Our 1950s Scarborough bungalow has the original bathroom — what surprises should we expect during a gut reno?

A 1950s Scarborough bungalow with its original bathroom will almost certainly reveal several hidden conditions once demolition begins — the most common being cast iron drain pipes, galvanized steel water supply lines, damaged subfloor around the toilet and tub, and outdated electrical wiring. Budget an additional 10 to 20% beyond your renovation quote as a contingency for these discoveries.

Scarborough's post-war bungalow stock — built rapidly through the late 1940s and 1950s across neighbourhoods like Birch Cliff, Cliffcrest, Wexford, and Agincourt — represents some of the most common bathroom renovation projects in the GTA. These homes are now 70 to 75+ years old, and a bathroom that has never been renovated will have materials and systems that are well past their expected lifespan.

Plumbing Surprises

Cast iron drain stacks and branch drains are virtually guaranteed in a 1950s bungalow. Cast iron has a lifespan of 50 to 75 years, and at 70+ years old, your drain pipes may show significant internal corrosion, pitting, or even cracks. Your plumber will assess the condition once exposed — if the cast iron is still solid, it can stay. If it is corroded, flaking, or cracked, replacement with ABS plastic is recommended, which adds $1,500 to $3,500 depending on how much of the stack needs to be replaced.

Galvanized steel supply lines are the other near-certainty. These pipes corrode from the inside over decades, restricting water flow and eventually developing pinhole leaks. If your bathroom currently has low water pressure, this is likely why. Replacing galvanized supply lines with copper or PEX during the renovation is strongly recommended — it is far cheaper to do while the walls are already open than as a standalone project later. Expect $1,000 to $2,500 for supply line replacement in the bathroom area.

Some 1950s homes also have lead solder joints on copper pipes or, in rare cases, lead supply lines. Your plumber should identify these during rough-in and recommend replacement.

Subfloor and Structural Issues

Subfloor damage around the toilet flange is found in the majority of original 1950s bathrooms. Seventy years of micro-leaks around the wax ring seal, condensation, and occasional overflow have almost certainly caused some degree of rot in the plywood or board sheathing subfloor. Expect your contractor to find soft spots, discoloured wood, or outright rot that requires cutting out and replacing sections of subfloor — typically $500 to $1,500 in additional work.

Floor joists should be inspected at the same time. Water damage that has penetrated through the subfloor may have affected the tops of the joists, particularly around the toilet and along the tub edge. Sistering damaged joists (bolting new lumber alongside the weakened joist) is a straightforward structural repair that adds $300 to $800.

Electrical and Ventilation

Original 1950s electrical in Scarborough bungalows is typically 60-amp service with ungrounded two-prong outlets and possibly knob-and-tube wiring in some areas. Your bathroom renovation will require GFCI-protected outlets, a dedicated circuit for the exhaust fan, and potentially a circuit for heated floors — all of which require permits and ESA inspection. If any knob-and-tube wiring is found in the bathroom walls during demolition, it must be replaced. Budget $800 to $2,000 for bathroom electrical upgrades depending on the existing conditions.

The original exhaust ventilation in many 1950s bungalows is either non-existent (the bathroom had a window and no fan) or a small, inadequate fan vented into the attic rather than to the exterior. The Ontario Building Code now requires mechanical exhaust ventilation in every bathroom, vented directly to the outside. Adding proper ducting to the roof or exterior wall is a standard part of the renovation.

What This Means for Your Budget

For a complete gut renovation of a 1950s Scarborough bungalow bathroom, plan for a base renovation cost of $20,000 to $35,000 depending on your material selections, plus a $4,000 to $8,000 contingency for the hidden conditions described above. A good GTA contractor will include a contingency allowance in their quote and will communicate clearly as each discovery is made, with costs approved before additional work proceeds.