Building EnvelopeA2P1072: Building Envelope Components: Examining Service Lives and Lifespans

Introduction

The service life of a building envelope component refers to the expected duration for which that specific part of the structure is designed to function effectively without requiring major repairs or replacement. Longevity and low maintenance are attributes often sought after in architecture but achieving them requires meticulous planning and a deep understanding of the components involved. This article aims to serve as a comprehensive guide detailing best practices and design considerations for enhancing the service life of critical building elements. The goal is to facilitate the creation of structures that are not only durable but also economically and environmentally sustainable in the long run.

As this article will discuss, service life can be notoriously difficult to predict due to the variety of factors that influence it – but that only makes it more important to be remain cognizant of these factors and plan accordingly.

Knowing the service life of various building envelope components is vital for several reasons. First, it aids in planning and construction. Engineers and architects can make informed choices about materials and designs that align with the desired lifespan of the building. Second, it significantly impacts maintenance schedules. A clear understanding of when a component is likely to fail or require upkeep allows for proactive measures, reducing emergency repairs and associated costs. Finally, understanding service life is crucial for calculating long-term costs, such as when evaluating the total cost of ownership for commercial or residential buildings.

Each building envelope component is critical in its way for the structural integrity, aesthetic appeal, and functionality of any edifice. These components are:

1. Foundations: The bedrock upon which the entire structure stands, foundations are critical for long-term stability.
2. Framing/Sub-Framing: The skeleton of the building, framing defines the shape and providing the basic structure for other components to be attached.
3. Cladding: Often considered the “skin” of a building, cladding serves both aesthetic and functional purposes, including protection from the elements.
4. Sealants: These materials act as barriers to prevent the ingress of water, air, and other environmental factors, helping maintain the interior conditions of a building.
5. Windows: Beyond letting in light and providing views, modern windows offer thermal and sound insulation, significantly impacting the building’s energy efficiency.

Each of these building envelope components has its own typical service life, influenced by factors such as material quality, environmental conditions, and maintenance practices. Read on to gain a comprehensive understanding of what you need to know to effectively plan for, maintain, and manage the long-term health of your building.

 

Building Envelope Component: Foundations

 

Foundation Type	Average Typical Life	Range	Average Minimum Life	Average Maximum Life
General Foundations	110 Years	36 to over 100 years	60 years	175 years

Adapted from “Life Expectancy of Building Components: Surveyors’ Experience of Buildings in Use; a Practical Guide,” by M. Harvey.

 

Foundations serve as the bedrock for any building structure, transferring the load of the building to the ground. They play an essential role in ensuring the stability, durability, and safety of a structure. Think of foundations as the roots of a tree, anchoring it firmly into the soil. Just as the health of a tree is dependent on its roots, the long-term viability of a building is closely tied to the quality and maintenance of its foundation.

Types of Foundations:

• Shallow foundations, also known as spread footings or open footings, are typically used when the soil near the surface has sufficient bearing capacity to support the structure’s load. These foundations are usually not more than 3 meters deep and are commonly employed in residential and small-scale commercial buildings.
• Deep foundations are used when the surface soil lacks the necessary bearing capacity, requiring the load to be transferred to deeper soil layers or rock formations. Types of deep foundations include piles, drilled shafts, and caissons. These are common in large, multi-story buildings and structures like bridges.

The service life of foundations can vary widely, with well-designed and well-constructed foundations lasting upwards of 100 years. Some historical structures, primarily those built on sturdy stone foundations, have stood for several centuries.

Factors That Can Affect the Lifespan:

• Soil Type: The type of soil on which a building is constructed plays a critical role in the foundation’s longevity. For instance, expansive clay can lead to ground movement, affecting the foundation.
• Materials: The quality and type of materials used, such as concrete, steel, or stone, can significantly affect how long the foundation will last.
• Construction Quality: Proper design and quality control during construction are crucial for maximizing the foundation’s lifespan. Errors in construction can lead to premature failure.

 

Building Envelope Component: Roofing

Roofing Type	Average Typical Life	Range	Average Minimum Life	Average Maximum Life
Timber Pitched Roof	85 years	21 to over 100 years	50 years	115 years
Composite Cladding System	40 years	11 to 80 years	25 years	50 years
Plastic Covering to Sheet Roof	30 years	6 to 60 years	20 years	40 years
Aluminum covering to Pitched Roof	35 years	16 to 75 years	25 years	45 years
Insulation to Flat Roof	35 years	6 to over 100 years	20 years	55 years
Galvanized Steel Decking to Flat Roof	35 years	5 to 100 years	35 years	45 years
Copper Sheet Covering	65 years	21 to over 100 years	35 years	80 years
Zinc Sheet Roof Covering	50 years	11 to over 100	30 years	60 years
Steel Covering to Pitched Roof	35 years	11 to 75 years	20 years	45 years
Tile Covering to Pitched Roof	65 years	21 to over 100 years	45 years	105 years
Synthetic Rubber (EPDM) Covering to Flat Roof	25 years	6 to 60 years	15 years	45 years
PVC Covering to Flat Roof	25 years	6 to 80 years	15 years	35 years
Asphalt Covering to Flat Roof	35 years	6 to 100 years	20 years	55 years
Aluminum Decking to Flat Roof	40 years	Less than five to 100 years	30 years	50 years
Softwood Decking to Flat Roof	35 years	11 to over 100 years	25 years	55 years

Adapted from “Life Expectancy of Building Components: Surveyors’ Experience of Buildings in Use; a Practical Guide,” by M. Harvey.

The roof serves function extends far beyond mere aesthetic appeal; it is the first line of defense against various environmental elements like rain, snow, and wind. In this capacity, it serves as a shield that protects the interior of the building from external harm. Extreme weather conditions like high winds, heavy snowfall, and severe heat can take a toll on roofing material, necessitating more frequent maintenance or even early replacement.

In recent years, the roofing industry has seen numerous technological advancements. Roofs are no longer just barriers against the weather; they now accommodate additional features like solar panels for energy generation or gardens for urban agriculture. This multi-functionality makes understanding the service life of a roof all the more crucial for long-term building maintenance and sustainability.

Types of Roofing Materials:

• Asphalt shingles are a staple in residential construction, revered for their affordability and versatility. They come in various styles and colors, allowing homeowners to customize their roofs to match their aesthetic preferences. Despite their cost-effectiveness, asphalt shingles are not to be dismissed in terms of durability. Properly maintained, they can last between 20 to 30 years, offering reliable and long-lasting protection for homes.
• Metal roofing is an increasingly popular option for both residential and commercial properties. Not only do metal roofs have a sleek and modern aesthetic, but they’re also lauded for their durability and longevity. These roofs can last between 40 to 70 years, almost double the lifespan of other common roofing materials like asphalt shingles. Additionally, metal roofs are particularly beneficial for those living in extreme climates. They can withstand severe weather conditions, such as hailstorms and heavy snowfall, better than most other types of roofing materials. They are also more energy-efficient, as they reflect heat and light, reducing the energy costs for air conditioning.
• Slate and tile roofs stand as testaments to both durability and grandeur. Often found adorning high-end residential and historic buildings, these roofing materials offer unparalleled longevity, lasting over a century if properly maintained. However, this exceptional lifespan comes with a significant upfront cost, making these materials more of a long-term investment.
• Flat roofs are common in commercial buildings, but they’re also gaining traction in residential designs, particularly for modern, minimalist homes. These roofs offer the practical advantage of additional usable space for things like HVAC systems or even rooftop gardens. The typical lifespan for flat roofs ranges between 20 to 25 years, but this can extend or shorten depending on the quality of the material and installation.

Service Life and Factors Affecting the Lifespan of Roofs

Understanding the various factors that can influence the lifespan of a roof is crucial for effective maintenance and long-term planning. These factors include the quality of materials used, local climate conditions, and the skill level of the professionals who install the roofing system.

• Climate: Extreme weather conditions like high winds, heavy snowfall, and severe heat can take a toll on any roofing material, necessitating more frequent maintenance or even early replacement.

• Maintenance: A well-maintained roof not only looks good but also functions effectively for a longer period. Regular inspections and timely repairs can extend a roof’s service life significantly.
• Quality of Installation: The skill level of the professionals installing your roof can make a vast difference in its longevity. A poorly installed roof can lead to myriad problems, ranging from leaks to structural weaknesses.

• Insulation Thickness: The effectiveness of your roof isn’t just determined by the exterior materials but also by the insulation that lies beneath them. Adequate insulation thickness is essential for good thermal performance, which can extend the life of the roof by reducing thermal stress and movement.
• Adequacy of Ventilation: A poorly ventilated roof can trap moisture, leading to mold and mildew. Over time, this can weaken the roof structure and reduce its lifespan. In contrast, a well-ventilated roof can add years to the building’s service life by preventing moisture buildup.
• Drainage Capability: Drainage is crucial, especially for flat roofs where water pooling is a concern. A good drainage system can prevent water accumulation, extending the life of the roof.
• Overloading: Overloading due to heavy equipment installation, excessive snow, or debris can cause sagging and structural damage. Regular inspection for signs of stress or deformation can help in taking timely action.
• Moisture Penetration: Moisture is the enemy of longevity when it comes to roofing materials. Effective moisture barriers and regular inspections for leaks can go a long way in extending the roof’s service life.

Whether you’re dealing with asphalt shingles, metal, slate, or other materials, understanding the factors affecting its lifespan is not just academic; it’s a financial and practical necessity. A proactive approach to maintenance can extend the lifespan of your roof, saving both money and resources in the long run.

 

Building Envelope Component: Framing/Sub-Framing

 

Framing Type	Average Typical Life	Range	Average Minimum Life	Average Maximum Life
Steel	85 years	31 to over 100	60 years	115 years
Concrete	80 years	21 to over 100	55 years	105 years
Timber	70 years	16 to over 100	40 years	110 years
Laminated Timber	65 years	16 to over 100	40 years	95 years
Space Frame	75 years	16 to over 100	50 years	95 years

Adapted from “Life Expectancy of Building Components: Surveyors’ Experience of Buildings in Use; a Practical Guide,” by M. Harvey.

 

Let’s move upwards in the structure to framing and sub-framing. If foundations are the roots, then framing is the skeleton of a building. Framing provides the basic structure that defines the shape of the building and serves as a framework to which other components like walls, floors, and roofs are attached. It’s crucial for supporting loads and giving the building its form and stability.

Types of Framing:

• Wood framing is perhaps the most traditional and is widely used in residential construction. It is typically made from softwoods like pine, spruce, or fir and is favored for its ease of use and natural insulating properties.
• Increasingly popular in commercial and some modern residential construction, steel framing offers high strength and durability. It is especially suited for taller structures and is highly resistant to fire, insects, and decay.
• Engineered wood framing includes products like laminated veneer lumber (LVL) and parallel strand lumber (PSL). These materials offer greater strength and stability than traditional wood, while also being more sustainable as they often make use of wood byproducts.

General Lifespan of Different Framing Types

The lifespan of framing varies considerably depending on the material:

• Wood Framing: Typically, wood framing can last anywhere from 80 to 100 years if well-maintained.
• Steel Framing: Steel frames can easily last over 100 years, and with proper maintenance, they can last much longer.
• Engineered Wood: The service life of engineered wood can be comparable to that of natural wood but may offer greater longevity due to its engineered properties.

Factors That Can Affect the Lifespan of Framing

The following factors influence the service life of framing materials:

• Material Quality: The grade and quality of material used will impact how long the framing lasts.
• Environmental Conditions: Humidity, temperature fluctuations, and exposure to elements can have detrimental effects, especially on wood framing.
• Design and Construction Quality: Proper design and construction techniques can mitigate the risks posed by environmental factors and material limitations.

To sum up, the choice of framing material and its maintenance regimen will significantly impact the overall service life of your building. Selecting the right type of framing and adhering to proper maintenance practices can help ensure that the “skeleton” of your building remains healthy for years to come. Given the role that framing plays in providing structural stability, its importance in the longevity of your building can hardly be overstated.

 

Building Envelope Component: Cladding

Cladding Type	Average Typical Life	Range	Average Minimum Life	Average Maximum Life
Plastic Profiled Sheet Cladding	25 years	Less than 5 to 50 years	20 years	35 years
Steel Profiled Sheet Cladding	35 years	6 to over 100 years	20 years	40 years
Glass-Fiber Profiled Sheet Cladding	25 years	6 to 70 years	20 years	35 years

Adapted from “Life Expectancy of Building Components: Surveyors’ Experience of Buildings in Use; a Practical Guide,” by M. Harvey.

 

As we move from the inner structural elements to the exterior, the next component worth examining is cladding. Cladding serves as the outer layer of a building, offering both aesthetic appeal and functional protection. Acting as a skin for the structure, cladding shields the building from weather elements, improves insulation, and often contributes to a building’s architectural character.

Types of Cladding:

• Brick cladding: is one of the most traditional forms and is well-known for its durability and timeless aesthetic. It offers excellent insulation and is highly resistant to environmental wear and tear.
• Vinyl cladding: is a more modern option, popular for its affordability and low maintenance requirements. Available in a range of colors and styles, vinyl is often used in residential settings.
• Metal cladding: usually made from aluminum or steel, is highly durable and often used in commercial or industrial settings. It offers a sleek, modern look and is highly resistant to environmental factors.
• Other types of cladding include stone, ceramic, and composite materials, each with its own set of advantages and disadvantages depending on the application and desired aesthetic.

General Service Life of Cladding

• Brick: Can last over 100 years with minimal maintenance.
• Vinyl: Generally has a lifespan of 20 to 40 years depending on quality and maintenance.
• Metal: Aluminum or steel cladding can easily last 40 to 70 years with proper maintenance.

Factors That Can Affect the Lifespan of Cladding

• Weather Conditions: Extreme temperatures, humidity, and exposure to salt air can impact the lifespan of cladding materials.
• Material Quality: Higher quality materials will naturally last longer.
• Installation: Proper installation is crucial for maximizing the service life of cladding. Incorrectly installed cladding can lead to issues like water infiltration.

Cladding serves as the first line of defense against the external environment and significantly influences a building’s visual appeal. As with other components, the key to maximizing its service life lies in selecting the right material for your needs and adhering to a regular maintenance and inspection schedule. Whether you opt for the classic look of brick, the modern appeal of metal, or the affordability of vinyl, understanding the service life and maintenance needs of your chosen cladding material is crucial for the long-term health and appearance of your building.

Building Envelope Component: Sealants

Sealant Type	Average Typical Life	Range	Average Minimum Life	Average Maximum Life
General Sealant	5 to 20 years	5 to 50 years	5 years	20 years

Adapted from “Whole Life Costing: Sealants”, Greenspec UK; “Structural Silicone Lifespan”, GPD 2017; “Durability of Elastomeric Sealants”, D.H. Nicastro.

Sealants are the unsung heroes of building construction, often overlooked but essential for a structure’s longevity and functionality. These materials act as barriers in various joints and openings to prevent the ingress of water, air, and other environmental elements. From the windows to the roof, sealants are used to ensure airtightness, water resistance, and sometimes even thermal or acoustic insulation.

Types of Sealants:

• Acrylic sealants are water-based and are commonly used for filling gaps in interior walls and ceilings. They’re easy to apply and paint over but are generally less flexible and durable compared to other types.
• Silicone sealants offer high flexibility and excellent weather resistance, making them ideal for external applications like window sealing and expansion joints. They also adhere well to a variety of materials including glass, metal, and plastic.
• Polyurethane sealants are known for their strong adhesion and are commonly used in construction joints, window and door perimeters, and other places that require a durable, flexible seal.

General Lifespan of Various Sealant Types

• Acrylic: Typically lasts between 5 to 10 years, depending on the conditions.
• Silicone: Can last up to 20 years if applied correctly and maintained.
• Polyurethane: Generally has a lifespan of around 10 to 20 years.

Factors Affecting the Lifespan of Various Sealant Types

• UV Exposure: Direct sunlight can degrade the sealant material over time, affecting its efficacy.
• Temperature Fluctuations: Extremes in temperature can cause sealants to expand and contract, potentially leading to cracks or detachment.
• Chemical Exposure: Contact with certain chemicals can degrade the sealant more quickly.

In summary, sealants may not be the most visible elements in a building, but their role is vital. They help maintain the building’s internal environment, prevent water damage, and extend the service life of other components by providing an added layer of protection. Selecting the right type of sealant and adhering to a regular inspection and maintenance regimen can significantly contribute to the long-term durability and comfort of your building.

Building Envelope Component: Windows

Window Type	Average Typical Life	Range	Average Minimum Life	Average Maximum Life
Softwood Windows	35 years	6 to 100 years	20 years	55 years
Hardwood Windows	50 years	16 to over 100 years	25 years	70 years
Aluminum Windows	45 years	6 to over 100 years	30 years	60 years
PVC-U Windows	35 years	11 to over 100 years	25 years	50 years
Steel Windows	50 years	10 to over 100 years	30 years	65 years

Adapted from “Life Expectancy of Building Components: Surveyors’ Experience of Buildings in Use; a Practical Guide,” by M. Harvey.

 

Windows serve multiple functions in a building, from allowing natural light and ventilation to enhancing aesthetic appeal. While their primary role is to provide a visual and physical connection between the building’s interior and the outside world, they also contribute to energy efficiency and comfort when designed and installed correctly.

Types of Windows:

• Single-Pane Windows: are made of a single sheet of glass and are the least energy-efficient among the types. They are commonly found in older buildings and are generally more affordable.
• Double-Pane Windows: consist of two sheets of glass separated by an insulating layer of gas, often argon or krypton. This design improves thermal insulation and is commonly used in modern residential and commercial buildings.
• Triple-Pane Windows: have three layers of glass, offering even better insulation. They are most beneficial in extreme climates but come at a higher cost compared to double-pane windows.

General Service Life of Windows

• Single-pane: Usually last around 20 years, although they might require more frequent maintenance or replacement due to their lower insulating capabilities.
• Double-pane: Can last 25 to 30 years with proper maintenance.
• Triple-pane: Designed to last for 30 years or more, depending on quality and maintenance.

Factors That Affect the Lifespan of Windows

• Material: Windows frames made from durable materials like vinyl or aluminum tend to last longer.
• UV Exposure: Prolonged exposure to sunlight can degrade the sealants around windows and cause the frame material to fade or weaken.
• Environmental Conditions: Salt air, extreme temperatures, and high winds can all affect the lifespan of windows.

Windows play a complex role in the design and functionality of a building. Not only do they affect aesthetics and lighting, but their insulating properties can significantly impact energy costs. Understanding the types of windows and their expected service life can help in planning for maintenance or replacements, ensuring that they continue to serve their purpose effectively over the long term.

Conclusion

Understanding the service life of each component in a building is not just good practice; it’s essential for sustainability and long-term financial planning. A well-maintained building will not only last longer but will also have a lower environmental impact, contributing to broader goals of sustainability. Whether you’re a homeowner, a building manager, or an architectural professional, a deep understanding of the expected service life of each component will equip you with the knowledge to make informed decisions, ultimately leading to buildings that stand the test of time.

By taking the time to understand and plan for the lifespan of each key building component, we can create structures that are not just built to last but are also easier and more cost-effective to maintain. It’s an investment in the future — of the building itself and the communities that surround it.

If you are interested in learning more about service life and building envelope components, please visit our website or contact us today!

 

© 2023 Advanced Architectural Products

 

References:

Harvey, M. (2006). Life expectancy of building components: Surveyors’ experiences of buildings in use: A practical guide (Ser. Royal Institution of Chartered Surveyors). Building Cost Information Service Ltd.

Nicastro, D.H., Feero, Beth Anne. (2016) Durability of Elastomeric Sealants (EIT). The Construction Specifier.

Greenspec Co., UK. (2005) Whole Life Costing: Sealants. https://www.greenspec.co.uk/building-design/sealants-costs/

Wolf, T. Andreas, Recknagel, C., Wenzel, N., Sitte, S. (2020) Structural Silicone: Life Expectancy of more than 50 Years? (Federal Institute for Materials Research). GPD 2017.