Liz wrote:

The items are in the catalogue and in the insulation pdf, but these
two don't have the R value quoted.

Do they quote a k value (thermal conductivity in W/mK)? If so then R is
just the thickness (in metres) divided by k.

If we're talking about expanded polystyrene then k will be about 0.034
W/mK so, for the 50 mm material, R will be about 0.05/0.034 i.e. about
1.4 to 1.5 m^2K/W - and so on. The high density material will probably
have a higher k value - 0.04 W/mK perhaps.

--
Andy