Breaking down everything you need to know, from understanding the structure to budgeting, planning, and designing your dream space. We've got you covered whether you're exploring costs, feasibility, or the construction process.
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Yes, you can convert a truss roof loft. It just takes a bit more structural work than other types of lofts. That’s because truss roofs are supported by a crisscross of timber beams (called webs) that run through the middle of the loft, making the space awkward to use as it is.
To open things up, those supports usually need to be replaced with steel beams, providing a clear, usable area without compromising the strength of your roof. It may sound complex, but with the right team, it’s completely achievable, and the results can be truly amazing.
Here’s a quick look at what to expect and where to find more info:
A truss roof is a type of roofing system commonly found in homes built after the 1960s. Instead of using traditional timber rafters, it’s built with prefabricated triangular frames, known as trusses, which are designed to support the roof's weight evenly.
These trusses are lightweight, cost-effective, and quick to install, which makes them a popular choice. But while they’re great for keeping costs down during construction, they do come with a catch, the internal supports (called webs) run right through the loft space.
This network of diagonal beams gives the roof its strength but makes it difficult to use the loft without some structural changes.
If you're considering converting your loft, it’s helpful to understand the type of roof you have and how the trusses might impact the layout, headroom, and build cost.
Not all truss roofs are built the same. There are several variations, each with its layout, strengths, and potential challenges when it comes to converting your loft.
Knowing which type you have is a helpful first step. It can help you understand what structural work might be needed, how much usable space you’ll gain, and whether a conversion is realistic without major changes.
Below, we’ve broken down the most common types of truss roofs and what each one means for your loft plans.
Fink trusses are the most common in homes built after the 1960s. Their signature W-shaped web of supports makes them strong, affordable, and easy to install.
However, the dense framework of diagonal beams can take up a lot of space, making loft conversions more complicated.
Here's a detailed image of the structure to get an idea of the signature "W" structure.
King post trusses are a simpler design with two sloping beams (top chords) and a single vertical post in the centre for support. These are often used in smaller spaces, like garages or extensions. Their straightforward structure means they’re usually easier to modify for a loft conversion compared to more complex designs.
Queen post trusses are like an upgrade to the king post. Instead of one vertical post, they use two, allowing for wider spans and a bit more open space in the loft. This makes them more suitable for loft conversions in homes with larger roofs.
Howe trusses feature a mix of vertical and diagonal supports, making them very strong and ideal for longer roof spans. While they’re great for stability, the dense network of beams can limit open loft space and make conversions more challenging without significant modifications.
Raised tie trusses are designed with the bottom beam (tie) positioned higher than usual. This creates more headroom, a huge bonus if you consider converting your loft.
Raised tie trusses are often a better conversion starting point than other types.
Scissor trusses create a vaulted or cathedral-style ceiling, with the bottom beams angling upwards instead of flat. While they’re less common in standard homes, they’re great for adding a spacious and unique look to loft conversions.
A truss roof loft conversion is often more involved than a standard loft project, and that shows in the price. Due to the additional structural work required to open up the space, the project typically incurs higher costs to complete.
Most truss roof loft conversions in the UK fall within a range of £30,000 to £60,000. The exact figure depends on the size of your loft, the extent of structural work required, and the type of finish you're aiming for.
If your loft doesn’t meet the minimum head height, you might need to raise the roof or lower the ceilings below, which adds to the cost. The final price can also rise if you opt for high-end materials, built-in storage, or an en-suite.Knowing where the costs originate helps you plan and avoid surprises during the construction process.
While most conversions fall within a typical range, certain factors can cause the price to increase. It usually comes down to how much structural work is needed and how ambitious your plans are.
Here are some of the main things that can increase the overall cost:
If you’re short on space and want to stay in your current home, converting a truss roof loft is often a smart move. While the upfront cost may be higher than a standard conversion, it’s usually still significantly more affordable than relocating to a new house.
You’ll also be adding value. A well-designed loft conversion that includes a bedroom and bathroom can increase your home’s market value by up to 20 per cent, depending on location and quality of finish.
Beyond the numbers, you’re turning previously unused space into something genuinely useful, whether that’s a quiet home office, a guest room, or a new master suite.
Converting a truss roof loft is perfectly doable, but it takes more planning and structural work than a standard loft conversion. Below is a simple breakdown of what to expect at each stage so you can move forward with confidence.
The first step is a structural survey. A qualified engineer will assess the construction of your existing roof and determine the safest method for removing or replacing the internal timber supports. These supports, often arranged in a W shape, give the truss roof its strength but get in the way when you’re trying to create usable space.
To solve this, steel beams are usually installed to take over the structural load. At the same time, you’ll work with a designer or loft conversion specialist to plan your new space. This includes deciding where the staircase will go, how much headroom you’ll have, and what kind of layout will work best.
If the existing loft space is too low, you may need to raise the roof or lower the ceilings below to meet building regulations.
Truss roof loft conversions often fall under permitted development, which means you don’t need full planning permission. However, this depends on your property type and whether you're altering the roof height or structure. If you live in a conservation area or plan to make major changes to the exterior of your home, you may require formal approval.
Regardless of whether planning permission is needed, building regulations always apply. These rules cover structural safety, insulation, fire escapes, and energy efficiency. Your builder or loft company will usually handle the paperwork, but it's worth understanding what needs to be signed off.
This is where your loft begins to transform. The internal timber braces that make truss roofs difficult to convert are carefully removed and replaced with steel beams, often referred to as RSJs. These beams span the width of your loft, carrying the weight of the roof and allowing the space to open up.
The work needs to be done gradually and with precision, typically throughout a couple of weeks. Once complete, you’ll be left with a clear, strong loft space ready for the next stage.
With the structural work complete, your conversion proceeds to the build phase. This includes fitting insulation, electrical wiring, plumbing if needed, plasterboarding, and installing the staircase. Once that's in place, the loft will be ready for flooring, windows, paintwork, and any bespoke features you’ve planned.
This part of the process feels much more like a typical home renovation and usually takes a few weeks to complete. Ultimately, your new space will look and feel just like any other room in your home.
Most truss roof loft conversions take between eight and twelve weeks from start to finish. The most disruptive stage is usually the installation of steel beams, especially if ceiling work is required below. However, experienced builders know how to minimise disruption and keep the rest of your home livable during the build.
While converting a truss roof loft is possible, it often comes with a few extra hurdles. These roofs are designed for efficiency and strength, but not for creating open, usable space, which means specific adjustments are typically required before a full conversion can proceed.
Below, we’ve outlined the most common challenges that come with truss roof lofts, along with the typical solutions that experienced builders use to overcome them.
