Attic floor or roof slope? The choice in one question

The whole choice hinges on one question: do you use the attic, or not? Heat rises, so the roof is the largest cold surface at the top of the house. But where you stop that heat depends on how you live. If you use the attic only for storage, you don't need to keep the space above warm — you stop the heat a floor lower instead.

In that case insulating the attic floor (€ 1,000 to € 2,500) is the logical choice: insulation boards or rolls lie loose on the attic floor, the lived-in floor below stays warm and the attic itself becomes the cold buffer space. It is the fastest and cheapest measure, often done in a day and without a finish — the insulation doesn't need to look pretty, it lies out of sight.

If you live or work in the attic, or plan to, the heat has to stay a floor higher and you insulate the roof slope itself. Insulating the sloped roof from the inside (€ 2,500 to € 8,000, roughly € 50 to € 100 per m²) means insulation material against every sloping roof surface, neatly finished with boards or plasterboard. More expensive and more work, but you keep the attic as a full room — comfortable in winter and cooler in summer.

If you are still unsure, or a flat roof or a dormer is also in play, it is worth having it assessed. An insulation survey with thermal scan (€ 95 to € 250) shows where your home loses the most heat and in what order insulating pays off. One thing falls outside all of this: insulating the roof on the OUTSIDE during a re-roof is a roofer's job. The bands per measure are in the price index.