Before looking for iso board r values, consider the full range of r values that you can achieve on your property with EPS (expanded polystyrene) panels. These are installed prior to the house siding for a wider range of combinations between siding choice and r values. With a wide range of thicknesses and densities available from Universal Foam Products, you can build up the insulation specifications you need in different areas or properties. EPS (expanded polystyrene) is a lightweight, easy to use material with pre-cut panels shipped to site from more than 100 locations nationwide.