A home’s functionality can be completely transformed by structural changes. A new doorway can enhance circulation without increasing floor size, and removing a wall can transform a small kitchen and compact dining room into a single light-filled family area.
However, these modifications may be some of the most costly and difficult aspects when renovating a house. The amount of wall being removed is not the only factor that affects the cost. It is essential to determine whether it is load bearing, what it supports, and how those loads will be safely transferred. Structural calculations, steel beams, temporary supports, Building Regulations approval, and lengthy making good may also be part of the work.
Here, I explain what can impact costs and what you can expect to pay for the most common structural changes made when renovating or extending.
What to consider when making structural changes
At the most basic level, it might cost between £500 and £1,500 to remove a lightweight partition wall. On the other hand, it could cost between £15,000 and £30,000 or more to open up a large section of a ground floor room or create a substantial structural frame prior to a new kitchen, flooring and decoration being installed.
These price ranges are predicated on standard features and reasonable access, and that the home is a typical one. They are budgetary estimates for labour and materials for homeowners. Since not all builders are registered for VAT, make sure of the VAT position too or double-check with a tax advisor such as Andrew Jones (The VATman) Ltd.
Approval procedures and terminology also differ around the country, plus you should always get written quotes and recommendations for your project.
Removing a non-load-bearing wall
One of the easiest ways to alter a layout is to remove a non-load-bearing wall or partition. It can be used to create a bigger bedroom, connect two smaller reception rooms or connect a kitchen and dining area.
Although some brick walls are not load-bearing, the wall may be constructed from timber or metal studs covered with plasterboard. If a wall seems thin or sounds hollow, don’t assume it can’t support weight. It might support another wall, a section of the roof, or joists. Before demolition, an experienced professional should verify its function.
A basic plasterboard partition can be removed if you’re useful at DIY, after its functionality has been verified. Identify any hidden pipes or cables first, then think about ventilation, escape routes and fire separation. Use a qualified builder to take the wall down if you’re unsure.
Making good can take more time than the demolition, which might only take a day. The demolished wall creates a gap in the floor, and adjacent walls and ceilings require patch plastering.
The combined area may require new flooring because it might be challenging to match dated existing finishes. Before you start working, take a thorough look at both rooms. Once the separating wall is gone, seemingly consistent floor levels, skirtings, ceiling lines and coving may change.
Decide beforehand whether the builder will simply repair the damaged sections or prepare the room for decoration. For simple removal and minimal repair, budget between £500 and £1,500.
If sockets, switches, radiators or plumbing need to be modified, or if more extensive plastering, flooring and decoration are needed, costs could increase to between £1,500 and £3,000.
Removing a chimney breast
In smaller terraced and semi-detached homes, removing an unused chimney breast might free up essential floor space. However, what looks like a straightforward projection in a room might be part of a much broader structure that extends right through the roof, loft and floor above.
You need to decide if you want to remove the breast from the roof, both levels, or just one room. The brickwork above must be supported, possibly by a steel beam, if only the ground floor section is removed. Building Regulations approval is typically required for chimney breast removal, and the support may need to be designed by a structural engineer.
Shared walls may be covered by the Party Wall Act, and additional permission may be required for any external modifications and listed buildings.
Repairing the party wall, installing new floorboards and joists, patching ceilings, replastering, and adjusting services are examples of making good. Soot and old hearths increase mess and disposal costs as well.
To minimise condensation, any remaining flue should be vented. When a chimney is shared, the state and usage of the neighbour’s flue must also be considered. If masonry is removed without first examining the entire layout, structural, damp, and perhaps hazardous flue issues, may result.
Set aside between £2,500 and £5,000 for the removal of a single chimney breast using appropriate support and standard materials. The cost of removing chimney breasts on first and ground floors could range from £5,000 to £9,000. It might cost between £7,500 and £15,000 or more to remove everything through the loft and roof, including scaffolding, roof repairs and weathering features. Major decoration and new flooring are not included in these figures.
Widening door openings
While maintaining some space between areas, widening a doorway can increase accessibility, let in more light into a nearby space or improve the visual connection between two rooms.
When a completely open-plan style would be too costly or difficult, it is frequently a helpful compromise. First you must determine the position of services such as wiring, the existing lintel and the wall construction. There must be enough masonry at both ends of the entrance.
The new lintel or beam in a load-bearing wall requires sufficient support. A lightweight partition can easily be widened, but widening masonry produces more dust and debris and also requires temporary support. When structural loads are involved, DIY work is not sensible. Calculations and approval under the Building Regulations may be necessary.
Before the builder begins, determine the finished opening size. Plaster, linings, a new frame, and the chosen doors must all fit into the structural opening. Compared to a straightforward open archway, pocket doors and glazed screens require more precise setting out and may call for thicker walls.
For a simple opening in a non-load-bearing wall, budget between £600 and £1,500, which includes basic plastering but does not include the door or decoration. It might cost between £1,500 and £4,000 to widen an opening in load-bearing masonry and install a new lintel or small steel beam.
Creating or altering a stair opening
Major layout alterations, basement constructions and loft conversions all involve new stair openings. New trimming joists, beams or steelwork surrounding the stairwell must incorporate the cut joists.
Strength, stair pitch, headroom, guarding and fire safety must all be considered in the design. Additionally, a bedroom or landing may need to be reconfigured to make room for a repositioned stair opening.
Before buying and installing the staircase, budget between £2,500 and £6,000 for the installation and trimming of a standard opening. It can cost between £6,000 and £12,000 or more for complex openings with steel beams, changes to the walls below or restricted access.
For a typical softwood or hardwood domestic flight, the staircase costs may add between £2,000 and £6,000, with custom designs costing significantly more.
Removing a single load-bearing wall
Removing a load-bearing wall is a traditional method of combining two reception rooms or creating a kitchen-diner, but it requires a lot more work than simply removing a dividing wall.
Floors, walls and even the roof above may all be supported. After the wall is removed, such loads need to be carried via foundations, padstones, and supporting walls by a beam.
A structural engineer will determine the loads and design the padstones, beams and bearings. Wider spans may call for paired steels, columns or a goalpost frame, whereas smaller apertures might only need one steel.
Appropriate fire protection is also necessary for the steelwork. When designing the beam, consider its appearance. It is typically easier and cheaper to leave a down stand underneath the ceiling. Although it may need more intricate joist alterations, and extra labour, concealing the beam within the floor area can produce a cleaner outcome.
The builder will install temporary supports before demolition. Because early removal could result in movement, cracking or partial collapse, the correct sequence is essential and sometimes needs to be designed by a structural engineer prior to demolition. It is not a DIY project!
Approval under the Building Regulations is usually necessary, too. Before the steel is covered, building control will inspect significant stages in the construction. Make sure that you retain the completion certificate, approval paperwork and structural calculations for a future sale.
For a standard household opening, budget between £3,000 and £7,500 for the structural work alone. Although quotes will differ on what they include, this should cover demolition, temporary support, a standard steel beam or RSJ (reinforced steel joist) and basic making good.
The cost could reach £8,000 to £15,000 or more in cases involving a huge span, awkward access, more columns, foundation work or a structural frame. The cost of the beam is just one factor. The cost of fabrication, shipping, lifting, temporary works, padstones, fireproofing and making good can be significantly more. Steel components are heavy and seldom show up unplanned through the front door.
The builder can require several operatives, lifting apparatus or steel that is produced in parts and fastened together on site. Any modification to the original design requires the structural engineer’s approval.
Creating larger open-plan spaces
The large kitchen, dining and living space that many renovators desire can be created by opening up the majority of a building’s ground floor. While keeping adequate structure to support the upper floors and roof, it may require removing a few walls, including a combination of lightweight partitions and load-bearing masonry.
A box frame, columns, or interconnected steels may be necessary for supporting large openings. Beneath columns, new foundations may also be specified and designed.
Before you go down this route, however, you should consider both the finished room’s functionality and its appearance. For some families, a fully open layout may be less practical due to noise, cooking odours or the lack of a calm reception area.
Heating controls that are divided into zones may also be important in large areas. For significant structural changes to a typical home’s ground floor, budget anywhere between £8,000 and £20,000.
The cost of a complicated rebuild involving installing many beams, columns and new foundations might range from £20,000 to £40,000 or more. However, large expanses of windows, high-end flooring, a new kitchen and a complete makeover fall outside of these costs and might potentially surpass the structural cost.
If your budget is tight, think about whether a broken-plan arrangement might be more effective than an open one. Glazed doors or partial openings can minimise steelwork while maintaining a sense of separation between spaces.
Structural changes for extensions
Typically, building an extension involves the removal of a section of the existing external wall. A large opening can be an important structural component since it may support the floors, roof and walls above.
While one simple doorway beam may be needed for a little knock-through, structural framework, columns or paired beams may be needed for large openings.
While the space is being created, the current house must remain stable. It may be necessary to divert existing drains that straddle new foundations. Correct connections are required for roofs, floors, insulation, damp proofing and thresholds. It might also be necessary to relocate services on the original external wall.
At the tender stage of the project, access for the steel should be taken into account. The builder could require a crane or telehandler if it is unable to go through the house or around the side. Cost, sequencing, and potentially road permits are all affected by this.
Budget between £4,000 and £10,000 for a simple opening between the house and the extension. The cost of a large side or rear wall opening with extensive fabricated steelwork might range from £8,000 to £20,000 or more.
This does not include the cost of building and fitting out the extension, just the structural modification to the current home.
What things have an impact on structural costs?
There are several factors that can have an impact on how much it will cost to make structural changes to your home:
- Older homes may have undocumented changes, poor foundations, uneven walls or historic movement. Repairing original floors, cornices and plaster is also expensive.
- A timber partition differs greatly from dense masonry, stone or concrete, so wall construction is an important consideration. Strengthening supporting walls might also be necessary.
- The approach taken, and the resulting cost, will be affected by access. Installing a long steel that is carried through a side entry is less expensive than installing one that requires a crane, the removal of windows or additional fabrication. More security is also required for occupied homes.
- Labour, professional fees and disposal are all affected by the property’s location. In parts of the south-east of England and London they might be significantly higher than average.
- Costs associated with design, manufacture and installation are increased by longer spans of steelwork, loads from more than one storey and constrained bearing space.
- A contingency sum is crucial since demolition may potentially uncover wet, rotted joists, shoddy modifications, leaking pipes or wiring that is old and outdated.
Additional costs homeowners often forget
In addition to the structural work itself, there are other costs you need to factor in when planning your budget for the work.
For a simple beam, the cost of a structural engineer can range from £350 to £750. The cost of several beams, frames, drawings and site visits could range from £1,000 to £3,000 or more.
For a minor modification, architectural or technician’s fees for drawings and coordination could range from £750 to £2,000; larger projects would cost more.
Building control fees range from £300 to £900 for a variety of domestic structural modifications. Planning permission is typically not required for internal alterations, although it is necessary for external work and listed buildings. Budget for guidance and possibly also surveyor fees if the work affects a party wall.
Depending on size, location and permits, a skip can cost anywhere from £200 to £800 to hire. Multiple collections may be needed for heavy masonry.
A larger job may also cost an additional £3,000 to £10,000 for plastering, decoration, joinery, flooring, electrics and plumbing. Unless the quotations expressly specify differently, include VAT.
How to budget and cut costs
It’s important to obtain a minimum of four written quotations based on the same scope and drawings, which is always my advice for any tenders. Using a quantity surveyor to produce a schedule of works will assist this process as there is too much room for interpretation in a one-line estimate.
Verify that quotes cover lifting, padstones, fire protection, waste management, temporary supports, steel manufacture and delivery and making good. Carefully define ‘making good’, considering whether surfaces will be prepared for decoration.
Establish a contingency sum of 10 to 15%. For older properties or major unknowns, this amount should be increased to 15 to 20 %. Until the structure is opened up, be sure to keep it separate in your budget.
Verify references, insurance, experience and exclusions. At the tender stage, selecting a qualified structural builder is more important than saving a tiny percentage.
You can potentially reduce costs by minimising needless service changes, maintaining functional wall sections and limiting spans. Before ordering steel, ask the builder and structural engineer to address any concerns you may have. A late modification to a beam length, connection type, or column may result in additional fabrication costs and cause the project to be delayed.
To avoid opening up completed finishes later, it is also important to decide who will notify building control and schedule each inspection.
Instead of organising the task as a collection of separate trades, plan it as a sequence. The proper sequence must be followed for demolition, steelwork, services, plastering, flooring and decoration. A practical plan of action minimises follow-up visits and keeps freshly finished work from getting damaged by the next stage.
Making structural changes to your home is a way to obtain more usable living space without having to move house. Demolition is obviously one cost incurred, but the process also involves structural engineering, temporary support, services, permissions and the finishes that bring the modified rooms back together.
For a more comprehensive picture of the costs you might incur in total, it's worth taking a look at our guide to renovation costs, and for an immediate idea of your potential extensions costs, use our free extension cost calculator.
As a final note, prior to any structural changes, let your house insurer know that you are carrying out the works as this may cover you in the event of any issues that may arise. Depending on the scale of the work, you may need to take out specialist renovation insurance.
It’s also worth taking out a structural warranty for major works with companies like Self Build Zone. With the right consideration and good design, well-planned structural changes will add value in the long term for your project.
