polystyrene u values, concrete floor

[sm2000]

Hi, I am constructing a concrete floor. Anybody tell me which is cheaper floor insulation is polystyrene cheaper than kingspan , knauf etc? Where I will get its u values? It is a concrete floor: hardcore, cement cent mix, polythene and finally screed. Thanks

 

[Alastairreid]

Hardcore, sand blinding, dpm, insulation, concrete, then screed.

polystyrene is cheapest and rubbish. kingspan, knauf etc much the same price.

 

[mointainwalker]

polystyrene is cheapest and rubbish

Strange comment. Why is that Mr Reid ?

It is a different product with different properties and at a different price.

100 mm of expanded polystyrene has a U value of 0.4

 

[Alastairreid]

100 mm of expanded polystyrene has a U value of 0.4

And thermafloor 0.029 - 0.030 W/mK why compromise.

 

[Alastairreid]

polystyrene is cheapest and rubbish

Strange comment. Why is that Mr Reid ?

I wouldnt use it on a garage floor Mr mointain.

 

[freddiemercurystwin]

polystyrene is cheapest and rubbish

Strange comment. Why is that Mr Reid ?

I wouldnt use it on a garage floor Mr mointain.

Mr mercury is curious as your doubts Mr Reid.

 

[sm2000]

polystyrene is cheapest and rubbish

100 mm of expanded polystyrene has a U value of 0.4

BCO needs at least 0.25W/m2k u value (minimum)!! Any knowledge which thickeness to use? where I can get this information from?

 

[^woody^]

You will normally need polystyrene twice as thick as celotex/kingspan ... 150mm normally for an extension

 

[mointainwalker]

woody

You keep posting that PIR has twice the insulation value of polystyrene and that is wrong. It has 60% more.

Please stop misleading people.

 

[Deluks]

The only downside is that more digging needed and spoil produced. So increased labour/waste costs can sometimes wipe out the saving when using poly.

 

[Norcon]

Kingspan is denser and more solid.
Polystyrene will sink and settle after a few years when load fatigue sets in, with the result of a gap beneath the skirting. I wouldn't take the gift of polystyrene.
No sir'ee.

 

[noseall]

Kingspan is denser and more solid.
Polystyrene will sink and settle after a few years when load fatigue sets in, with the result of a gap beneath the skirting. I wouldn't take the gift of polystyrene.
No sir'ee.

Have you any proof of this load fatigue?

How does this load fatigue manifest? Wholly across the floor or localised at the edges? Is there any cracking of the slab prior to the floor dropping. Why have B.C. or other agencies not condemned it? Does this mean the use of polystyrene with concrete related products should be reviewed?

I have seen gaps under skirting where the skirting board has shrunk just the same as any other timber product - it shrinks across the grain.

At my old gaffers new'ish house the utility room plasterboards were laid directly onto the slab and you could not get a gnats scrotum under the join.
Whereas the skitings are all off the floor by 5mm or more in the same room. All have polystyrene under the floor slab.

 

[Norcon]

I've seen them down 10mm and it wasn't the timber shrinking.
As I said I wouldn't take the gift of it. Give me Kingspan any day.

 

[noseall]

I've seen them down 10mm and it wasn't the timber shrinking.
As I said I wouldn't take the gift of it. Give me Kingspan any day.

Give me Kingspan or Celotex any day but not because of "load fatigue".

I have not seen or heard of this before. Have you any proof or evidence?

 

[Norcon]

If you've never heard of load fatigue then you should get out of the building game.
What else would you put it down too?
Shrinkage?

You add weight. It presses down and through time the polystyrene is compressed.
Either way its a crap product imo. However you like to argue it.
And no doubt you will.