What does additional insulation cost?
Walls: 600-1,400 SEK/m2 (internal) or 800-1,800 SEK/m2 (external). Attic/roof: 200-500 SEK/m2 for accessible attic insulation. ROT-eligible. Payback in energy savings of 7-15 years.
Sources: Energimyndigheten
Here are 10 common questions and answers in the category insulation for the Swedish construction industry. Every answer is anchored in primary law (PBL, BBR, KTjL, AFS, ABS 18, AB 04) and authoritative guidance. The data is open and free to use with attribution.
Walls: 600-1,400 SEK/m2 (internal) or 800-1,800 SEK/m2 (external). Attic/roof: 200-500 SEK/m2 for accessible attic insulation. ROT-eligible. Payback in energy savings of 7-15 years.
Sources: Energimyndigheten
Mineral wool (Isover, Paroc): cheap, fire-safe, the most common. Cellular plastic (EPS/XPS): light, moisture-resistant, an environmental concern. Hemp fibre, cellulose: natural, somewhat more expensive. The choice depends on location and budget.
Sources: Materialjämförelser
BBR 2026 requirements: roof U-value max 0.13 (350 mm mineral wool), exterior wall max 0.18 (240 mm), basement max 0.20. Passive house: even better. Zaragoza AB calculates per project.
Sources: BBR 9
Yes, additional insulation of an existing building qualifies for ROT. New construction: no. Materials are not ROT-eligible.
Sources: Inkomstskattelagen 67 kap.
Warm air rises, so 25-40% of heat loss goes through the attic ceiling. Adding mineral wool (a straightforward, accessible measure) is one of the best energy investments. Payback often 5-10 years.
Sources: Energimyndigheten
Yes, from outside (best but expensive due to excavation) or inside (cheaper but risk of moisture problems if done incorrectly). A moisture barrier is critical. Zaragoza AB does both.
Sources: Svensk Fuktskydd
Thermal transmittance coefficient, W/m2K. Lower is better insulation. BBR 9 sets limit values for different building parts. Passive houses have extremely low U-values (0.08-0.10).
Sources: BBR 9
Parts of the construction with higher thermal conductivity (e.g. concrete beams through insulation). They cause energy loss and condensation problems. Should be designed out in modern buildings. Zaragoza AB considers thermal bridges in all projects.
Sources: BBR 9
Yes, known as a "warm roof" - insulation on top of the rafters. Works well when replacing the roof. Alternative: "cold roof" with insulation above the ceiling. Both are acceptable under BBR.
Sources: BBR 9
A diffusion-open wind barrier outside (e.g. Isola Tyvek). Vapour barrier foil (PE film) on the inside of the insulation for traditional construction. Intelligent vapour retarder for diffusion-open construction.
Sources: Materialtillverkare