First, which bathroom this article is about: many older homes in Greater Boston have one small full bathroom of about 5×7 feet — a tub, a toilet, and a small sink lined up along one wall. This article is about that kind of full bathroom, with a tub or shower — not a powder room with only a toilet and a sink. The hard part of remodeling one is not picking tile. It is the old construction you cannot see inside the walls, the pipes, and the wiring — the standard approach for a newer house often runs into trouble at the very first step. Check the six things below before you start, and the layout and budget decisions that follow will have something solid to stand on. For the complete process of a full bathroom remodel, see this guide: https://blog.bathdesignboston.com/complete-guide-to-full-bathroom-remodels-in-boston-for-older-homes/ — this article covers only the old construction to check before work begins.
1. Walls: can the plaster and lath stay?
Interior walls in older homes are often wood lath covered with plaster. Before any demolition, check three things: whether the plaster is still firmly bonded to the lath, whether there are signs of moisture or mold, and whether the wall in the shower area is flat. Waterproofing in a shower has to sit on a sound substrate; if the substrate is already moisture-damaged or loose, the default recommendation is to replace it with board suited to wet areas and then waterproof, rather than tiling directly over old plaster. You cannot see the whole wall until it is opened, so this item needs a second look after demolition before the final call.
2. Water supply: pressure and rust from galvanized pipes
Homes built before the middle of the last century usually have galvanized steel supply pipes. After decades of use they scale and corrode inside, and the usual signs are low water pressure, slow hot water, and water that runs rusty. If a remodel replaces only the fixtures and not the pipes, the new faucets will soon clog with rust debris again. Judge by the pressure and the water, together with the age of the pipes, to decide how much to replace; how much actually gets replaced is decided on site once the walls are open — it is not something to promise on paper.
3. Drainage: cast iron pipes, and the trap size when a tub becomes a shower
The main drain stack in an older home is usually cast iron. It is durable in itself, but the joints and horizontal branches corrode and narrow over time. When a tub is converted to a shower, the Massachusetts plumbing code, 248 CMR 10.00, requires the trap for a shower stall to be no less than 2 inches (10.08(2)(b) Table 1), while a tub’s is 1½ inches — so the old tub’s drainage fittings cannot simply be reused and have to be redone during construction. The shower mixing valve must be a thermostatic or pressure-balancing valve Product-accepted by the Massachusetts Board of State Examiners of Plumbers and Gas Fitters, with the outlet temperature limited to 120°F (10.10(4)(c)). This is why converting a tub to a shower in an older home is never just about what is above the floor.
4. Electrical: old wiring and GFCI protection
The circuit in an older bathroom often also serves the lighting, and outlets with no ground-fault protection are common. Under current requirements, bathroom receptacle circuits need GFCI protection; we covered the specifics in our article Bathroom GFCI Requirements in Massachusetts: https://blog.bathdesignboston.com/massachusetts-bathroom-gfci-requirements/ . If you find knob-and-tube wiring, do not bury it under insulation — how to deal with wiring that old has to be assessed on site by a licensed electrician, and this article draws no specific conclusion about it.
5. Ventilation: small bathrooms trap moisture
The smaller the room, the more concentrated the moisture. The common problems in older bathrooms are no exhaust fan at all, or a fan that vents into the ceiling cavity instead of outdoors. We covered fan selection and vent runs in Bathroom Ventilation in Older Boston Homes: A Practical Guide: https://blog.bathdesignboston.com/bathroom-ventilation-older-boston-homes/ , so this article will not repeat it — just one reminder: venting to the outside during the remodel is far easier than fixing it afterward.
6. Homes built before 1978: check for lead paint before any demolition
Massachusetts has two layers of rules for homes built before 1978. The first is the lead paint law: when a child under 6 lives in the home, the owner has a legal responsibility to have lead paint hazards inspected and addressed. The second is the lead-safe renovation rule (454 CMR 22.00): paid renovation work in this kind of housing must be done by a company holding a Massachusetts lead-safe renovation contractor license, and each project must have a certified lead-safe renovator supervisor designated for it. Housing for the elderly or persons with disabilities, and dwellings with no bedrooms, are not covered — except that elderly or disabled housing where a child under 6 lives, or is expected to live, still counts. Whether bathroom work that disturbs old walls and old tile falls under this rule depends on the scope of the work, so check this step first when scheduling and leave time for it. For other old materials from the same era (such as asbestos), the same advice applies: have a licensed third party assess them before demolition, then decide how to proceed.
A word on layout for a small bathroom
Only after the six construction questions are settled does layout come up: in a small bathroom, keep the shower and toilet where they are if at all possible — moving them means rerouting the drainage, which is the most expensive change in an older home — and then work out storage and sink size. If you are adding just a half bathroom instead, see this guide: https://blog.bathdesignboston.com/powder-room-remodel-boston-complete-guide-for-greater-boston-homeowners/ ; and for whether a tub-to-shower conversion needs a permit, see: https://blog.bathdesignboston.com/tub-to-shower-conversion-boston-permit/ .
To close: the right order for remodeling a small bathroom in an older home is check the construction first, decide the layout second, and choose materials last. A budget and schedule fixed before the construction is checked will mostly have to be redone once the walls are open. If you are not sure which situation your bathroom falls into, start with a free on-site estimate — we look at the house first, then give you a formal quote.