Shell (Structural Only) Loft Conversion
A shell loft conversion, sometimes called a structural only or first fix conversion, covers the structural build and leaves the interior finishing to you. You get the new floor structure, any roof alterations or dormer, the windows, and a weathertight structure, but plastering, flooring, decorating and often the final electrics and plumbing are left for you to arrange separately, either yourself or through your own tradespeople.
This approach suits homeowners who want to spread the cost of a loft conversion over a longer period, or who already have trusted electricians, plumbers or decorators they would rather use for the finishing stages. It is also common with landlords and homeowners planning to finish the space to a particular specification themselves, rather than paying for a full fit out they may want to change later.
There is one important point worth understanding before choosing this option. Building Control needs to inspect and sign off the structural elements, the floor joists, any load bearing changes, roof insulation and the roof alterations themselves, while that work is actually being done. If these structural elements are not built and inspected correctly at the shell stage, it can be difficult or impossible to get the finished room signed off as habitable later, even after everything else is complete. Getting the shell right, and properly inspected, is what protects the value of finishing the room yourself further down the line.
Who this for
This service suits homeowners who want to manage their own budget and timeline for the interior finish, including those planning to use their own tradespeople for plumbing, electrics or decorating, and landlords or homeowners renovating in stages. It is worth being realistic about the work still involved once the shell is complete, since a genuinely habitable room needs compliant insulation, a fire escape route and a proper staircase before Building Control will sign it off.
Shell (Structural Only) Loft Conversion Cost
A shell loft conversion typically costs £10,000 to £20,000, considerably less than a fully finished conversion, since you are paying for the structural build only. Per square metre, this usually works out at £700 to £1,350, well below the £1,600 or more per square metre you would expect from a fully finished dormer or mansard. A simple shell conversion using velux windows rather than a dormer, on a roof that already has enough head height, can come in as low as £10,000 to £12,000. What counts as shell varies between builders, so it is worth being clear about exactly what is included before you compare quotes. Some shell packages include first fix electrics and plumbing ready for a second fix later, others do not. We will set out exactly what is and is not included in your quote, so there are no surprises once the structural work is complete and you move on to finishing the room yourself. Get in touch for a free survey and a clear, itemised quote showing exactly where the shell stage ends and the finishing work begins.
Project Process Steps
We survey the roof and agree the structural design, whether that is a dormer, a hip to gable conversion, or velux windows only, along with exactly what will and will not be included in the shell.
We handle the structural build, including new floor joists, roof alterations, and steel beams where needed, with Building Control inspecting and signing off each structural stage as the work progresses.
We complete the shell to a weathertight standard, including the roof covering, external finish and windows, so the space is fully protected from the weather even before any interior work begins.
We hand the space over to you with a clear record of what has been inspected and signed off, so you or your chosen tradespeople know exactly what stage the room is at before finishing work begins.
Frequently asked questions (FAQ)
What is included in a shell loft conversion?
This generally covers the structural build, new floor joists, roof alterations or a dormer if needed, steel beams, windows and a weathertight external finish. It does not usually include plastering, flooring, decorating or the final fit of electrics and plumbing, though this can vary, so we confirm exactly what is included before you agree to a quote.
Can I finish the room myself after a shell conversion?
Yes, this is exactly what a shell conversion is designed for. Many homeowners bring in their own electrician, plumber and decorator once the structural shell is complete, or complete some of the finishing work themselves.
Will the room be signed off by Building Control straight away?
Not fully. Building Control will inspect and sign off the structural elements as they are built, the floor, roof alterations and insulation, but a room is only signed off as fully habitable once it also has a compliant staircase, a proper fire escape route and the interior finishing is complete. This is why getting the structural stage inspected properly matters, even though the room will not be finished straight away.
Is a shell conversion cheaper overall than a fully finished one?
The shell stage itself is cheaper, since you are only paying for the structural build. Whether the whole project ends up cheaper depends on what you spend finishing it yourself, so it is worth costing out the finishing stage honestly before assuming it saves you money overall.
Can I upgrade from a shell to a fully finished conversion later with the same company?
In many cases, yes, and it can be simpler to have the same company that built the structural shell come back to finish it, since they already know the specification and the inspection history. Get in touch to discuss finishing options whenever you are ready to move forward.