Beginner’s guide to choosing insulation

Insulation is one of the key elements to achieving a thermally efficient house, along with airtightness. But it can be difficult to know what’s best and how to get it right. How much do you need? Should it be natural or man-made? Is one a better insulator than the other? A decade or 15 years ago, insulation was insulation and we put in what the Building Regs told us to. But things have changed and the significance of insulation has increased exponentially, which can serve to increase confusion.

The different insulation materials

Insulation materials divide themselves into two groups: natural and man-made. Both have their benefits and their drawbacks.

• Man-made

Rigid foam including phenolic foam, polyurethane (PUR) and polyisocyanurate (PIR). PIR and phenolic foam have largely taken over from PUR but they all have a high closed cell content and fine cell structure (small bubbles and lots of them) and are all largely the same in terms of insulation performance.

This is familiar to everyone in its many forms and uses. At one time the default floor and wall insulation, it has now largely