Everything you need to know about pitched roofs

Thanks to their visual appearance, durability and weather resistance, pitched roofs remain the most popular choice for residential and many commercial properties. When it comes to specifying and building pitched roofs, there is often a lot more to consider than many people may realise, and Marley’s team of roofing experts is here to help you with every aspect of the planning, design, construction and regulatory compliance. In this guide, we'll cover all the basics of what you need to know about pitched roofs – from what they are to why they are so popular, how they are constructed and what regulations must be considered when planning and installing them.

What is a pitched roof?

Technically, a pitched roof is any roof over 10 degrees and a flat roof is classed as anything 10 degrees or lower. Most roofs between 10 and 15 degrees tend to be covered in flat roofing materials or metal sheets, whereas most roofs of 15 degrees and over tend to be covered in roof tiles.

The angle of a roof pitch can vary significantly depending on architectural style, aesthetic preferences, climatic conditions and other functional requirements – such as the amount of vertical clearance desired in the roof space.

• A “normal” roof pitch is typically anything from 20° to 45°. Roofs outside this range may require different structural or design elements to ensure safety and weather resistance.
• If a roof is over 45°, it is normally considered to be a steep pitch.
• A roof pitch less than 20° is normally considered to be a low-pitched roof.

What makes a roof pitched?

Physically, the roof pitch is “made” by the angle of the rafters or trusses.

• Rafters are structural timbers that extend downwards from the highest point of the roof plane (typically the ridge) down to the eaves, where the roof meets the walls. At this point, the roof load is transferred to the walls.
• Trusses are pre-engineered frames typically made of timber or steel. Usually triangular, they span the entire width of the roof and distribute the load evenly across the structure.

Stuart Nicholson, director of roof systems here at Marley, notes that the relationship between the height of the roof ridge and the size of the building’s footprint also plays a role in the roof's pitch. He explains: “If the roof has a higher ridge and a smaller footprint, it will have a steeper pitch; a roof with a lower ridge with a larger footprint will have a shallower pitch. Steeper roofs are often designed to incorporate one or more habitable rooms, and/or show off more aesthetically pleasing roof coverings such as clay pantiles or natural slates”

Types of pitched roofs

The external shape of a pitched roof can vary significantly, depending on architectural style and design preferences. Common types of pitched roofs include:

• Gable to gable roof: A gabled roof has two sloping sides that meet at a ridge, resulting in a triangular gable at each end. The free edges of the roof above the gable ends are called verges. This is a traditional and aesthetically pleasing type of roof. It’s also simple to build, allows for efficient water drainage, is low risk with regards to water ingress, easy to ventilate and insulate, and can provide a large internal roof space.
• Hip roof: Hip roofs normally have four slopes that meet at the ridge, creating a compact and balanced appearance. The sloping line where two roof slopes meet is known as a hip and is often covered in ridge/hip tiles. This construction distributes weight evenly, helping to make hip roofs stable, is low risk with regards to water ingress, resistant to high winds and ideal for exposed locations.
• Mansard roof: Mansard roofs have steep lower sections, often over 60 degrees and shallow upper sections. The design is very striking and allows for large areas of the building to be covered in roof coverings rather than brickwork. It also allows for an increased amount of living space in the roof. Mansard’s can be more complicated to construct than the other roof types, so specialist advice is generally recommended.
• Mono-pitch roof: With a single roof slope that creates an asymmetric appearance, mono-pitched roofs are a popular choice for buildings with a more modern appearance. Mono-pitch roofs which are built against a wall are more commonly known as lean-to roofs and are a common feature on home extensions.
  Often, buildings incorporate more than one type of pitched roof. For example, an L-shaped house might feature a gable roof over one part of the structure, which connects to a hip roof at a right angle. L shaped, and T-shaped roofs will need to include valleys to guide the water from the inward facing roof slopes down to the eaves and into the gutters. The risk of water ingress is higher at the valleys, so it is important to ensure they are designed and constructed correctly for the pitch, the size of the roof, the location and the type of roof covering.

Types of pitched roofs – roof build-up

Internally, pitched roofs can also differ in structure. The choice of roof build-up can affect insulation and thermal performance. Two common types are cold pitched roofs and warm pitched roofs.

 

• Cold pitched roofs: In a cold roof system, the insulation is located between or directly above the ceiling joists, insulating the living space below but not the roof space above. Cold roofs tend to be specified when there is no requirement for a habitable room in the roof space, they tend to be less expensive to build but can be less energy efficient than warm roofs.
• Warm pitched roofs: In a warm roof, the insulation is installed at rafter level. This means that the roof space is insulated along with the living space below. Warm roofs usually cost more to build, but are generally considered to be more energy efficient, so they can save money in the long term. The insulated roof space can also be used for storage or converted into an occupied space.

 

Stuart notes that some roofs may incorporate sarking boards. “Sarking is a protective layer of softwood that’s installed between the insulation and the roof covering,” he explains, adding: “Sarking is more common in Scotland, as it provides extra protection in extreme weather conditions.”

Types of pitched roofs – roof covering

Most people think of the roof covering as a protective layer that shields the building from the elements such as wind and rain, but actually you should consider the aesthetic options available as the roof is often the most visible façade. But, while appearance is an important consideration when choosing a roof covering, it’s also important to remember that the choice of roof covering will also impact the performance and longevity of the structure. In the UK, common pitched roof coverings include:

• Clay tile: A classic option that provides a traditional appearance, clay roof tiles are provided in a variety of styles and textures, from S-shaped pantiles to Plain tiles, both of which provide a long lasting, aesthetically pleasing, and traditional appearance to the roof and the overall property, something often referred to as ‘kerb appeal’. Indeed, spending a little more on the roof can leave a big impression on buyers as it marks the roof and the building out as being of a higher spec. The main benefit to clay is that its natural colour ages beautifully over time and lasts for the life of the tiles.
• Concrete tile: Manufactured to replicate the appearance of clay tiles or slates, concrete roof tiles tend to be more affordable than clay tiles. The sheer range of colours and profiles (some of which provide a slate or plain tile look for the fraction of the cost) and their affordability means that concrete tiles are by far the biggest seller in the UK. However, over time, their colour may fade.
• Timber shingles and shakes: Typically made from cedar, timber shingles and shakes are a renewable option that’s also lightweight and provides a unique charm. The main difference between shingles and shakes are that shakes are a relatively smooth finish because they are sawn when manufactured, and shakes offer a much more textured finish because they are split.
• Slate: A natural material known for its durability and appearance, slate roofing is a traditional option made from a natural material known for its durability and good looks. The quality of natural slate can vary tremendously so it is always best to consult an expert with regards when specifying this type of roof covering.

Beyond traditional roofing materials, various roof elements can be incorporated into a pitched roof:

• Integrated solar tiles: Designed to function as both a roof covering and solar energy collectors, integrated solar panels – such as the Marley SolarTile® – provide a seamless appearance and a low-carbon electricity supply. Integrated solar panels are best suited to full re-roofing project or new roofs where all the materials are new together so that the whole roof has a life expectancy of 60 years.
• On-roof solar tiles: These are normally installed on top of existing pitched roofs as a retrofit, rather than replacing roofing tiles or slates. Care should be taken to ensure the roof structure is suitable and is not damaged during installation and that the roof covering is left as secure and weatherproof as before the panels are installed.
• Rooflights and roof windows: These allow natural light to enter the building, enhancing the appearance inside and out, while also reducing the need for electric lighting.
  
  

What are the best applications for pitched roofs?

Thanks to their weather resistance, timeless good looks and ease of building, pitched roofs are used across a wide range of building types, including:

• Residential – Pitched roofs are the most common type of roofing for residential houses and are often used on blocks of flats.
• Heritage and conservation projects – Pitched roofs have been used for thousands of years, so they are often found in historic and conservation projects.
• Commercial and mixed-use developments – Opting for pitched roofs in commercial and mixed-use developments can make the buildings look more attractive and welcoming.
• Industrial and agricultural buildings – From factories and warehouses to workshops and barns, many industrial and agricultural buildings use pitched roofs due to their low maintenance requirements and excellent weather performance.

What are the key components of a pitched roof?

Pitched roofs combine several elements, all of which work together to protect the building and give it the desired aesthetic.

• Roof covering – Options include concrete tiles, clay tiles, timber shingles and shakes, slate or metal. Some solar panels – such Marley SolarTile® – can also be used as part of the roof covering.
• Battens – These timbers run horizontally across the roof, parallel to the ridge, and provide a fixing point for the roof tiles. They are also often used as footholds for roofing contractors, so high-quality battens, which must be stamped and comply with BS5534, are essential for safety, as well as the roof’s long-term performance.
• Underlay – Also known as a roof membrane, the roof underlay sits under the roof tiles and provides a secondary layer of weather protection. Underlay can be air-impermeable (often known as non-breather) , vapour permeable, or air and vapour permeable (often known as breather membranes). Note that the type of underlay chosen should be capable of being installed in the wind-loading location of the building and be installed and ventilated as specified by the manufacturer.
• Sarking – More commonly used in areas with extreme weather conditions, sarking is a protective layer of softwood that is installed above the rafters.
• Roof trusses or rafters – These are the structural timbers that support the roof covering.
• Insulation – Roofs should be well insulated to maintain the building's thermal efficiency.
• Ventilation – Adequate ventilation is essential for avoiding condensation, mould and mildew. Most pitched roofs will have ventilation along the ridge and eaves depending on the roof design.
• Flashing – A protective layer that prevents water ingress, flashing is installed around joints and roof penetrations like chimneys, dormers and rooflights. Often lead or a lead-replacement product although plastic and hard metal flashings can be used.
• Guttering and drainage – Gutters, eaves systems and valleys all help to channel water downwards and away from the roof.
  
  

How do pitched roofs protect a building?

Pitched roofs protect the building structure, its contents and the occupants against environmental factors such as wind, rain, snow and moisture ingress. They also provide thermal insulation and protect buildings from vermin and insects. Pitched roofs additionally protect the overall structure to help ensure long-term performance.

Standards and regulations for pitched roofs

When designing and constructing a pitched roof, compliance with relevant building standards and regulations is crucial. Key standards to consider include:

• BS 5534:2014+A2:2018, the code of practice for slating and tiling for pitched roofs and vertical cladding – This covers installation and material specifications, including the requirements for dry-fix roofing.
• BS 5250:2021, the code of practice for the management of moisture in buildings – It provides guidance on roof ventilation and preventing condensation.
• NHBC Standards 2025 – This document is used by housebuilders to ensure roofs meet the criteria required by warranty providers.

The Building Regulations: How do Part L, Part F and Part O impact pitched roof design?

As well as the roofing standards mentioned above, there is also building legislation to consider.

The legislation for construction has been devolved across the UK nations, with each country having its own set of requirements and guidance documents. These are:

• England: Building Regulations (2010) and Approved Documents
• Wales: Building Regulations (Wales) and Approved Documents
• Scotland: Building (Scotland) Regulations and Technical Documents
• Northern Ireland: Building Regulations (Northern Ireland) and Technical Booklets

The legislation and guidance in these documents is similar, but with some differences, so it’s always important to check the guidance as it applies to a specific project. Below, we’ll be discussing the requirements in England.

Several parts of the Building Regulations apply to roofs. Approved Document B (fire safety) discusses issues such as compartmentation and fire ratings of roofing materials. Approved Document A (structure) aims to ensure that roofs can support expected loads and includes the requirements for the structural timbers.

Three parts of the building regulations, Part L, Part F and Part O, specifically provide advice for aspects relating to energy efficiency.

• Approved Document L (Conservation of fuel and power) sets standards for thermal efficiency for the entire building envelope, including pitched roof
• Approved Document F (Ventilation) requires adequate ventilation throughout a property, thereby preventing condensation and improving indoor air quality.
• Approved Document O (Overheating) only applies to residential properties and aims to reduce solar gains on the property, primarily dealing with glazed elements. It doesn’t directly relate to pitched roofs, but if rooflights or skylights are included in the roof design, Approved Document O should be consulted.
  
  

Stuart adds that the next changes to the Building Regulations are expected in 2025, when the Future Homes Standard (FHS) comes into effect. “This update will likely involve revisions to Parts L, F and O, aiming to ensure all new homes in England produce 75–80% fewer carbon emissions compared to those built under previous standards,” he explains. “Stricter requirements for the building envelope will ensure that all parts of the building – the pitched roof, walls and floor – are all as thermally efficient as possible.”

Need expert advice about a pitched roof? Talk to Marley

Whether you’re planning pitched roofs for a new housing development, a single home or a commercial or industrial property, the team at Marley is here to help. Our Roofing System has been designed for compatibility between components and easy specification – and we offer a wide range of clay and concrete roof tiles, cedar shingles and shakes, roof ventilation products, dry-fix systems, underlays, battens and more.

To learn more about our range of products, download a brochure or contact a member of our team for support on your next pitched roof project.