Insulating your loft is incredibly important. Insulation keeps your loft cool in the summer and warm in the winter, and above all it can save you a fortune on your heating bills. Without insulation, as much as 50% of your heating could disappear right from above you.
Leaking heat means leaking money. If every UK household fitted it to the recommended thickness it would save enough energy to heat 750,000 homes each year. So loft insulation is absolutely a worthwhile investment.
What thickness of insulation do I need for a loft conversion?
Building regulations stipulate that a roof’s u-value must be 0.18W/m² or less. This is achieved with either 270mm of wool or fibre insulation, 175mm of rigid board insulation or 125mm of insulating spray foams.
In older houses there’s often as little as 25mm of insulation, and existing insulation can sometimes end up compressed by storage boards laid over the top and this makes it far less effective. So even if you’re not converting your loft, improving roof insulation might be worth considering.
You’re able to easily top up your existing insulation by using loft roll (blanket insulation). But if you want to be able to walk around your loft or its storage boxes, you’ll need to lay down polystyrene board insulation on top of the joists and secure chipboard loft boards on top of this.
We’ll go into more detail below, but to meet Buildings Regulations for thermal performance requirements, it’s recommended that you aim for a u-value of 0.11W/m².