Block and beam floor insulation with restrictive height

[DeanAlan]

Hi all,

 

The renovation and extension project we are working on is approaching the stage where I have to lock in the height of a large set of sliding glass doors to the garden and floor level for the liquid screed pour and the block&bean is a little high in one area that is causing me some struggles.

 

Primary issue is that about an area of around 2.5m x 5.5m (13.75sqm) is around 12mm higher than the other 90 sqm. That doesn't feel like much BUT we have a pretty tight margin. The plasterboard ceiling will be 2,559mm above the block and beam elsewhere giving me room for 100mm insulation, 55m liquid screed and 4mm decorative floor finish leaving 2,400mm to ceiling.

 

However, if I work from the high area then if I use the same buildup of 100mm insulation, 55m screed and 4mm finish then I would have a 2,388mm heigh ceiling and in general a lot more than 55m screed for 90% of the floor areas (more like, 67mm which costs more and I loose ceiling height).

 

I'm wondering whether I should use 90mm insulation in this area of the floor and 100mm elsewhere or put 100mm insulation everywhere and allow the screed to be more like 43mm in the high area. Thoughts?

 

The other concern I have is that the blocks sit 2-4mm below the top of the concrete beams which surprised me. I though the block were designed to sit flush with the beam tops - all from the same block and beam floor provider (they will remain nameless for the moment) and not cheap! If I lay insulation board across this then what will happen with the void they span between beams? Should I - for example - put some sand down to level it all out? When they first laid the block and beam they then put the grouting slurry down and it all seemed level but it didn't take long for some rain to wash away the top surface. Should that surface have been more resilient, should I have expected the blocks to have been level with the beam tops? Should I go complain heavily about to the beam installer? Should I sand of lay some filler concrete slurry surface to make it all level before I put insulation boards down?

 

cheers,

- Dean 

[Russell griffiths]

Mix up another load of slurry, pour it on and level it out, fit 90mm of insulation and don’t tell anybody. 

[DeanAlan]

Sounds about right @Russell griffiths!

I might use 100mm where I can and then drop to 90mm in the offending area.

[Russell griffiths]

48 minutes ago, DeanAlan said:

Sounds about right @Russell griffiths!

I might use 100mm where I can and then drop to 90mm in the offending area.

That’s what I meant really. 

[Mr Punter]

You may want to work out where the thinner stuff is going and build a 10mm step around the perimeter with levelling compound.  Make sure it works with the sheet sizes.  Bear in mind the beams tend to have an upward camber.  Blocks are often only 95mm.