Knob and tube wiring replacement cost is usually the first question San Francisco homeowners ask once an inspector, an insurer, or a real estate disclosure points out that a home still has this outdated system. It is a fair question, and it deserves a straight answer instead of a single number pulled out of context, because the real cost swings widely depending on the home, the building, and how much of the original wiring is still in place.
Why Replacement Costs More in San Francisco Than the National Average
National cost guides give a useful starting point. According to HomeGuide, replacing knob and tube wiring nationally runs between roughly 12,000 and 36,600 dollars, or about 10 to 20 dollars per square foot, depending on home size, the number of circuits, and how accessible the wiring is. Angi reports a similar national range and adds that the Bay Area’s Victorian and Edwardian homes tend to land on the higher end, since their multi-level, harder-to-access layouts make the work more labor-intensive than a single-story ranch home built with an easy attic and crawlspace.
San Francisco adds a few cost pressures of its own on top of that national range: higher local labor rates, a denser permitting process, and a housing stock where multi-unit buildings and narrow lot lines are the norm rather than the exception. A straightforward single-family home with attic and basement access will generally land toward the lower end of any quoted range. A multi-story Victorian with finished walls throughout, minimal attic access, and knob and tube wiring shared across more than one unit will land well above it.
What Actually Drives the Final Price
A few factors do most of the work in determining where a specific home falls within that range.
- Home size and circuit count. Every room adds wiring, outlets, switches, and fixtures, so a larger home with more rooms naturally costs more to rewire than a small cottage.
- Wiring accessibility. A home with an open attic and basement is far less disruptive to rewire than one with plaster walls, no attic, and finished ceilings throughout, since the latter usually requires opening walls to fish new wiring through.
- Panel condition. Many homes with knob and tube wiring also have an outdated panel that was never sized for modern loads, which adds a panel upgrade to the scope of work.
- Number of units affected. In a duplex or small apartment building, the wiring is often shared or interconnected across units, which can require coordinating access and scheduling with more than one owner or tenant.
- Repair and finish work. Opening walls and ceilings to run new wiring means drywall, lath and plaster, or paint touch-up afterward, and that repair cost is separate from the electrical work itself.
Of these, accessibility tends to swing the price the most in San Francisco specifically. A ranch-style home in most parts of the country has a full attic and a basement or crawlspace, which gives an electrician a relatively open path to run new wiring without disturbing finished walls. Many San Francisco homes, especially the classic Victorians and Edwardians the city is known for, were built tall and narrow with finished plaster on every level and little to no true attic space. That difference alone can move a project from a moderate rewire into one that requires opening ceilings and walls throughout the home.
Building type matters just as much as building age. A single-family home is usually the simplest scenario, since one owner makes the decisions and the electrician has access to the entire structure. A flat inside a multi-unit building is more complicated, particularly if the knob and tube wiring for more than one unit shares a common chase or attic space. In that case, an electrician may need sign-off or scheduling coordination from a property manager or homeowners association before work can start, which can extend the timeline even when the electrical work itself is straightforward.
Typical Cost Ranges for a San Francisco Rewire
Here is roughly how project scope and cost tend to line up for a San Francisco home, based on the size and accessibility factors above.
These are planning ranges, not a quote. The only way to get an accurate number for a specific address is an on-site assessment, since two homes of the same square footage can have very different costs depending on how the walls and framing were built.
Permits and Inspections: What San Francisco Requires
Almost any knob and tube replacement beyond a like-for-like device swap requires an electrical permit in San Francisco. According to SF.gov, electrical permits are issued through the Department of Building Inspection, and the wiring must be inspected before it is covered by drywall or ceiling material. A licensed contractor typically pulls the permit and schedules the required inspections as part of the project, so this is generally built into a contractor’s quote rather than something a homeowner has to arrange separately.
Permit and inspection fees are a real, if usually modest, part of the total project cost, and they exist for a good reason: an inspector confirms the new wiring meets current code before it disappears behind a wall for another eighty years. Skipping this step is not a shortcut worth taking. Unpermitted electrical work is one of the most common issues that surfaces during a home sale, and it can complicate both a future disclosure and a future insurance application in ways that cost far more to untangle than the permit fee itself would have.
Financing and Timing a Rewiring Project
Not every homeowner needs, or wants, to pay for a full rewire out of pocket all at once. Because knob and tube wiring is rarely an emergency in the way a dead panel or an active hazard would be, many homeowners plan the work in phases, starting with the areas an inspector or insurer specifically flagged and expanding from there as budget allows. The tradeoff is that phased work usually costs somewhat more in total than doing it all in one project, since each phase involves its own setup, and the areas already completed may need to be worked around later. Homeowners who know a full rewire is inevitable, whether because of an insurance requirement or a planned sale, generally save the most by scoping the entire project at once rather than spreading it across several smaller jobs.
Why the Electrical Panel Usually Needs Attention Too
It is common for a home with knob and tube wiring to also have a panel that has never been upgraded to match today’s electrical demand, things like central air, electric vehicle charging, or a kitchen full of high-draw appliances that simply did not exist when the panel was installed. Rewiring the home without addressing an undersized or outdated panel often just shifts the bottleneck rather than solving it, which is why most contractors will evaluate the panel as part of the same visit. Our electrical panel upgrade and rewiring service covers this combined assessment, so homeowners get one clear scope of work instead of separate, disconnected estimates for wiring and panel work.
“Homeowners are often budgeting for the wiring and forget the panel is part of the same problem. If the panel was sized for a 1930s house, it usually needs to be part of the conversation, not an afterthought.”
– Luis, High Voltage Electrical
Hidden Costs Homeowners Often Miss
The electrical work itself is only part of the total bill. A few costs that catch homeowners off guard include drywall or lath and plaster repair once the walls are opened, paint touch-up to match existing finishes, and in some cases temporary relocation if a large portion of the home needs to be opened at once. In an older San Francisco building with plaster walls, patch and repaint work can add a meaningful amount to the project, which is worth asking about upfront rather than discovering it once the wiring work is already underway.
It is also worth asking a contractor directly whether their quote includes finish repair or stops at the electrical work itself. Some rewiring quotes cover cutting and patching drywall as part of the scope, while others leave the finish work to a separate contractor entirely. Neither approach is wrong, but the difference can meaningfully change what the project actually costs from start to finish, so it is a fair question to ask before signing off on any estimate.
Partial Rewire vs. Whole-House Rewire: Which Costs Less Long-Term
A partial rewire, focused on a kitchen, a bathroom, or whichever area has the most active knob and tube wiring, will always cost less upfront than a whole-house rewire. The tradeoff is that it leaves the rest of the home’s original wiring in place, which means the same conversation about age, condition, and eventual replacement is likely to come up again down the road, whether that is triggered by an insurance renewal, a remodel, or a future sale. A whole-house rewire costs more at the time of the project, but it resolves the issue completely and tends to be the choice homeowners make when they are already planning to stay in the home for years, or when they know a sale is somewhere on the horizon.
How San Francisco Compares to the Rest of the Bay Area
Knob and tube wiring is not a San Francisco-only issue. Pasadena, Oakland, and plenty of other pre-1950 California cities are working through the same conversation with their own older housing stock. What sets San Francisco apart is the combination of an unusually old citywide housing stock with unusually high local labor and permitting costs, which tends to push San Francisco estimates toward the upper end of the ranges reported by national cost guides like HomeGuide and Angi rather than the middle. Homeowners comparing quotes from a general contractor versus a licensed electrical specialist sometimes see a meaningful cost difference here too, since a specialist is set up to move efficiently through exactly this kind of project rather than treating it as one line item within a larger renovation.
How Insurance and Resale Value Factor Into the Decision
Cost is not the only number that matters here. San Francisco’s insurance market has grown far less tolerant of knob and tube wiring, and the California FAIR Plan exists precisely for homeowners who cannot get standard coverage for reasons like this one. A completed rewire often restores access to standard market insurance, which can offset part of the project cost over time through lower premiums compared to a FAIR Plan policy paired with a supplemental policy. On the resale side, a documented, completed rewire is generally viewed as a straightforward improvement, while unresolved knob and tube wiring tends to become a negotiating point once a buyer’s inspector flags it.
Contractors sometimes see this play out in real time during a listing. A seller who rewires ahead of putting a home on the market usually avoids a repair credit negotiation altogether, while a seller who lists first and rewires after an inspection often ends up paying a premium for rush scheduling on top of the original project cost. Building the rewiring cost into an early renovation budget, rather than treating it as a last-minute fix once a buyer’s inspector raises it, tends to be the more cost-effective path either way.
Every one of the ranges in this guide is a starting point for a conversation, not a final number, and that is by design. Two San Francisco homes built the same year on the same block can have completely different rewiring costs depending on how they were originally framed and what previous owners already changed. If you are trying to scope a knob and tube wiring project for your San Francisco home, the most reliable next step is an on-site evaluation rather than guessing from a national average. You can learn more about our work across the city on our San Francisco electrician services page, or start with a full electrical safety inspection to get an accurate picture of what your home actually needs before committing to a scope of work.
