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Yes, many trussed roof lofts can be converted. The W-shaped timbers do not make the loft unusable. They mean that the existing roof structure has to be properly re-engineered and supported before any of the truss members are altered.
Absolute Lofts designs and builds trussed roof conversions across London, Essex and Hertfordshire, creating bedrooms, bathrooms and home offices in houses whose owners are often told their loft cannot be converted.
A trussed roof is particularly common in houses built from the 1960s onwards and on later housing developments. The important point is that having a timber trussed roof does not mean your house itself is timber framed. Many trussed roofs sit on completely traditional brick or block-built houses.
If your house itself is timber framed as well as having a trussed roof, the structural considerations can be different. We explain this in our timber framed house loft conversion guide.
Can it be converted?
Yes — many trussed roofs are suitable, subject to survey and structural design.
What matters most?
Usable roof height, a practical staircase, the structure of the house below and a suitable engineered design.
Where do we start?
With your house, its existing structure and the rooms your family actually needs.
It is a common misconception that a W-shaped trussed roof makes a loft conversion impossible.
Many can be converted, but the timber framework forms part of the engineered structure supporting the roof. The internal timbers cannot simply be cut away to make space for a room.
A successful conversion therefore requires a new structural design that replaces the support provided by the trusses being altered while also creating a new structural floor capable of carrying the loft accommodation.
For the homeowner, however, the question is usually much simpler: can we stay in the house we like and create the additional space we need?
You may want:
Those requirements should guide the design from the beginning.
We look beyond the apparent size of the loft. A successful new room needs sufficient usable head height, daylight, comfortable staircase access, sensible furniture positions and a good relationship with the rest of the house.
A trussed rafter roof uses a series of repeated engineered timber frames. These normally contain diagonal members forming triangles inside the roof space.
A very common domestic design produces the familiar W-shaped pattern seen across the loft, although truss designs vary.
When viewed through the loft hatch, all those timbers can make the roof look completely unusable.
However, every diagonal and horizontal member has been positioned for a structural reason. The timbers work together as an engineered unit to support the roof and transfer its loads onto the structure below.
They should therefore never simply be cut or removed to create additional space.
No. This is an important distinction.
A trussed roof describes how the pitched roof has been constructed.
A timber framed house describes the structural construction of the main building from the foundations upwards.
Your house can therefore have a timber trussed roof while the house underneath is built using completely traditional brick or block load-bearing walls.
Traditional pitched roofs were generally constructed on site by carpenters using individual rafters, ceiling joists, purlins and other supporting timbers.
Modern trussed roofs use engineered timber trusses that are designed and manufactured in a factory. The timbers are cut to the required dimensions and joined together, normally using metal connector plates, to create complete structural trusses.
Those completed trusses are transported to the building site, positioned onto the supporting walls and fixed and braced together to form the pitched roof.
This allowed housebuilders to construct pitched roofs efficiently and consistently without having to form the complete roof from individual timbers on site.
As a result, trussed roofs became extremely common in modern housebuilding and are found on huge numbers of properties built from the 1960s onwards.
A typical house with a trussed roof might have:
That house is not a timber framed house.
It simply has a modern method of pitched-roof construction.
This distinction matters when considering a loft conversion because suitable existing masonry walls may be capable of forming part of the structural support for the new loft, subject to the structural engineer checking their position, condition and the support beneath them.
The specialist work can then concentrate primarily on creating the new loft floor and replacing the structural role of the truss members that need to be altered.
Some modern houses have both a timber framed structure and a timber trussed roof.
That creates two separate structural considerations:
With a timber framed property, the structural engineer needs to consider the load path through the whole building and determine where additional steels, posts or other structural support may be required.
This does not mean timber framed houses cannot be converted. We have successfully converted them. It simply means that the structure of the whole building needs to be understood rather than treating the project purely as a roof alteration.
Read our dedicated loft conversions in timber framed houses guide for a fuller explanation.
The internal W-shaped members are part of an engineered structural system.
Removing them without introducing replacement support could weaken the roof because the loads would no longer be transferred in the way the original truss was designed to work.
A trussed roof loft conversion therefore follows the opposite approach.
We install the replacement structural support first. The redundant truss members are altered afterwards in accordance with the structural design.
The structural engineer considers the roof span, supporting walls, house construction, new floor, roof alterations and proposed layout before specifying the solution.
Depending on the property, that may involve:
There is no single standard beam arrangement that suits every trussed roof.
If your house dates from the late 1980s, 1990s or a more recent housing development, there is a good chance that the roof construction is worth checking.
However, the build date alone cannot tell us whether the house has trusses or whether the loft can be converted. Trussed roofs are also found on older properties and housebuilders frequently used different roof designs across the same development.
We regularly receive enquiries from areas such as Bishop’s Stortford, Great Dunmow, Church Langley and other parts of Essex and Hertfordshire, where large amounts of developer-built family housing were constructed during these periods.
These development names identify areas containing substantial amounts of later housing. They do not mean that every property there has a trussed roof or that every loft can be converted.
Housebuilders, house types, spans and roof designs can change between development phases, streets and even neighbouring properties.
One completed Absolute Lofts project demonstrates why a trussed roof should not automatically be dismissed as unsuitable.
The owners of a relatively modern property believed that their loft could not be converted because the roof was filled with W-shaped trusses.
The property itself was also timber framed, so the structural design had to consider both the trussed roof and the way the additional loft loads would be supported through the house below.
An engineer-designed combination of new structural steelwork and A-frame support allowed the existing trusses to be altered safely.
A rear dormer, rooflights and Juliet balcony then helped create a new main bedroom and en-suite bathroom.
Moving the main bedroom into the loft also released the family’s smaller existing bedroom downstairs, allowing it to become a dedicated home office.
This is a good example of the difference between looking at a loft filled with timber and assuming that it cannot be converted, and properly understanding how the structure can be redesigned.
Once the original truss structure has been properly redesigned, the finished accommodation does not need to feel like a compromise.
A properly designed trussed-roof conversion can provide the same sort of comfortable finished accommodation as a conversion in a traditional roof. The important issue is how effectively the available volume is used once the structural work has been completed.
Depending on the available roof space and conversion design, it can create:
Bathrooms can often be incorporated into the higher parts of the new roof space while lower areas are used efficiently for storage.
The finished result should therefore be judged by the accommodation created, not by how obstructed the original roof looked before construction started.
A successful conversion depends on considerably more than whether the trusses themselves can be altered.
During the initial assessment we consider:
The objective should be a useful addition to the house rather than simply creating the largest possible outline within the roof.
A good-sized bedroom with a properly positioned shower room can be far more valuable to a family than trying to squeeze two inadequate rooms into a space that cannot comfortably accommodate them.
The first stage is structural design.
The structural engineer establishes how the roof and new loft floor will be supported after the internal truss members are altered.
Depending on the property, the solution may use steel beams, new timber members or a combination of structural components.
The construction sequence matters just as much as the final design.
The necessary permanent and temporary support is installed before the existing truss members are altered. The W-shaped members are then changed only in accordance with the engineer’s design.
This is specialist structural work. It is not simply a case of removing the timber that is blocking the room.
Once the main structure has been created, the remaining conversion work includes the staircase, insulation, windows, plastering, heating, electrical work, flooring and any bathroom installation.
The fact that a property has trusses does not determine the external type of loft conversion.
The most suitable design depends on the existing roof shape, house type, available volume and planning position.
A rear dormer loft conversion can substantially increase usable headroom and floor area.
It is often worth considering where the existing roof slope would otherwise restrict the bedroom or bathroom layout.
Where the house has a sloping side roof, a hip-to-gable loft conversion can create considerable additional usable space.
A Velux loft conversion may work where the roof already provides adequate height and floor area.
Keeping the outside roof shape relatively unchanged does not remove the need to deal properly with the existing internal truss structure.
On some properties, a combination of dormer space and rooflights gives the best balance between headroom, natural light and external appearance.
There is no reliable fixed price purely because a house has a trussed roof.
The quotation depends on:
Additional structural work can increase the cost compared with converting a straightforward traditional roof, but it is misleading to apply one fixed surcharge to every trussed-roof property.
Our 2026 loft conversion cost guide gives current starting prices for the main types of conversion.
Having a trussed roof does not create a separate set of planning rules.
Many loft conversions to houses can still fall within Permitted Development where the proposed work complies with the relevant limits and conditions and the property’s permitted development rights remain available.
Other projects require planning permission because of their design, scale, location or restrictions affecting the property.
Newer housing developments deserve particular attention because permitted development rights may have been limited or removed by conditions attached to the original planning permission.
A property’s title may also contain a developer covenant affecting external alterations. A restrictive covenant and planning permission are separate matters.
Read our loft conversion planning permission guide for more information.
Where the conversion falls within Permitted Development, we generally recommend obtaining a Certificate of Lawfulness to provide formal evidence of the planning position.
Building Regulations apply separately from planning permission.
For a trussed roof conversion, structural stability is particularly important because the existing engineered roof is being modified and a new habitable floor is being created.
The design needs to consider:
Once the loft becomes habitable accommodation, the fire safety of the whole escape route through the house needs to be considered.
This can include fire-resisting doors and partitions, interlinked smoke detection, a heat detector in the kitchen, protection to the new loft floor and additional measures where the ground floor has an open-plan layout.
Our loft conversion fire safety guide explains these requirements in more detail.
Absolute Lofts has more than 38 years of loft conversion experience across London and the South East.
That experience includes traditional cut roofs, factory-manufactured trussed roofs and timber framed properties where both the roof and the structure of the house below require specialist consideration.
We manage the process from the initial survey through drawings, structural design and approvals to construction.
Most importantly, we do not decide whether a loft is suitable simply because it looks difficult from the hatch.
We inspect the house, understand how the structure works and then establish whether the roof can realistically provide the space the homeowner wants.
You can also explore our completed loft conversion case studies and virtual tours.
No. Many W-shaped trussed roofs can be converted. The roof needs to be structurally assessed and new support designed before the existing truss members are altered.
No. A trussed roof describes the construction of the roof, while timber frame describes the structural construction of the main house. Many traditional brick and block houses have timber trussed roofs.
The roof and the main walls are separate structural systems. Modern roof trusses are engineered timber components manufactured off site and then erected and braced on the supporting walls of the house.
No. The internal timbers are part of the engineered roof structure. Replacement structural support must be designed and installed before the relevant truss members are altered.
Steelwork is commonly used, but the structural solution depends on the individual house. Some designs also use new structural timber and other forms of reinforcement.
Many can. Roof height, roof span, truss arrangement, staircase position and the structure of the house below all need to be assessed.
Yes, in many cases. Suitable existing masonry walls may be used as part of the support for the new loft structure, subject to structural assessment, while the trussed roof itself is redesigned and strengthened.
Yes, in many cases, but the structural design needs to consider both the alteration of the trussed roof and how the additional loft loads will be transferred through the timber framed house below.
It can involve additional structural work compared with some traditional roofs, but there is no reliable fixed premium. The correct price depends on the particular structure and conversion being created.
The most reliable way is to have the property surveyed. We assess the roof height, span, truss arrangement, structure of the house, staircase position and the accommodation you want before recommending a solution.
If you have looked into your loft and seen rows of W-shaped timber supports, do not assume that the space cannot be converted.
Equally, do not assume that all of those timbers can simply be removed.
The right starting point is to understand the structure of the roof and the house beneath it and establish how the new loads can be supported safely.
Absolute Lofts can inspect the property, discuss the rooms you want and explain whether a trussed-roof loft conversion is a practical option.
Call 0800 24 30 48 or request a free, no-obligation survey.