floor insulation

[tony_m]

I need to insulate the ground floor which is a traditional victorian type suspended timber floor. The regs, Approved Document L1B Conservation of fuel and power change of use in existing Buildings, require a value of 0.22 W/m²K. Celotex and kingspan 75mm have a value of 0.022W/m2K.
TBH I don't really understand the values. Am i right in saying that the higher the w/m2k value the better the insulation performance and what PIR insulation meet the requirements for change of use sub floor insulation. I would call the BCO but its the weekend and I want to source the materials for next week.

 

[freddiemercurystwin]

The measure is the amount of heat loss through a material so the lower the figure the better.

Celotex, Kingspan, all PIR's are much the same.

Have a look at the Celotex U Value Calculator (you will have to register but its free and instant) this allows calcs to be undertaken for most scenarios.

 

[^woody^]

The insulation manufacturers will state the K-value, which is the insulation efficiency of the single material.

B/regs will mention the u-value, which is the efficiency of a combination of materials to make up a wall/floor/roof etc

Lower is better in each case

I think you may need 120mm of kingspan, but check first

 

[theoldun]

Unfortunately you are falling into a trap that a lot of other people fall into.
Briefly, insulation companies do not give a U value as they do not know the thickness of insulation, or type of construction that you will be forming, how ever they do give a Lambda value which is thermal conductivity known as a K value and expressed as W/mK..
From the K value thickness, you then calculate the resistance value known as R value and expressed as m2K/W.
Once you know your total R value, you can then calculate your U value expressed as Wm2/K. In certain cases cold bridging also has to be taken into consideration.
Take to long to explain calculations, and as we do not know your P/A ratio or area can not advise thickness of insulation required. Suggest you take Fred the Treads advice and visit celotex calculator. If still unsure then come back with area of room and P/A ratio.
Regards oldun