Roof insulation is really a prudently wise investment. A house loses 25% of its heat through a poorly insulated roof as heat rises. Roof insulation grants and the high cost of energy mean that you can quickly recover your investment.
In the UK, most homes have what’s known as a pitched rooftop. A pitched rooftop comprises two inclined sides that take off downwards, away from the focal edge of the rooftop. To class a rooftop as a pitched rooftop, a few guidelines express that the point of the incline needs to surpass 10 degrees or comprise multiple sides over the focal edge.
Source: https://www.homeinsulationcontractors.co.uk/roof-insulation-cost-uk-2022-price-comparison-per-m2/