slope” as it’s nowhere near fluid enough to truly level. 

[Jeremy Harris]

12 hours ago, Onoff said:

Is it feasible to stick a concrete poker in these mbc slabs upon pouring? I've read a few horror stories of them not coming out level.

 

I know of two, out of several dozen that I know of that have been poured (there may well be a lot more), where the slab wasn't flat and level.  One was a case of a new sub-contractors first ever job, who wasn't aware of the tolerance requirement, and the problems were remedied.  Not sure about the cause or outcome for the other one.

 

Take ours as a typical example, bearing in mind that our build was, I think, only the fourth or fifth UK passive slab they had laid.  The concrete was poured and vibrated with a poker to get the concrete around all the rebar.  It was then levelled with a long trammel and tamped, then left a while to partially cure.  It was then power floated for ages to get the surface both level and smooth.  The slab surface was so level and smooth that I could lay flooring directly to it, and ended up with loads of bags of tile cement left over, as the tile cement estimating tool assumes a degree of floor unevenness that will use up more adhesive.  Our tiler couldn't not find the highest point on our slab from which to reference his tile height, as after 40 minutes wandering around with his laser level he concluded the slab was dead level and flat, so he could start wherever was easiest.