The advantages are as follows: 
with a thermal conductivity of 0.020-0.023 W/mK rigid phenolic insulation is the most thermally efficient insulation product commonly available
utilises the thinnest possible insulation board to achieve required U-values
achieves a Class O fire rating to the Building Regulations / low risk
 
 
 
Available in: 2400 x 1200mm, 25mm to 150mm thicknesses. Others available on request 

Melbros stock a range of top manufacturers for rigid phenolic PIR floor, wall & pitched roof insulation including Quinn Therm, Kingspan Kooltherm, Celotex FR4000 & Ecotherm 

The PIR foam core, aluminium foil faced boards can achieve required thermal standards without radical changes to construction methods and more importantly without risking a subsequent deterioration of the structure owing to the effects of roof-space condensation.