polystyrene u values, concrete floor

[noseall]

....erm, what sort of weight are we talking about here Norcon?

Would it be fair to say that a washing machine that has been in the same corner location for more than 5 years cause some degree of load fatigue?

In which case, the plaster boards (which were laid on top of the screed) as well as the skirting board should have at least a millimeter or so of gap?

How long does this fatigue take to set in?

 

[freddiemercurystwin]

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

You know you'll have a long wait nose!

 

[^woody^]

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.

The thing is, polystyrene is not sold in random thicknesses, so as 80mm of PIR/PUR is normally required then the equivalent thickness of polystyrene would be a 150mm sheet .... which coincidentally is about twice as thick

 

[mointainwalker]

so as 80mm of PIR/PUR is normally required then the equivalent thickness of polystyrene would be a 150mm sheet ...

You just can't stop doing it , can you ?

The equivalent is not 150 mm but 130 mm.

Do your bits of timber or piping runs often end up the wrong length because the maths has gone a bit wonky ?

 

[^woody^]

But you can't buy 130mm of polystyrene, so the OP needs to buy 150mm thick boards

 

[joe-90]

Woody delivers the knock-out blow. There's no coming back from that one.

 

[freddiemercurystwin]

 

[mointainwalker]

But you can't buy 130mm of polystyrene, so the OP needs to buy 150mm thick board

80 +50 or 70 +60 or 100+ 30 ?????????????

 

[noseall]

Recent spec's have been asking for 125mm jablite which would consist of 100mm + 25mm.
However, fitting the 25mm layer can be a pain in the wind and it does not like being trod on.
On the plus side, any off cuts will do for the perimeter insulation.

We use both foam board method and polystyrene although we do prefer foam board.

 

[^woody^]

But you can't buy 130mm of polystyrene, so the OP needs to buy 150mm thick board

80 +50 or 70 +60 or 100+ 30 ?????????????

Standard stock sizes of EPS-70 are 25, 50, 75, and 100mm.

If you are very, very lucky then you might find a local merchant that stocks all these. But for the other sizes, then you may have to special order, and then probably in pallet sizes. Who wants to be special ordering 2 or 3 sheets of 30mm board for an extension - the delivery cost would be more than the board cost

So back to the real world, and building practically and economically ..... and using 150mm of polystrene instead of 80mm of celotex or whatever

 

[hotrod]

So back to the real world, and building practically and economically ..... and using 150mm of polystrene instead of 80mm of celotex or whatever

It's called buildability woods .

 

[Raize]

1) Polystyrene doesn't have a U Value of 0.4. It has a thermal conductivity or lambda value of 0.038 W/mK

2) Celotex GA4000 or Kingspan TF70 has a thermal conductivity of 0.022 W/mK. Roughly 75% improved.

3) Polystyrene EPS70 SDN grade has a compressive strength, or kPa of 70

4) Celotex or Kingspan both have a compressive strength or kPa of 120

5) The thickness of insulation required depends wholly on the size of the floor in question, the length of the exposed perimeter and the U Value you are trying to achieve. There is no "rule of thumb" or "I always use this thickness".

HTH

 

[theoldun]

Raize, there goes a man who knows what he is talking about.

Not wishing to contradict you, but note you have not mentioned XPS which from memory has a lambda of 0.29W/mK. Do not know the Pa. Possibly you do? Would be interested to know.
oldun

 

[mointainwalker]

@ Raize

Polystyrene doesn't have a U Value of 0.4.

Who said it did ?

 

[Raize]

100 mm of expanded polystyrene has a U value of 0.4

You did.

Raize, there goes a man who knows what he is talking about.

Not wishing to contradict you, but note you have not mentioned XPS which from memory has a lambda of 0.29W/mK. Do not know the Pa. Possibly you do? Would be interested to know.
oldun

XPS does have a better thermal conductivity (0.036 - 0.033 (depending on manufacture and thickness) but it is generally harder to obtain. XPS typically has a kPa of 200, but for domestic applications that is overkill.

The price per m2 of XPS is also pretty close to PIR.

XPS used to have a lambda of 0.029, but it has been changed relatively recently. I have literature dating to 2008 with it at 0.029, but it looks like late in 2011 it's changed to 0.033 - 0.036.