If the house is built using solid wall or hollow block construction methods, cavity fill insulation is not an option and internal insulation can be used. Internal insulation (sometimes referred to as 'drylining') involves fixing insulation to the inner surfaces external walls. This usually involves fixing an insulation board to the walls and covering it with a vapour barrier layer and plasterboard. One of the main disadvantages of internal insulation is the loss of room space; this may be minimised by using high performance insulation products that are thinner. While this is often a more affordable option than installing external wall insulation, the loss of space and potential necessity to take out and re-fit fitted kitchens and appliances can result in people choosing the external insulation option.
Insulation Shop offers a wide range of high performance PIR rigid insulation from manufacturers Celotex, Xtratherm. That includes PIR boards bonded to plasterboard (Celotex PL4000) which gives user the ability to install both the insulation and plasterboard in one operation thus significantly reducing installation time.