Answers

What is the best insulation for a house in Extremadura?

Expanded cork on the facade, a wood-fibre board on the roof, and blown cellulose if you are retrofitting without opening the walls. In Extremadura the problem is summer, not winter: 265 of its 388 municipalities sit in climate zone C4 of the Spanish Building Code, and that 4 is the highest summer severity on the scale. A light insulation stops the cold as well as a heavy one with the same conductivity, but against July heat what counts is how much mass stands between the sun and you. We calculated it: on a roof insulated from the outside, 14 centimetres of wood fibre delay the heat wave by eight and a half hours; the same roof with mineral wool, three.

Reviewed on September 2026