25 cm of polystyrene for facade insulation – exaggeration or real need?
When we say that for quality facade insulation, at least 20-25 cm of polystyrene is required, it’s not a marketing move or exaggeration. It’s a calculation based on building standards.
According to the updated DBN V.2.6-31:2021, for the first temperature zone of Ukraine, the minimum thermal resistance (R) of walls must be at least 4 m²·K/W.
How much insulation is needed according to calculations?
We take EPS 70 polystyrene (λ = 0.039 W/(m·K)) and calculate:
Insulation thickness = R × λ = 4 × 0.039 = 0.156 m. The minimum permissible thickness is 16 cm.
But! These are ideal laboratory conditions, which do not exist in real construction. Due to cold bridges, losses through seams, and other operational factors, the effectiveness of insulation can decrease by 10-20%. To compensate for these factors and truly achieve the required level of thermal retention, the optimal insulation thickness should be 20-25 cm.
What about Europe?
In EU countries, insulation requirements are constantly increasing. For example, in neighboring Poland, the minimum thermal resistance (R) of walls is already 5 m²·K/W, which means the need for insulation with polystyrene thickness of 20 cm or more. In Germany, wall insulation with 30 cm of polystyrene is common practice, even though the climate there is much milder than ours.
What will happen if you save?
If you choose a thinner layer of insulation, your house will not achieve the required level of thermal efficiency. Heat losses will remain high, and heating costs will be significant.
What will correct insulation give?
With proper insulation, you not only get comfort and warmth in your home but also a reduction in energy resource costs in the long term.
Therefore, do not doubt—consider not only the minimum acceptable standards but also the real operating conditions and European experience!
