PANELO Insights / Insulation

PUR Insulation vs Mineral Wool – What Is the Difference?

Both PUR insulation and mineral wool can provide effective thermal insulation. The important differences are in thermal performance, moisture behaviour, installation and how the insulation becomes part of the building structure.

Choosing insulation is not only about comparing thermal conductivity values. How the insulation is installed, protected from weather and integrated into the building envelope can be equally important.

Mineral wool is widely used in timber construction and can provide excellent performance when correctly designed, installed and protected from moisture.

Closed-cell PUR insulation takes a different approach. In the PANELO system, the insulation is not installed on the construction site. It is injected into the panel during factory production, where it expands and bonds with the timber frame and structural facings.

This difference changes not only the thermal properties of the element, but also the way the building is manufactured and assembled.

Thermal performance: achieving more with less thickness

One of the main differences between closed-cell PUR and mineral wool is thermal conductivity, commonly expressed as lambda (λ).

The closed-cell PUR used in PANELO panels has a thermal conductivity of approximately 0.024 W/mK.

Typical mineral wool products used in building construction generally have higher thermal conductivity. The exact value depends on the specific product, density and application.

Because lower thermal conductivity means greater thermal resistance for the same thickness, PUR can achieve a high level of insulation performance with a comparatively thinner insulation layer.

Moisture during construction matters

Site-installed mineral wool

Mineral wool and the surrounding timber structure must be appropriately protected from rain and excessive moisture during construction. If components become wet, the structure should be allowed to dry sufficiently before it is closed.

Factory-installed PUR

In a PANELO panel, the PUR insulation is installed during production inside a controlled factory environment rather than being fitted into the structure on site.

Closed before delivery

The insulation is already incorporated between the panel facings before the finished structural element is transported to the construction site.

The biggest difference may be where the insulation is installed

With traditional timber-frame construction, insulation installation is typically one of several separate operations carried out on the building site or during element production.

PANELO integrates this process into panel manufacturing. Liquid PUR is introduced into the closed panel cavity, where it expands to fill the available space and bonds to the timber frame and panel facings.

This removes a separate on-site insulation installation stage and reduces dependence on manual cutting and fitting of insulation between individual structural members.

Installation gaps and thermal continuity

Insulation performs best when it forms a continuous layer without unintended gaps.

With insulation materials that are cut and fitted between structural members, installation quality is therefore important. Poor cutting, compression or incomplete fitting can create local areas where thermal performance is reduced.

Some flexible or loose insulation products can also be susceptible to movement or settlement if the material is unsuitable for the application or is incorrectly installed. This is not an inherent problem with all mineral wool systems, but correct product selection and installation are important.

PANELO takes a different approach. The PUR expands during panel production and fills the cavity around the integrated timber structure. Once cured, it forms a rigid insulation layer inside the panel.

Insulation and airtightness are not the same thing

A well-insulated building must also control unintended air leakage. These are related, but separate aspects of building-envelope performance.

Mineral wool itself is generally not used as the primary airtight layer. Timber-frame construction therefore relies on correctly designed membranes, boards, tapes and connection details to create the required airtight envelope.

PANELO combines rigid closed-cell insulation with structural facings in a factory-made element. Airtightness still depends on the complete building design and particularly on correctly detailed panel joints, openings and connections.

Using large prefabricated elements can reduce the number of site-made connections compared with constructing the same envelope from many smaller components, simplifying the amount of detailing that must be completed on site.

In PANELO, PUR is more than a layer of insulation

PANELO panels contain an integrated load-bearing timber frame. During production, closed-cell PUR is injected between the panel facings, where it expands around the timber structure and bonds to the surrounding components.

The timber frame, rigid insulation and structural facings therefore work together as a factory-made composite panel.

This is an important distinction from a conventional timber-frame wall where insulation is primarily installed between separately constructed framing members.

PUR insulation vs mineral wool at a glance

Characteristic PANELO closed-cell PUR Mineral wool
Installation Injected into the panel during factory production. Typically supplied as batts, rolls or boards and fitted into the construction.
Thermal conductivity Approximately 0.024 W/mK for the PUR used by PANELO. Depends on the specific mineral wool product and application.
Required thickness Lower thermal conductivity allows high thermal resistance with comparatively less insulation thickness. Typically requires a greater thickness to achieve the same insulation resistance as lower-lambda PUR.
Fitting around structure Expands inside the panel cavity around the integrated timber frame. Must be correctly cut or fitted around structural members and details.
Rigidity Forms a rigid insulation core after curing. Depends on product type; many timber-frame products are flexible or semi-rigid.
Moisture during construction Insulation is incorporated into the panel during controlled factory production. Requires appropriate protection from excessive moisture during storage and construction.
Site cutting No separate on-site cutting of the panel insulation. May require cutting and fitting during installation, depending on the construction method.
Integration with panel Bonds with the timber frame and facings during PANELO production. Generally functions as insulation installed within or around the structural system.

What about long-term performance?

Both PUR and mineral wool can provide long service lives when the complete building envelope is correctly designed and constructed.

Long-term insulation performance is affected not only by the insulation material itself, but also by moisture control, installation quality, air leakage, structural details and the overall design of the building envelope.

This is why PANELO focuses on integrating as many critical operations as possible into controlled factory production rather than relying on multiple separate operations on the construction site.

Which insulation system is better?

There is no single insulation material that is best for every building. Mineral wool offers advantages including non-combustibility and is widely used successfully in timber construction.

Closed-cell PUR offers particularly strong thermal performance for its thickness and can be integrated directly into a factory-manufactured panel.

For PANELO, the key advantage is therefore not simply the insulation material in isolation. It is the combination of the load-bearing timber frame, closed-cell PUR, structural facings and project-specific factory production in one ready-to-install building element.

Continue exploring

Prefabricated Timber Construction → Learn how factory-made timber construction reduces work on site.
SIP Panels vs PANELO → Compare conventional SIP construction with the PANELO system.
Wall Panels → Explore prefabricated load-bearing PANELO wall panels.
Roof Panels → Explore insulated structural PANELO roof panels.

Looking for a high-performance prefabricated timber system?

Send us your architectural drawings and we can evaluate how PANELO wall, floor and roof panels could be used for your project.

Discuss Your Project