Plaster-To-Drywall Conversion in London, ON | Modernizing Older Walls & Ceilings
London Drywall provides plaster-to-drywall conversion for older residential walls and ceilings, backed by over 20 years of experience replacing deteriorated or impractical plaster assemblies with modern gypsum construction. Existing systems may contain wood lath with mechanically bonded plaster keys or later gypsum-lath bases, so conversion begins by identifying the substrate, overall wall thickness and framing behind it before plaster removal, furring or new gypsum board is specified.
Older plaster assemblies can conceal framing planes that are considerably less uniform than those expected for modern sheet materials. Once lath and plaster are removed, studs or ceiling members may require selective furring or other plane corrections so rigid 4-foot-wide gypsum panels have continuous, aligned attachment surfaces. Conversion planning also accounts for the depth formerly occupied by the plaster system, because changing that dimension can affect electrical-box projection, baseboards, window and door jambs, casing returns and other components originally fitted to the thicker wall.
Plaster-to-drywall conversion is available for older homes throughout London and surrounding communities including Woodstock, Innerkip, Beachville, Sweaburg, Norwich, Otterville, Burgessville, Tavistock, Drumbo, Princeton, Hickson and Bright. The service is particularly applicable to established housing across London and neighbouring Oxford County communities where traditional lath-and-plaster construction may remain behind decades of paint, wallpaper and previous alterations; each conversion is planned around the actual substrate and framing uncovered rather than treating an older plaster wall as equivalent to newly framed construction.
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✓ 20+ Years of Drywall Experience
✓ Installation, Repair, Ceiling Repair & Finishing
✓ Plaster-to-Drywall Conversions & Renovation Specialists
✓ Residential, Commercial & Rental Property Drywall
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We'll contact you within 24 hours to discuss your drywall project, assess any repair, renovation, or installation requirements, recommend the most suitable drywall solution, and provide a clear, no-obligation estimate for your home or commercial property.
Evaluating Existing Lath & Plaster Construction
Identifying Wood Lath & Plaster
Traditional wood-lath walls use narrow timber strips fastened horizontally across studs, with gaps between strips allowing the wet base coat to push through and form plaster keys behind the lath. Once those keys fracture, sections of plaster can become detached even when the painted face remains relatively intact. Inspection therefore considers hollow or loose areas, exposed lath and failed keys to determine how much of the original assembly must be removed during conversion.
Distinguishing Gypsum Lath Systems
Not every older plaster wall contains wood strips. Mid-century construction may use gypsum lath—often called rock lath—as a manufactured plaster base installed in sheets before finish coats were applied. Identifying gypsum lath matters because its demolition behaviour, fasteners and overall assembly thickness differ from wood lath, affecting removal quantities and how readily the underlying studs or ceiling framing can be exposed for the new gypsum-board system.
Measuring Existing Wall Thickness
Traditional plaster assemblies do not necessarily correspond to modern 1/2-inch (12.7 mm) drywall dimensions. Wood lath itself is commonly around 1/4 inch (6.4 mm) thick before multiple plaster coats are added, while actual finished thickness varies between homes and even between rooms. Measurements at receptacles, door openings or exposed edges establish the existing surface plane before demolition, providing a reference for later furring and transition work.
Assessing Framing Behind Older Plaster
Studs hidden behind rigid lath-and-plaster construction may be bowed, twisted, inconsistently spaced or positioned outside the plane required for large gypsum sheets. Once sufficiently exposed, framing can be checked with a straightedge or laser to identify high and low members before conversion proceeds. This is particularly important because the original plasterer could compensate for irregularities through variable plaster thickness, whereas modern gypsum board follows the framing plane much more directly.
Converting Older Surfaces To Gypsum Board
1. Removing Plaster & Lath To The Framing
A full conversion can remove the plaster layers and underlying wood or gypsum lath until the original studs or ceiling members are exposed. This eliminates the weight and variable thickness of the old assembly while providing direct access to the structure that will support the replacement panels. Demolition is performed in controlled sections because traditional plaster is dense and brittle, and pulling large areas away at once can disturb adjacent surfaces intended to remain.
2. Establishing A Flat Framing Plane
After demolition, the exposed framing is checked for crowns, recesses and members that no longer align with neighbouring studs or joists. Wood furring strips or appropriately selected shims can bring low areas forward to establish a consistent attachment plane rather than forcing rigid gypsum board across irregular framing. A laser or long straightedge helps identify deviations across multiple members before panels conceal the underlying geometry.
2. Accounting For Concealed Services
Removing an older wall surface can expose electrical wiring, plumbing, blocking and previous alterations that were inaccessible behind the plaster. These components must be considered before furring or gypsum panels are attached so screws are not driven blindly into concealed services. Older electrical boxes also require attention because their original depth was established for the former plaster surface and may no longer align with the face of the replacement wall.
2. Selecting Replacement Board Thickness
The new gypsum thickness is chosen according to the intended assembly rather than simply matching the depth of the removed plaster. Standard 1/2-inch (12.7 mm) gypsum board is common for many residential wall applications, while the remaining difference in surface position can be managed through the framing or furring strategy. Separating board selection from plane adjustment allows the new wall to use an appropriate modern panel while still coordinating with fixed features around the converted surface.
Managing Trim, Openings & Wall-Thickness Changes
- Extending Window & Door Jambs
Removing lath and plaster can shift the finished wall plane relative to existing window and door jambs. If the replacement gypsum surface finishes shallower than the original plaster, the jamb may project beyond the wall; if furring moves the surface outward, the jamb can become recessed. Jamb extensions or other accurately sized transition pieces can restore a flush relationship before casing is reinstalled, avoiding visible steps around older openings.
- Resetting Electrical Box Depths
Switch and receptacle boxes installed for a thicker plaster assembly may sit too far forward or behind the new gypsum face after conversion. The Ontario Electrical Safety Code requires boxes and associated components to remain properly installed and accessible, so wall-depth changes must be coordinated with electrical work rather than concealed behind trim or compound. Appropriate box extensions or repositioning by the applicable trade can bring devices into alignment with the reconstructed surface.
- Reworking Baseboard & Casing Transitions
Original baseboards, door casing and window trim were fitted to the dimensions of the plaster wall they bordered. A change of even several millimetres can alter mitres, reveals and the way casing meets jambs or adjoining walls. Recording trim locations before demolition and establishing the final gypsum plane before reinstalling millwork allows reusable pieces to be evaluated individually instead of assuming every original profile will automatically fit the converted assembly.
- Transitioning Into Remaining Plaster
Partial conversions sometimes terminate where an adjoining plaster wall or ceiling remains in service, creating two surfaces with different construction and potentially different thicknesses. Furring and gypsum thickness can be planned so the new face approaches the established plaster plane without an abrupt ridge or recessed edge. These junctions require particular attention at inside corners, doorway returns and intersecting walls because the conversion must accommodate the dimensional difference without unnecessarily removing sound neighbouring plaster.
Plaster-To-Drywall Conversion FAQs
How much heavier is traditional plaster than modern drywall?
Traditional lath-and-plaster assemblies can weigh substantially more than a single layer of gypsum board, but the exact difference depends on plaster thickness, number of coats and lath type. For comparison, 1/2-inch (12.7 mm) gypsum board commonly weighs roughly 1.5–2 lb per sq. ft., depending on the product. Because historic plaster thickness varies considerably, the existing assembly should be measured rather than assigning a standard demolition weight to an older London home.
Should old plaster be tested for asbestos before demolition?
Potentially. Older plaster systems themselves are not automatically asbestos-containing, but asbestos was historically used in some plaster compounds, textured coatings, joint materials and other building products. Ontario Regulation 278/05 governs asbestos on construction projects and defines asbestos-containing material as material containing 0.5% or more asbestos by dry weight. Suspect materials should be assessed before disruptive demolition rather than identified by appearance alone.
Can drywall be installed directly over existing plaster instead of removing it?
In some circumstances, but overlaying is different from a true plaster-to-drywall conversion. Adding gypsum board over existing plaster increases the finished wall thickness and can change relationships at receptacles, window jambs, door jambs, baseboards and casing. It also leaves the original lath-and-plaster assembly concealed underneath, so removal to framing is preferable when access to the substrate or complete replacement of the old system is part of the project objective.
Why can removing plaster affect a home's insulation or air sealing?
Older exterior walls may rely on several interconnected layers for air, vapour and thermal control, and demolition can expose gaps around framing, penetrations or previously inaccessible cavities. Ontario's modern construction requirements are different from those under which many older London homes were built, so opening the wall creates an opportunity to identify existing conditions. Any insulation, air-barrier or vapour-control work should be planned as part of the applicable building assembly rather than assuming the removed plaster performed no building-envelope function.
What should be checked before removing plaster from an older wall or ceiling?
The assembly should be investigated for concealed electrical services, plumbing, structural conditions and potentially hazardous materials before extensive demolition begins. In older buildings, lead-containing coatings and asbestos-containing materials may require assessment depending on the age and composition of the finishes. Determining these conditions beforehand helps establish whether ordinary plaster removal can proceed or specialized testing, abatement or another qualified trade is required first.
Planning to replace deteriorated plaster with modern gypsum walls or ceilings? Request a London plaster-to-drywall conversion quote using the form below.
Speak With a London Drywall Specialist
✓ 20+ Years of Drywall Experience
✓ Installation, Repair, Ceiling Repair & Finishing
✓ Plaster-to-Drywall Conversions & Renovation Specialists
✓ Residential, Commercial & Rental Property Drywall
✓ Serving London's Heritage Homes & Modern Renovations
We'll contact you within 24 hours to discuss your drywall project, assess any repair, renovation, or installation requirements, recommend the most suitable drywall solution, and provide a clear, no-obligation estimate for your home or commercial property.