Rafters vs Trusses: What’s the Difference?

When building or renovating a roof, one of the first decisions you’ll face is whether to use rafters or trusses. Both serve the same core purpose - supporting your roof’s structure - but they differ greatly in how they’re designed, built, and installed. Choosing between them isn’t just about cost; it affects the strength, aesthetics, and flexibility of your entire roofing system. Below, we’ll explore the key differences between rafters and trusses so you can make an informed decision for your next project.

What Are Rafters?

Rafters are the traditional method of roof framing, used for centuries before prefabricated trusses became popular. They are individual sloped beams, typically made from timber, which run from the roof ridge (the highest point) down to the wall plate on the external walls. Each rafter supports the roofing material above while helping distribute the roof’s load evenly across the structure. A rafter roof is usually built on-site, beam by beam, by a skilled carpenter or roofer.

Key Features of Rafters

Rafters are constructed on-site, which allows for flexible design and custom roof shapes. They are typically made from solid timber, although engineered wood or steel may also be used. One of their biggest advantages is that they allow for open loft spaces or vaulted ceilings, giving you more freedom in interior design. Because rafters are built to specification, they’re ideal for projects where the roof needs to match a unique architectural style or where usable loft space is desired.

What Are Trusses?

Roof trusses are a modern alternative, made up of multiple timber members joined together in a triangular framework. They’re usually prefabricated off-site in specialist factories, using precise engineering to create a lightweight yet incredibly strong structure. Once built, the trusses are delivered to site and lifted into position. Trusses are now the most common roofing system in new builds, especially in residential developments, because they save both time and labour costs.

Key Features of Trusses

Trusses are prefabricated for fast installation and consistent quality. They’re designed using advanced structural engineering, meaning less on-site cutting and measuring. Because of their interconnected design, trusses spread the load efficiently across the walls and provide exceptional strength. However, the downside is that they typically limit usable loft space due to the internal webbing that runs through the middle of the structure.

Rafters vs Trusses: The Key Differences

1. Construction Method

The most fundamental difference lies in how they’re built. Rafters are constructed piece by piece on-site, giving flexibility but requiring skilled labour and more time. Trusses, on the other hand, are prefabricated in a controlled environment and then installed as complete units. This makes trusses faster to install and less dependent on on-site craftsmanship.

2. Cost and Labour

Cost is often a deciding factor. Rafters generally require more timber, more labour hours, and more expertise. They can be expensive for large projects, though they make sense for bespoke builds or renovations. Trusses are more cost-effective on average because they’re mass-produced and quicker to install, reducing both labour costs and build time.

3. Strength and Load Capacity

Trusses are designed for high load-bearing performance, with a triangular configuration that offers excellent structural stability. This makes them ideal for large spans, commercial buildings, or homes where minimal internal support walls are desired. Rafters are strong too, but they don’t match the uniform load distribution of a trussed roof, especially on wide spans.

4. Design Flexibility

Rafters provide much more freedom in roof shape and pitch. Whether you’re creating a steep, high-pitched roof or a complex multi-gable design, rafters can be adapted easily. Trusses are more limited since they’re manufactured to a fixed design; any customisation typically requires a new engineering drawing and additional cost.

5. Attic and Loft Space

If you want usable loft or attic space, rafters win hands down. Their open structure allows for storage or conversion into living areas. Trusses usually have internal webbing that blocks usable space, although attic trusses can be engineered to include open sections if needed - but that comes at a higher cost.

6. Speed of Installation

Because trusses arrive ready to fit, installation is quick and efficient. In a matter of days, a full trussed roof can be in place, saving time and reducing exposure to the elements. Rafters take significantly longer to construct since each beam must be measured, cut, and installed individually.

7. Maintenance and Longevity

Both options are durable if built and maintained properly. Trusses, thanks to precision manufacturing, tend to be more consistent in quality. Rafters, meanwhile, rely on the skill of the installer. Over time, either system can last for decades, provided they’re protected from moisture, pests, and structural movement.

When to Choose Rafters

Opt for rafters if you’re building a custom home, renovating a period property, or planning to convert the loft into a living area. Rafters suit smaller projects where bespoke craftsmanship and aesthetic detail matter more than speed or cost-efficiency. They’re also ideal if your design requires a complex or irregular roof shape that prefabricated trusses can’t accommodate.

When to Choose Trusses

Choose trusses for modern, large-scale, or time-sensitive projects. They’re perfect for developers, builders, and homeowners who need a reliable, strong roof that can be installed quickly. Trusses also make sense when you want to minimise load-bearing walls, as their engineered strength allows for larger open-plan spaces below. 

Environmental and Material Considerations

Both rafters and trusses can be made from sustainably sourced timber. However, trusses are often more efficient in material usage because their design minimises waste. Many suppliers use FSC-certified timber and computer-aided design to optimise cuts, reducing environmental impact.

Which is Best for Your Project?

If your goal is architectural flexibility and future loft space, rafters are worth the investment. If you want a cost-effective, structurally consistent, and quick solution, trusses are the smarter choice. In practice, the decision often depends on your project’s priorities - whether that’s speed, budget, design, or long-term usability. 

For most new builds in the UK, trusses have become the standard due to their efficiency. But for self-builders or those renovating traditional homes, rafters remain a timeless option that adds character and design freedom.

Final Thoughts

Whether you choose rafters or trusses, it’s essential to consider your overall roof design early in the project. Factors like roof pitch and materials can significantly affect which system suits your property best. For more insight, read our guide on how roof pitch affects choice of roofing material.

And when it comes to finishing your project, explore our best selling roof tiles for pitched roofing to complete your roof with quality and style. Whether you’re working with rafters or trusses, the right tile will ensure performance and aesthetics for years to come.