Comparing the main characteristics of internal wall cassettes (IWC) with mineral wool and PIR sandwich panels.
Sometimes, in order to reduce the cost of a project, commercial real estate customers consider several options for wall construction, including those with internal wall cassettes or sandwich panels. At the same time, customers mistakenly believe that the IWC option will be the cheapest.
The internal wall cassette is a profiled steel structure made of galvanized sheet used as a load-bearing wall structure. Unlike prefabricated sandwich panels, IWC is not a ready-made wall structure, but requires further insulation, sealing and installation of external cladding. The advantages of internal wall cassettes include the low price of the product and the possibility to choose different cladding materials for the facade. And the disadvantages are high labor intensity of work, low energy efficiency and durability.
If we compare the total cost of a wall structure including installation based on sandwich panels and IWC with insulation and cladding, then the most attractive solution will be the sandwich panels with polyisocyanurate foam core (see table below). At the same time, mineral wool sandwich panel costs 14% more than structure with IWC, but it’s 15% more energy efficient. The higher energy-saving properties of the sandwich panels allows the building owner to recoup the price difference of wall structures already in the first 2-3 years of operation and save significantly in the future.
<tr”>Total cost of construction including installation, €/m252.359,748.6
IWC 100 mm
Sandwich panels Ruukki nSPB 100W
Sandwich panels Ruukki SP2B 80X-PIR
|Energy efficiency||Low||High||Very high|
|Thermal resistance of the structure, taking into account cold bridges R0 at 25 °С, m2*K/W||2.15||2.27||3.79|
|Heat transfer coefficient U at 25 °C, W/(m2*K)||0.47||0.44||0.26|
|The presence of cold bridges||Yes, linear every||No||No|
|Perception of operational loads from hinged structures||Badly||Great||Fine|
|Appearance||Most often determined by the type of trapezoidal sheet||Flat surface with profiling options||Flat surface with profiling options|
|Structure tightness||Low, sealant is installed on site||High, sealant is installed at the factory||High, sealant is installed at the factory|
|Area required for storage of 100 m2 of facade, m2||35||12||9|
|Installation speed of 100 m2 facade by a team of 3-4 specialists, hours||28||7||7|
|All-weather installation||Impossible||Possible with restrictions||Possible|
|Structure weight, kg/m2||25||20.6||11.2|
|Installation without crane||Possible with restrictions||Impossible||Possible|
|Fire resistance||EI 30 with restrictions||EI 90||EI 15|
|Corrosion resistance||Low, many centers of corrosion where dust accumulates||High, no places for dust accumulation||High, no places for dust accumulation|
|The need for protection in an aggressive environment||Both sides of IWC and cladding||The outer side of the cladding||The outer side of the cladding|
|Up to 20 limited by the service life of the applied sealants and thermal insulation tape||Over 50||Over 50|
|Up to 10
for some items
|Up to 30
for the structure
|Up to 30
for the structure
|Operating costs for the building (heating, air conditioning, repairs, etc.)||High||Medium||Low|
|Materials cost*, €/m2||40.3||48.3||39.0|
|Installation cost*, €/m2||12.0||11.4||9.6|
|Total construction cost with installation*, €/m2||52,3||59,7||48,6|
* Prices are valid as of the date of writing the article
Given the significant advantages of sandwich panels over IWC, it can be concluded that it is advisable to use internal wall cassettes for temporary facilities or in the construction of buildings that have lower requirements for energy efficiency and durability. With increased requirements for fire resistance, it is recommended to use sandwich panels with mineral wool, and to achieve highest energy efficiency, it is recommended to use sandwich panels with PIR core.