System-s

Frame wall cross-section – See what protects your home from the cold

Anatomy of heat – what do the layers of a wall in a frame house hide?

To understand why a modern barn-type house is warm even in bitter frosts, we must look inside the structure. It is not enough to simply "stuff" insulation between the posts. The key is the order and properties of individual materials. Below we present a schematic description of what it looks like in the System-S standard, going from the outside in:

Frame house wall layers:

  • External facade – e.g., facade board, seam metal, or plaster. This is the first line of defense against rain and mechanical damage.
  • Ventilation grate (battens and counter-battens) – a key element creating a ventilation gap. Thanks to it, moisture can evaporate freely, and the wall does not degrade.
  • Wind barrier – high-vapor-permeable membrane. Protects the structure and wool from wind-washing (which drastically lowers insulation effectiveness) and water, while allowing the wall to "breathe" outwards.
  • External sheathing board – stiffens the frame structure.
  • Load-bearing structure + Thermal insulation – the heart of the wall. Certified structural timber (C24) tightly filled with insulating material.
  • Vapor barrier foil – an absolutely necessary barrier from the interior side. Its task is to stop moisture produced by household members so that it does not penetrate deep into the wool.
  • Installation grate + additional insulation – a place to run cables and pipes without violating the main vapor barrier, often filled with an additional layer of wool.
  • Internal finish – e.g., plasterboards, wooden paneling, or furniture board.

Building physics: Wind barrier vs. Vapor barrier – why are they not the same?

Many contractors confuse these terms, which leads to catastrophic errors. As experts, we must emphasize: wind barrier and vapor barrier are two different shields with opposite actions.

The wind barrier (outside) acts like a Gore-Tex jacket – it doesn't let wind and rain in, but allows sweat (technological and living moisture) to get out. If we didn't use it, the cold wind would "blow out" the heat from the wool, drastically lowering its effectiveness. Conversely, the vapor barrier (inside) is a tight dam. Wet wool loses its insulating properties – a wet sweater doesn't keep you warm. That is why we approach the tightness of connections at the foil installation stage so strictly. It is this attention to detail that makes frame technology houses so energy-efficient.

Mineral wool or PUR foam – the eternal dilemma

Analyzing the frame wall cross-section, we face the choice of insulator. The market is divided into supporters of wool (rock/glass) and polyurethane foam (PUR). What to choose? The answer depends on expectations, but physics points to certain directions.

Wool or foam? Wool is a naturally non-combustible material and, crucially, has excellent acoustic properties. In frame houses, soundproofing is extremely important, and heavy rock wool dampens sounds superbly. Additionally, it is vapor-permeable, which interacts with the diffusion-open wall structure. PUR foam (open-cell), in turn, fills hard-to-reach gaps well, eliminating thermal bridges, but its application requires a technological regime (appropriate wood humidity), and acoustic parameters can be worse than in the case of high-density wool.

In our realizations, we rely on proven solutions that guarantee not only warmth but also fire safety and acoustic comfort, which is why we most often recommend systems based on high-quality wool.

Heat transfer coefficient U – numbers don't lie

The final test of partition quality is the heat transfer coefficient U. The lower the value, the better – the less heat escapes from your home. According to current Technical Conditions (WT 2021), external walls must have a U-factor not higher than 0.20 W/(m²K).

For us, the norm is not enough. Our walls, thanks to the use of appropriate timber sections and high-class insulation materials, achieve parameters significantly better, often oscillating around U = 0.13 – 0.15 W/(m²K). This means your home is ready for the future, and heating bills are minimal. Remember that the final result is decided not only by the wall thickness but primarily by the elimination of thermal bridges at board joints and corners, which is easier to control in frame technology than in masonry.

FAQ - Frequently asked questions

The total wall thickness depends on the finish and insulation, but usually ranges from 25 to 35 cm, with the thermal insulation layer being key, which is approx. 20-25 cm in the energy-saving standard.

Properly installed wool of appropriate density (e.g., rock wool slabs) does not settle. Settlement problems concerned old technologies or execution errors using materials that were too soft.

Yes, but in the sense of technical moisture removal. Thanks to the wind barrier, technological moisture can escape to the outside, while the vapor barrier protects the inside of the wall from moisture from the house.

Our walls typically achieve a U-value in the range of 0.13 – 0.15 W/(m²K), which exceeds the current requirements of Technical Conditions 2021.

Both materials have advantages, however, due to acoustics, fire resistance, and diffusion openness, we most often recommend mineral wool in our structures.
Share