Why insulation pays off more than ever in 2026
Energy prices in recent years have taken a completely different direction than owners of older family houses got used to during the 1990s and early 2000s. Facade insulation, which still ten years ago returned the investment in about 12–15 years, today returns thanks to higher gas and electricity prices often already in 6–9 years. Added to this are state grants (Nová zelená úsporám), which cover a significant portion of the investment.
In this article we focus mainly on the practical side — how insulation works, how individual materials differ, what to watch when choosing a contractor and how much it costs. If you are considering insulation for your house in Prague or surroundings, you will find answers to the most common questions here.
Polystyrene versus mineral wool — what to choose
The two most commonly used materials for an external thermal insulation system (ETICS) are expanded polystyrene (EPS) and mineral wool. From the thermal-insulation perspective, they are comparable today (lambda around 0.031–0.036 W/m·K), but they differ in other parameters.
Polystyrene is cheaper (about 15–25 %), lighter to handle and easier to execute. However, it does not tolerate long-term temperatures above 80 °C and has worse acoustic properties — if you live near a noisier street, it shows. Mineral wool is on the contrary practically non-flammable (fire resistance is much better with it), dampens noise and "breathes" better, but is more expensive and demands more in execution.
In family houses up to two storeys in quieter locations, polystyrene is most often chosen. For multi-storey buildings, buildings near busy traffic or where fire resistance is critical, mineral wool makes sense.
Insulation thickness — do not save where it does not pay
In 2026 the standard insulation thickness for a family house is already 160–200 mm. Thinner insulation (100–120 mm) used 15 years ago no longer makes economic sense — the price difference between 120 and 180 mm is relatively small (about 250–400 CZK/m²), while the difference in energy savings is significant.
If you are insulating as part of the Nová zelená úsporám grant programme, the rules set minimum thermal parameters that you typically achieve with thickness of 180 mm and above. Our tip: if you are already considering insulation, go directly for 200 mm and the investment will return faster.
Family house insulation price
The price for delivery of a complete contact thermal insulation system (ETICS) on a family house in Prague and surroundings in 2026 ranges from 1,600 to 2,400 CZK/m² of facade. The specific price depends on insulation type, thickness, final plaster structure and facade complexity.
For a model family house 8 × 12 m with three storeys we have about 250 m² of facade area. Polystyrene insulation 180 mm with silicone-silicate type plaster costs in such a case about 450,000–520,000 CZK including scaffolding, metalwork and coordination. Mineral wool raises the price by 50,000–80,000 CZK. After deducting the grant from Nová zelená úsporám, the client often actually pays 280,000–350,000 CZK of own funds.
What all belongs to insulation — often forgotten items
A price offer for insulation should not miss: scaffolding (50,000–90,000 CZK for a standard family house), metalwork (window sill flashing, roof overhang extensions — 30,000–60,000 CZK), all work around windows and sills, replacement or extension of rainwater downpipes, and work around the plinth (transition to XPS insulation, plinth, waterproofing).
In some offers the client does not see items for metalwork, but ends up paying for it anyway — that is why it pays to compare itemised offers and not flat-rate prices. At ERAD stav we send the offer itemised so that none of the above items remains outside the budget.
Construction progress — what to expect
Insulation of a medium-sized family house in Prague usually takes 5–8 weeks, depending on weather. It starts with substrate preparation (knocking off loose plaster, washing), scaffolding installation, mounting the starter profile, gluing insulation boards, anchoring, reinforcing layer with mesh and final plaster.
During construction the house is accessible and habitable, but you cannot open windows on the facade during working days because they are covered by scaffolding and foil. After completion we give the plaster sufficient time to cure before the first season (ideally three months).
Nová zelená úsporám grant
Most of our clients combine insulation with a grant from the Nová zelená úsporám programme. We help with preparing documents (energy assessment, project documentation, invoices) and coordinate delivery with the programme conditions. The client submits the administration themselves (or via a specialised company), but the construction contractor is a key partner in it.
If you are considering insulating your family house, get in touch with us. We will arrange the survey, propose the build-up, itemised budget and coordinate with the grant programme. We will happily calculate when the investment will return in your specific situation.