Rewiring an old house in the UK — what's involved

The short answer

Rewiring an old or period property is usually slower and more expensive than a modern home, because the construction makes running cable harder. Solid masonry walls, lath-and-plaster ceilings, no cavity, and timber or concrete floors all mean more chasing, more lifting and more making good. Older homes also more often have degraded rubber or fabric cable, no earthing to some points and an outdated fuse board, so a full rewire is more likely to be recommended. Additional care applies to listed buildings and conservation areas, where consent may be needed and routes must avoid damaging historic fabric. An EICR is the sensible starting point to establish the installation's actual condition.

Period homes are rewarding to live in but unforgiving to rewire. The sections below explain why the job costs more, what tends to be found, and the permissions to check before work starts.

Old-house factors

WallsSolid, no cavity
CeilingsOften lath-and-plaster
Common faultsPerished cable, no earth
Listed buildingConsent may apply
First stepAn EICR

Why old houses cost more to rewire

A rewire is labour-led, and period construction adds labour at almost every step:

Solid walls with no cavity: there is no void to feed cable through, so channels must be chased into masonry and replastered, which is slower and messier than a modern stud or cavity wall.
Lath-and-plaster ceilings: fragile and awkward to work above, increasing the risk of damage and the time to run cables for lighting.
Suspended timber or solid concrete floors: timber floors mean lifting and relaying boards; concrete floors may force cable into surface trunking or skirting.
More making good: chasing solid walls and disturbing old plaster means a larger replastering and redecorating bill than a newer home.

The result is that the same number of rooms can cost more in an old house than in a modern one, with the difference largely in access and making good rather than the wiring itself.

It is worth being clear about where that extra money goes, because it changes how you read a quote. The cable, accessories and the electrician's wiring labour are broadly similar to a modern home of the same size; what inflates the figure is everything around the wiring — the slow, careful chasing of solid masonry, the extra protection and reinstatement of fragile lath-and-plaster, and the larger replastering and redecorating bill at the end. That means the biggest variable in an old-house rewire is often the making good rather than the electrical work, and it is the part most likely to be quoted separately or by a different trade. Pinning down who is responsible for plastering and decoration, and whether it is inside or outside the headline figure, is the single most useful thing you can do to avoid a nasty surprise on a period property.

Budget for making good: in a period home the plastering and redecorating after chasing solid walls can be a significant share of the total. Confirm whether quotes include making good or treat it as a separate trade.

What an EICR typically finds in an older home

Older installations more often carry the faults that point towards a rewire. An Electrical Installation Condition Report (EICR) commonly identifies:

Degraded cable insulation — perished rubber, lead-sheathed or fabric-covered cable that has hardened and cracked.
No or inadequate earthing to lighting circuits or accessories.
An outdated consumer unit with rewireable fuses and no RCD protection.
Too few sockets, leading to overloaded extension leads.
Past alterations that do not meet current standards.

Where these appear across many circuits, or the cable itself has degraded throughout, a full rewire is usually the sensible outcome. Where the installation is fundamentally sound, targeted repairs and a consumer unit upgrade may suffice. The EICR codes — C1, C2, C3 and FI — give the evidence for that decision rather than relying on age alone.

Old houses also tend to carry a history of piecemeal alterations that complicate the picture. Decades of added sockets, extended lighting circuits, replaced boards and DIY work — not all of it to the standard of its day, let alone the current one — leave an installation that is really several generations of wiring spliced together. An EICR on a period home therefore often finds a patchwork: sound modern PVC on circuits that were redone, alongside perished rubber on the runs that never were. This is part of why the inspection matters so much in an older property. The headline question is rarely "is the whole house dangerous?" but "which parts have reached the end of their life and which are fine?" — and the answer to that is what decides between a full rewire and a more targeted job, in a way that the building's age on its own cannot.

Listed buildings and conservation areas

An extra layer applies to listed buildings and homes in conservation areas. Listed building status protects the historic fabric, and works that affect its character can require listed building consent from the local authority. Chasing original plaster, lifting historic floorboards or altering panelling may all be sensitive.

Practical considerations include:

Planning cable routes that minimise damage to historic plaster, joinery and floors, sometimes using existing voids, skirting or surface containment instead of chasing.
Checking whether listed building consent is required before starting, as carrying out unauthorised works to a listed building is a serious matter.
Using electricians experienced with period properties, who understand both BS 7671 and the need to protect historic fabric.

None of this changes the electrical standards the work must meet — BS 7671 and Part P apply just as they do to a modern home — but it shapes how the rewire is carried out. Confirm any consents with your local authority's conservation team before committing.

Planning the work and living through it

Beyond cost and consents, a rewire in an old house benefits from careful planning, because the disruption is greater and the opportunities to get things right are not easily repeated once walls are made good again.

A few points are worth settling before work starts:

Sequence with other trades: if the property is being renovated, the rewire should come before plastering and decorating, since chasing walls and lifting floors damages fresh finishes. Coordinating the electrician with plasterers and joiners avoids tearing into completed work.
Add what you need now: with floors up and walls open, it is the most economical moment to add extra sockets, lighting points and provision for modern demand such as an electric shower or EV charging. Retro-fitting these later repeats the chasing and making good.
Heating and integrity: in a period home, decide how cable routes interact with original features so the finished installation is discreet and the historic fabric is preserved.
Whether to move out: a full rewire of an occupied old house is dusty and disruptive, with power off room by room. Many people move out for the most intensive first-fix days and return for second fix and making good.

At completion, the new installation is certified with an Electrical Installation Certificate (EIC) and, because a rewire is notifiable under Part P of the Building Regulations, registered with Building Control — usually automatically through the electrician's competent person scheme. Keep that certificate with the property's records: in an older home with a long history of alterations, clear documentation of the new wiring is genuinely valuable when you come to sell.

One disruption, done well: because reopening a period home's walls and floors is so disruptive, plan the rewire to capture everything you need in one go - extra sockets, lighting and future provision - rather than facing the same mess again later.

Frequently asked questions

Is rewiring an old house more expensive?

Usually yes. Solid walls with no cavity, lath-and-plaster ceilings and awkward floors make running cable slower, and the chasing and replastering add to the bill. The wiring itself is similar; the extra cost is mostly in access and making good.

Do I need consent to rewire a listed building?

Possibly. Listed building status protects the historic fabric, and works that affect its character can require listed building consent. Check with your local authority's conservation team before starting, and plan cable routes to minimise damage to historic plaster and joinery.

Does an old house always need a full rewire?

No. Age makes a rewire more likely, but the decision follows from an EICR. If the installation tests as fundamentally sound, targeted repairs and a consumer unit upgrade may be enough. A full rewire is recommended when cable has degraded throughout or many serious faults are found.

Sources & further reading

Figures on this page are typical UK ranges drawn from published sources and depend on your specific property. They are guidance, not a quotation. Legal duties are summarised for guidance — confirm the current position on GOV.UK.