Thermal insulation

Thermal insulation (zateplení) means adding insulation to the building envelope: external walls, the roof, the ceiling below an unheated loft or the floor above a cellar. Facades are most often insulated with an external thermal insulation composite system (ETICS) using expanded polystyrene or mineral wool boards that are glued, anchored and covered with a reinforcing layer and render.

What insulation changes

• It reduces heat loss and heating costs and improves comfort and the class in the energy performance certificate.
• If works affect more than 25% of the total area of the building envelope, Act No. 406/2000 Coll. treats them as a major renovation: the building must meet energy performance requirements and the owner must obtain a new certificate.
• In apartment buildings, since 2024 the quality of the envelope also determines the share of the basic component when heating costs are split between flats.

What to watch out for

A tighter house needs enough ventilation. The decree on building requirements sets, for habitable rooms while occupied, an air exchange of at least 0.5 room volumes per hour or 25 m3 of outdoor air per hour per person. This can be provided by windows or by mechanical ventilation, for example heat recovery ventilation.

When buying, ask when and with what the building was insulated, how thick the insulation is and who did the work. Cracks in the facade, mould in corners and around windows, or the state of the plinth and sills indicate the quality of the work.

Frequently asked questions

Is insulation recorded in the register?

No. The construction type in the RÚIAN register describes the state at completion and does not reflect later insulation. Look for it in the energy performance certificate, the building documentation or the paperwork for any subsidy.

Is there support for insulation?

The state supports energy-saving measures mainly through the Nová zelená úsporám programme, run for the Ministry of the Environment by the State Environmental Fund. Forms of support (grants, favourable loans) and conditions change with each call, so they need to be checked before work starts.