Fibre Reinforced Facade Encyclopedia: Design and detailing
Design life is the period for which a building element is intended to perform its function without unforeseen replacement, assuming it is maintained as specified. It is a design decision made at the start of a project, not a measurement and not a guarantee. For an external wall the conventional figure is 50 years, matching the design working life of a normal building structure, while the components inside that wall, sealants, gaskets, coatings and fixings, carry much shorter figures and are expected to be replaced within it.
Design life is what the designer intends. Service life is what the building actually gets. Warranty is the much shorter period over which somebody will pay if it goes wrong.
At a glance
| Property | Typical value | Note |
|---|---|---|
| Framework | ISO 15686 Buildings and constructed assets: service life planning | Parts 1 to 11 cover principles, methods and data |
| Building structure | 50 years design working life, typical | AS/NZS 1170.0 Table for a normal structure |
| Facade cladding | 50 years typical; 25 years on some projects | Set by the brief, not by code |
| Sealants | 10 to 25 years | Replaceable within the facade design life |
| Coatings | 15 to 25 years to first full recoat | PVDF at the long end; recoat interval is a maintenance item |
| Fixings and substructure | Full design life | Stainless steel or equivalent, not replaceable without removing panels |
| GFRC panels | 40 to 50 years | Long-term aged strength, not 28-day strength, is the design basis |
| Warranty period | Commonly 10 to 15 years on the system | Contractual, and far shorter than the design life |
Design life, service life and warranty
The three get used interchangeably and mean different things. Design life is a requirement set in the brief: the client states how long the facade is to last and the designer selects materials, details and a maintenance regime capable of delivering it. Service life is the outcome: how long the element actually performs before it has to be replaced, which depends on the environment it ends up in and whether anybody maintained it. Warranty is a commercial position: the period over which the supplier or contractor accepts liability, usually a fraction of the design life, and normally void if the maintenance regime was not followed.
A 50 year design life with a 10 year warranty is not a contradiction. It means the system is designed to last 50 years and somebody is prepared to stand behind the first 10. What it does mean is that the evidence for the other 40 has to come from somewhere other than the warranty document, which is where ISO 15686 and aged property data come in. The durability page covers the material degradation mechanisms themselves; this page is about how the period is set and demonstrated.
What ISO 15686 asks for
ISO 15686 is the international framework for service life planning. Its central tool is the factor method, which starts with a reference service life for a component, established from testing or from documented experience in a known environment, and then adjusts it by a series of factors for the things that make one installation different from another: the inherent quality of the component, the design level, the standard of workmanship, the indoor environment, the outdoor environment, the in-use conditions, and the maintenance level. Each factor is a multiplier above or below 1.0, and the result is an estimated service life for the component in this building, on this site.
The method is deliberately transparent rather than precise. Its value is that it forces the assumptions into the open: a panel with a 50 year reference service life inland does not have a 50 year service life in a C4 coastal industrial zone with no cleaning regime.
The NCC position
The National Construction Code (check the edition adopted in your jurisdiction) does not set a general durability or design life requirement for cladding in the way it sets fire and structural requirements. The structural provisions require resistance to actions determined under the AS/NZS 1170 series, and AS/NZS 1170.0 adopts a design working life, 50 years for a normal structure, as the basis for the return periods used to derive them. Material durability enters through the referenced standards and through ABCB guidance, which is advisory rather than mandatory.
Design life on an Australian facade is therefore a contractual matter, set in the brief and the specification. A specification that says nothing about design life has specified nothing about design life.
What a 50 year design life actually obliges a manufacturer to demonstrate
- Aged property data, not fresh data. For glass fibre reinforced concrete (GRC, GFRC) that means designing on long-term aged modulus of rupture and limit of proportionality values rather than 28-day values
- Evidence of the degradation mechanism being controlled: alkali resistant glass fibre with a stated zirconia content for GRC, resin system and gel coat performance under UV for fibre reinforced polymer, and a coating system with a stated recoat interval
- Corrosion design of everything that cannot be replaced: anchors, fixings, brackets and rails specified to a grade appropriate to the exposure category for the full period, not the same grade everywhere
- An exposure assessment: the atmospheric corrosivity category of the actual site, distance from surf or industrial sources, and the cleaning frequency assumed
- A written maintenance regime, with inspection intervals, cleaning method and the replacement points for sealants, gaskets and coatings, and an access strategy that makes those replacements possible
- Consistency between the design life stated and the manufacturing controls behind it, which is where factory production control and batch records earn their place
If a supplier states 50 years and can produce none of the above, the number is an opinion. The specification should ask for the evidence rather than the claim.
Standards and references
- ISO 15686 parts 1 to 11, Buildings and constructed assets: service life planning, including the factor method
- AS/NZS 1170.0 Structural design actions: general principles, design working life
- GRCA Specification for the Manufacture, Curing and Testing of GRC Products, and its guidance on aged design values
- BS EN 1169 factory production control and BS EN 1170 test methods for GRC
- NCC 2022 Volume One structural provisions and ABCB Durability in Buildings guidance (check the edition adopted in your jurisdiction)
Related terms
Questions specifiers ask
What is the difference between design life and service life?
Design life is the period the element is intended to last, set in the brief. Service life is how long it actually lasts in the building. ISO 15686 provides a structured method for estimating one from the other.
Is a 50 year design life required by the NCC?
No. The NCC does not set a general design life for cladding. AS/NZS 1170.0 uses a 50 year design working life to derive structural actions for a normal building, and 50 years is the common contractual figure for a facade, but it has to be specified.
Does design life mean maintenance free?
No. Design life assumes the specified maintenance regime is carried out. Sealants, gaskets and coatings are consumable items expected to be replaced one or more times within the facade design life.
How is a design life demonstrated for a GFRC panel?
Through aged strength data rather than 28-day data, alkali resistant fibre with a stated zirconia content, corrosion resistant anchors, an exposure assessment for the site, batch test records, and a written maintenance regime.
Specifying a 50 year facade? ShapeShift supplies aged design values, batch test records and anchor specifications sized for the exposure category of the site. Request durability data
Reviewed by Richard Halvorsen, General Manager, ShapeShift Technologies. Last updated September 2026.