# Plaster Wall Rewiring in Boston > Rewiring a house with plaster walls near Boston: routes planned through attics and basements, small fishing holes, lead-safe rules and a separate patching line. URL: https://deckerbostonknobandtube.com/plaster-wall-rewiring/ [Decker Boston Knob and Tube](https://deckerbostonknobandtube.com/) arranges rewiring for plaster-walled houses across Boston, Cambridge, Somerville and nearby cities, carried out by licensed and insured electricians. Each new circuit still has to get from the panel to its outlet, but in a plaster-and-lath house it travels through finished walls that crack when cut carelessly and cost real money to restore. So the access plan matters as much as the wiring. It decides how much plaster gets opened, who closes it, and whether the state’s lead-safe rules come into play. No public figure says how many Boston-area houses keep their original plaster, so treat age as a reason to plan for it, not proof. Census figures put 46.7% of Boston’s housing units before 1940. ## What happens on the first visit For a plaster house, the first visit maps routes as carefully as it maps circuits, because the routes set the patching bill. ### Circuits first, then the ways through The electrician starts at the panel and traces every circuit, then surveys the house for paths. Is the attic walkable or floored, and how deep is any insulation? Is the basement ceiling open, finished or dropped? Do closets stack from floor to floor, and is there an old chase beside the chimney or the plumbing stack? Each answer moves cable away from finished walls. Attic and crawl space access is one of the biggest drivers of the price. ### The walls themselves Before cutting, the existing cracks, loose patches and historic trim are noted, such as cornices, ceiling medallions and picture rails. That keeps the patching scope tied to the wall as it really was, and steers routes around finishes that are hard to match. The [knob and tube inspection](https://deckerbostonknobandtube.com/knob-and-tube-inspection/) page covers the circuit side of the same visit. ## Plaster versus drywall Drywall is a sheet screwed to studs. Cut a hole and you patch it with a piece of the same sheet. Plaster on wood lath is a different material, and it changes every cut. ### How plaster holds on Plaster was troweled wet onto narrow wood strips with gaps between them. It squeezed through the gaps and hardened into keys that lock it to the lath. Cut it with a vibrating or dull blade and the keys around the opening break, so a neat hole grows a crack or a loose, sagging patch. That’s why cutting technique, a sharp blade and support around the opening matter more here than in a drywall house. ### What it changes on the job | | Drywall house | Plaster-and-lath house | | --- | --- | --- | | Cutting an opening | Clean, quick, predictable | Brittle; the surrounding keys have to be protected | | Fishing inside the cavity | A clear bay between studs | Lath edges and plaster blobs snag the fish tape | | Patching | A drywall piece and joint compound | Fill to the lath, then layers built up to match the wall’s thickness | | Matching the finish | Usually flat paint | Smooth hard finish, sometimes cornices or textured coats | | Dust and paint | Gypsum dust | Plaster and lath dust, and lead in older paint layers | ## Getting cable through without opening walls Most of the route runs through spaces that already exist. The Massachusetts text of section 334.17 allows cable to be fished between access points in finished buildings where strapping it to framing is impracticable, and that clause is the legal footing for a rewire that keeps the plaster. ### Vertical paths Top-floor circuits drop from the attic through the top plate into a wall bay; first-floor circuits come up from the basement through the bottom plate. Where a house is balloon framed, the stud bays can run open from sill to attic, though fire blocking added later can stop them partway. Stacked closets and old chases carry runs between floors without touching a finished room. ### Horizontal paths Running across a wall is harder than running up it. The usual answers are lifting a baseboard and running cable behind it, going down to the basement and back up, or following the gap behind ceiling strapping, which the state code treats as support when cable runs diagonally behind strips of about three-quarters of an inch and isn’t pulled taut. ### Where a cut is the better trade Where a header, a fire block or a floored attic stops the fish tape, a small access cut at that one point usually beats forcing the fish tape and cracking the wall. Homeowners report that electricians who can fish a replacement without leaving large, jagged holes can be hard to find, so ask each bidder for the route plan. The [quote comparison guide](https://deckerbostonknobandtube.com/guide/comparing-knob-and-tube-rewiring-quotes/) lists what to check. Ask for the route plan, not only the price Two quotes for the same plaster house can open very different amounts of wall. The plan shows which. Get an Estimate (617) 405-3599 ## When more of the wall has to open Fishing has limits, and the honest plan says where they are rather than promising no openings. ### Blocked cavities and taller buildings Cavities packed with old insulation, framing changes from past remodels, and long horizontal runs can all make a short opening the faster and cleaner choice. Above three stories, NM cable circuits generally have to stay on the floor or unit they serve, which calls for other wiring methods in the taller masonry rowhouses covered on the [Back Bay, Beacon Hill and South End page](https://deckerbostonknobandtube.com/service-areas/back-bay-beacon-hill-south-end/). In a [triple-decker](https://deckerbostonknobandtube.com/triple-decker-rewiring/), each floor is usually routed as its own unit. ### Using a remodel If a kitchen or bath is being opened anyway, that’s the moment to run new circuits through open framing, and to follow old runs out of the remodeled rooms while access is easy. The [remodel rewiring page](https://deckerbostonknobandtube.com/knob-and-tube-remodel-rewiring/) covers the sequence with a general contractor. ## Openings, inspection and restoration Every access cut is a future patch. The restoration plan belongs in the quote as its own line, not folded into the electrical price. ### Inspection before anything closes Under Rule 10 of 527 CMR 12.00, the inspector of wires has up to 72 hours after notice, not counting weekends and holidays, to see new wiring, and nothing may cover it before then. Openings stay open until then, so patching is scheduled after the rough-in inspection, never before. ### Who patches, and to what finish There are three common arrangements: the electrical contractor closes the openings, you hire a plasterer, or you patch before painting yourself. Whichever you choose, the quote should state the finish, whether rough-filled, ready for paint or painted. Where there is decorative plaster, a plasterer is often the better fit for that part. ### Lead paint and historic finishes In a house built before 1978, the Department of Labor Standards treats disturbing more than six square feet of painted surface per room, without lead testing, as renovation work for a licensed lead-safe renovation contractor. Small fishing holes can stay under that line; strips of opened wall usually can’t. The [asbestos and lead paint guide](https://deckerbostonknobandtube.com/guide/asbestos-and-lead-paint-during-rewiring/) covers both. Boston’s historic district commissions review exterior work, not interior wiring, so the inside concern is protecting original plaster and trim; the [historic district guide](https://deckerbostonknobandtube.com/guide/rewiring-a-house-in-a-boston-historic-district/) explains what is reviewed. ## What a plaster rewire costs Plaster raises the price mainly through access and restoration, not the electrical work. A [whole house rewire](https://deckerbostonknobandtube.com/whole-house-rewiring/) of the active circuits falls in a typical Boston-area budgeting range of $8,000 to $25,000 or more, and plaster-heavy jobs can run well past it. Patching is usually priced separately and depends on the number of openings, the finish, lead-safe practice and any historic trim. The [Boston cost guide](https://deckerbostonknobandtube.com/guide/knob-and-tube-replacement-cost-boston/) breaks a price into its parts, the [cost estimator](https://deckerbostonknobandtube.com/tools/knob-and-tube-cost-estimator/) gives a range without a phone call, and the [living at home guide](https://deckerbostonknobandtube.com/guide/living-at-home-during-rewiring/) covers dust and the practical side. ## What's included - Circuit tracing plus a route survey of the attic, basement, crawl spaces, closets and chases - A route plan for each new circuit showing where cable is fished and where an access cut is needed - A record of existing plaster cracks and historic trim before any cutting starts - New cable fished through existing cavities, behind baseboards and along ceiling strapping where it allows - Access cuts kept to boxes, plates and blocked bays, sized to the obstruction - Openings left open for the rough-in inspection, then released for patching - A separate patching line that names who closes each opening and to what finish - Lead-safe practice flagged in the scope wherever openings in a pre-1978 house would pass the state threshold ## Fish through access holes, open selected walls or rewire during a remodel | | Fish through access holes | Open selected walls | Rewire during a remodel | | --- | --- | --- | --- | | Fits a house where | Plaster is sound and attic, basement or closet paths exist | Cavities are blocked, or a run has no fishable path | Walls or ceilings are coming down anyway | | How cable travels | Through existing bays, behind baseboards and along strapping | In longer openings along the run | Stapled to open framing | | Plaster disturbed | Small cuts at boxes, plates and obstructions | Strips of wall or ceiling along the route | Whatever the remodel removes | | Lead-safe rules in a pre-1978 home | Can stay under 6 sq ft per room | More likely to pass the threshold | Usually apply to the remodel already | | Main tradeoff | Slower routing, least restoration | Faster routing, more patching | Cheapest wiring, but only for the remodeled rooms | ## Related resources Learn Does knob and tube wiring have asbestos? Three old-house materials can sit right where a rewire goes: the wire's own covering, the paint on the plaster, and the fill in the attic. Here is what is known, what has to be tested, and how each changes the job. Learn What changes when you rewire a historic home in Boston? District commissions care about what the street can see, so most of a rewire never reaches them. The parts that do are the meter, the mast and the conduit, and inside, the plaster and trim are yours to protect. Decision Guide How do you compare knob and tube rewiring quotes? Two rewiring quotes for the same Boston-area house can be thousands apart and both be honest, because they describe different jobs. Lining them up on the same points shows which job each one is. Learn Can you live in a house while rewiring? Most households stay put through a knob and tube rewire. What makes that comfortable is planning the shutdowns, the dust and the heat before the first circuit goes dark. Cost Guide How much does knob and tube replacement cost in Boston? The range Boston-area owners budget with, the handful of things that push a house toward either end, and the public figures sitting inside every price. ## How a knob and tube job runs from first call to sign-off 1. First call Tell us what prompted the call, the town and type of building, how many units it has, and any deadline from an insurer, a sale or an insulation contractor. Photos, an inspection report or a Mass Save assessment help route the job to the right licensed electrician. 2. Assessment The electrician reviews the panel and the accessible attic and basement wiring, traces circuits, and notes which knob and tube is active, abandoned or mixed. You receive written findings and a scope, with access, patching and permit items listed separately. 3. The work The licensed contractor files the permit, then works area by area so the rest of the house keeps power. New cable is fished or run through open framing, the rough-in is inspected before walls close, and old circuits are disconnected and removed where reachable. 4. Completion Circuits are tested and labeled at the panel, the final inspection closes the permit, and you get the records: what was replaced, what was abandoned in place, and any knob and tube that remains. Those papers answer insurers, buyers and Mass Save. ## What this work looks like Plaster hallway with a drop cloth and a small access opening near the baseboard Patched and primed square of plaster around a new outlet above the baseboard Before After Plan the routes before anyone cuts plaster A route survey shows where cable can travel inside the walls you have, and where an opening is the better trade. Get an Estimate (617) 405-3599 ## Plaster Wall Rewiring questions ### How large are the openings when cable is fished through plaster walls? Most are at the places a box goes anyway, such as a new outlet or switch, and at obstructions such as a top plate, a header or a fire block, sized to reach that obstruction and no more. The number matters more than the size. The route plan in the quote should show where each one falls, so you can compare it with other proposals. ### Should the electrician patch the plaster, or should I hire a plasterer? Either works, as long as the quote says which. One workable split is for the electrical contractor to rough-fill the openings and a plasterer to finish them, which suits rooms with decorative work. Whoever does it, patching waits until the inspector of wires has seen the new wiring, and the finish level, whether filled, ready to paint or painted, should be written down. ### Can plaster ceilings on wood strapping be rewired from the attic? Often, yes. Where a ceiling was plastered over wood furring strips, the gap between strips gives cable a path, and section 334.30 of the state code counts cable laid at an angle behind nominal 3/4-inch strapping as supported, so long as it is left slack. Access from a walkable attic or a floor above makes top-floor ceiling lights among the easier circuits to replace. ### Do small access holes in plaster trigger Massachusetts lead-safe renovation rules? Not by themselves. In a pre-1978 home, the state's lead rules treat disturbing six square feet or less of painted surface per room as minor work. Count everything in the room, though: every cut, and any scraping or sanding around the edges during patching. Past that line, without lead testing, the work becomes renovation work for a licensed lead-safe renovation contractor. ### What does it cost to rewire a house with plaster walls? Plaster mainly raises the cost through access and restoration. Rewiring the active circuits in a whole house falls in a typical Boston-area budgeting range of $8,000 to $25,000 or more, and plaster-heavy jobs can run well past it. Patching is usually priced separately, driven by the number of openings, the finish level, lead-safe practice and any historic trim. ## Related services ### Whole-House Rewiring → Every branch circuit replaced with new grounded cable, for houses where knob and tube, cloth cable and old splices are mixed through the walls. ### Rewiring During a Remodel → Knob and tube found or planned for during a kitchen, bath or attic renovation, replaced while the walls are open and sequenced with the rest of the trades. ### Triple-Deckers and Multi-Family → Knob and tube replaced across occupied apartments, shared stairs and basements in three-deckers, two-families, condos, brownstones and rowhouses.