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Kingspan Insulation equivalents


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Hi folks i'm doing a self build extension my drawings ask for kingspan kooltherm k7 to be placed between the ceiling ties and the same above to achieve a maximum u value of 0.11w/m2k. The floor asks 175mm kingspan kooltherm K3 maximum u value 0.15w/m2k.

Is there any insulation experts on here who could suggest an alternative cheaper product to kingspan to achieve the u values thank you.   

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For some reason architects love to specify Kingspan K7 which has conductivity of 0.2W/mK versus Celotex GA3/4000 or Kingspan TP10 at 0.22/0.23.

 

The Celotex is between 2/3 and 1/2 the price of the K7, the U-value would be around 0.13 instead of 0.11 for the roof.

 

You would get a similar saving and 10% worse U-value using Celotex GA3/4000 in the floor. There are other makes as mentioned above, generally any PIR insulation with a conductivity of around 0.22 will do. The Kingspan is considerably more expensive phenolic insulation which I would only pay for if it was absolutely necessary that it was a little thinner.

 

You can also sometimes buy seconds of these which are cheaper again.

 

The other thing I would note is that you cannot get 175mm insulation, you will need to buy 100mm and 75mm. This adds a bit to the cost and labour, although I am guessing that you are doing it yourself.

 

 

Edited by AliG
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45 minutes ago, AliG said:

The other thing I would note is that you cannot get 175mm insulation, you will need to buy 100mm and 75mm. This adds a bit to the cost and labour, although I am guessing that you are doing it yourself.

 

 

When discussing this option with a screeding/UFH pro the other day he said "thin down first, thickest layer on top".

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5 minutes ago, Onoff said:

I've 175mm of "insulation" under my bathroom floor. 25mm eps then 150mm of pir above that. 

 

2 minutes ago, epsilonGreedy said:

 

When discussing this option with a screeding/UFH pro the other day he said "thin down first, thickest layer on top".

 

25mm EPS is quicker and easier to use as blinding than sand and it adds a thermal layer too. Also stops any DPM getting punctured. 

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14 minutes ago, PeterW said:

 

 

25mm EPS is quicker and easier to use as blinding than sand and it adds a thermal layer too. Also stops any DPM getting punctured. 

 

I did a sand blind first dead level. Found it very Zen!

 

SAM_1087

 

SAM_1090

 

Then the 25mm eps:

 

SAM_1092

 

Then the dpc:

 

SAM_1633

 

Then the pir:

 

SAM_1824

 

Think I put thick down first! Putting the 50 down first followed by the 100 would have been better I think.

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4 minutes ago, Ed Davies said:

Seems to me that an advantage of two layers is that you can stagger the joints reducing any air paths if the stuff shrinks or moves a bit.

 

Yep. I foil taped the joints on both layers.

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Thanks for all the replies folks I should have said in my original post Im using TJI floor joists that I picked up as leftovers from a job. Regarding U values would building control let me away with 0.13 instead of 0.11 what are folks experience of this? 

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These are the figures from the building regs. Assuming that the house you are extending has a decent level of insulation the limit for a flat roof is 0.18. This can be varied if other elements are better than the limits.

 

 

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"For some reason architects love to specify Kingspan K7 which has conductivity of 0.2W/mK versus Celotex GA3/4000 or Kingspan TP10 at 0.22/0.23." - I think for some it has just become the generic term like Hoover or (can't think of another one just now, but you know what I mean)  

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  • 3 years later...
On 01/10/2018 at 23:22, epsilonGreedy said:

 

When discussing this option with a screeding/UFH pro the other day he said "thin down first, thickest layer on top".

 

The K103 spec sheet states "Where multiple layers of insulation of different thicknesses are used, the thickest layer should be installed as the outermost layer in the construction."

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