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Steel house insulation raises one question more often than any other: does a steel house feel cold? No — a light steel house that is insulated with the right layers does not feel cold; with a properly built-up wall, it often heats with less energy than a reinforced concrete building. What decides whether a house feels warm or cold is not the material of the structural frame, but how the insulation layers in the wall, roof and floor are put together. In this article we look at how thermal and acoustic insulation is achieved in light steel structures, how thermal bridging is prevented, and what the updated TS 825 standard requires.
Is It True That "Steel Houses Feel Cold"?
This idea comes from intuition: metal feels cold to the touch, and steel is a metal. It is true that steel conducts heat well. What gets overlooked, though, is that what separates the interior from the outside is not the structural skeleton, but the wall as a whole. In a light steel structure, the galvanized profiles form only the skeleton of the wall; between the inner and outer surfaces sits a sequence of layers — insulation fill, boards and cladding. The living space is in contact with these layers, not with the steel.
It is also worth being clear about this: no uninsulated structure feels warm. An uninsulated reinforced concrete wall loses heat to the outside just as quickly in winter. So the real question is not "does steel or concrete keep you warmer", but "how is the wall build-up designed". In light steel, the regular cavities between the profiles make the wall inherently suited to holding insulation material within the section. This layered logic makes insulation a built-in part of the system from the start, rather than something added on afterwards.
If you would like to understand how the system works overall, take a look at our article on light steel structures; here we focus on the insulation side.
How the Wall Layer System Is Built Up
Light steel thermal insulation is not achieved with a single thick material, but through layers working together, each with its own role. From the outside in, a typical wall build-up follows this logic:
| Layer (outside to inside) | Function |
|---|---|
| Exterior façade cladding | The first barrier against rain, wind and impact |
| Continuous exterior insulation board | Covers the profiles without a break, cutting off the thermal bridge |
| Structural sheathing board (OSB or cement-based) | Gives the system rigidity and provides a base for cladding |
| Insulation fill between profiles | The main thermal and acoustic insulation volume within the section |
| Vapour control membrane | Prevents indoor moisture from condensing inside the wall |
| Interior lining (plasterboard) | Forms the interior surface and adds mass to the section |
In the industry, mineral wool and glass wool are most commonly used between the profiles, while EPS, XPS or mineral-wool-based boards are typically chosen for the outer layers. The choice of material depends on the climate zone, the façade type and fire requirements. What matters is not just which product is chosen, but that the layers are applied in the right order and without a break in continuity — details such as taping the joints in the vapour control membrane, staggering the board joints and completing the seal around window openings are what carry the section's calculated performance through to reality on site.
You can find the structural side of the wall build-up — profile dimensions, galvanized coating and the assembly system — covered in detail in our article on the technical specifications of light steel houses.
What Is Thermal Bridging, and How Is It Prevented?
A thermal bridge is the term for a point where the insulation layer is interrupted and heat escapes quickly through that spot. This matters particularly in light steel structures, because steel profiles conduct heat far more readily than timber. If insulation is placed only between the profiles, heat bypasses the fill and travels out through the profile itself. International building physics studies show that in steel walls insulated only between the profiles, the effective insulation performance can fall to roughly half of the calculated value.
For this reason, thermal bridging in light steel is solved through system design, not by increasing material thickness:
- Continuous exterior insulation: An insulation board that covers the outer face of the profiles without a break cuts off the path heat would otherwise take through the profile. This is the single most effective measure against thermal bridging.
- Thermal break strips: Low-conductivity strips placed between the profile and the outer board reduce heat flow at the point of contact.
- Detailing at critical points: Window and door edges, corner junctions and floor-to-wall transitions are where insulation continuity is most often broken; these details are drawn separately in the project.
- Airtightness: Joint and connection tapes close off uncontrolled air leaks; even the best insulation loses its effect in a section that leaks air.
A thermal bridge does not only mean a higher energy bill. Where heat escapes, the inner wall surface cools; moisture in the room air condenses on that cold surface and, over time, turns into mould, staining and damage to the finish. A correctly resolved section protects both comfort and the building's long-term condition.
Acoustic Insulation and Layer Logic
Steel house acoustic insulation shares the same layered build-up as thermal insulation, but relies on a different physical principle: mass-spring-mass. The fibrous fill between two rigid surfaces (the outer boards and the inner plasterboard) acts like a spring, damping sound energy. This is why fibrous materials such as mineral wool and glass wool are used for both thermal and acoustic insulation — a single section performs both roles at once.
Acoustic insulation deals with two distinct sound sources, each requiring its own solution:
- Airborne sound (speech, traffic, music) is addressed through the mass and fill within the wall section. Where needed, a double layer of plasterboard is applied on the interior face to add mass.
- Impact sound (footsteps, dragged furniture) is transmitted through the building elements. Floating screeds or resilient interlayers between floors, and separated studs with flexible connection profiles in walls, interrupt this transmission.
Small openings such as service penetrations, outlet boxes and duct gaps create shortcuts for sound; sealing these points carefully matters just as much as the layer build-up itself. A well-designed light steel wall also has the advantage of being easier to adapt to changing needs than a masonry wall, whose layers are difficult to alter later — the section can be varied by room function relatively easily at the design stage.
TS 825 and the Energy Performance Certificate
In Turkey, the thermal insulation of buildings is designed according to the TS 825 "Thermal Insulation Requirements for Buildings" standard. The standard was comprehensively revised in 2024 and, under a communiqué from the Turkish Ministry of Environment, Urbanisation and Climate Change, became mandatory for new buildings as of 1 April 2025. This section describes the Turkish standard specifically — other countries apply their own national energy codes. The main points of the revision are:
- The number of climate zones was increased from 4 to 6, so insulation requirements are now defined more precisely by region.
- Cooling demand was added to the calculations alongside heating; buildings are now designed with summer comfort in mind as well.
- Thermal transmittance (U) values were tightened, which in practice means more effective insulation sections.
The Energy Performance Certificate (Enerji Kimlik Belgesi, EKB) is the official document that rates a building's energy performance in Turkey. For new buildings it must be issued at the occupancy permit stage; for existing buildings, an EKB has been required for sale and rental transactions since 1 January 2020. For further detail, see the Ministry's information document (in Turkish).
Because light steel houses are permitted, permanent structures, they are fully subject to this Turkish legislation: your project is prepared together with the TS 825 calculation, and the EKB is issued once the building is complete. Since implementation details can vary by municipality, we recommend consulting the municipality your plot belongs to before starting your project.
The Effect of Insulation on Bills and Comfort
The purpose behind updating the standard is to reduce buildings' annual energy consumption without compromising on comfort. The size of the gain depends on the building's climate zone, the wall build-up used and window performance, so quoting a single percentage would be misleading. In a properly insulated light steel house, this effect works in both directions: heating load in winter and cooling load in summer both come down.
The comfort side is often felt before the bill even arrives. In a well-insulated section, the interior wall surface stays close to room temperature; the space holds its warmth for longer even after the radiator switches off, and there is no cold draught felt near window edges. Because surfaces do not cool down, the risk of condensation and mould is also removed. Lower energy consumption also means a lower carbon footprint, which reinforces the nature-friendly side of steel houses as well.
Why Correct Application Is What Determines Steel House Insulation Performance
The same materials can produce very different results; what makes the difference is design and workmanship. An untaped vapour control membrane, a skipped window detail or a break in the exterior insulation board can erode the section's calculated performance on site. At Özok Steel, we plan the insulation build-up around the project's climate zone, façade design and intended use, and settle the layer details during the design stage. You can review projects we have completed under different climate conditions on our work page.
Frequently Asked Questions
Do steel houses feel cold in winter?
No. A light steel house insulated with the right layer system does not feel cold in winter. What determines the temperature is not the frame material, but the insulation build-up within the wall section. Because the cavities between profiles are inherently suited to holding insulation fill and are supported by continuous exterior insulation, a correctly built steel house can heat with less energy than a reinforced concrete one.
How is acoustic insulation achieved in a steel house?
It relies on the mass-spring-mass principle: mineral wool or glass wool fill between two rigid surfaces damps sound energy. For airborne sound, mass and fill are increased; for impact sound, floating screeds, resilient interlayers and separated connection profiles are used. Sealing service penetrations also has a direct effect on the result.
Does thermal bridging cause problems in steel structures?
It does if left unaddressed; because steel conducts heat well, insulation placed only between the profiles is not enough on its own. The solution lies in system design: continuous exterior insulation board covering the outer face of the profiles, thermal break strips, and correctly resolved window and corner details eliminate the thermal bridge effect.
Is the Energy Performance Certificate mandatory for steel houses?
Yes. Because light steel houses count as permitted, permanent structures in Turkey, they are subject to EKB legislation. For new buildings, the certificate is issued at the occupancy permit stage; for existing buildings, it has been required for sale and rental transactions since 1 January 2020. The certificate shows the building's energy performance rating.
What insulation materials are used in a light steel house?
In the industry, mineral wool and glass wool are typically used between the profiles, and EPS, XPS or mineral-wool-based boards on the exterior face. The choice of material is decided in the project according to climate zone, façade type and fire requirements; what matters most is not the material alone but applying the layers without a break in continuity.
To plan the insulation build-up for your project together, you can get in touch with us and we can review the solutions suited to your climate zone.
This article is for general information purposes. Insulation material, thickness and layer details vary according to the project, façade design and the climate zone of the building's location; project-specific values are determined by the TS 825 calculation.
