Designing and Remodeling Older Bathrooms: Behind the Finishes


On many occasions we’ve heard the following or similar sentiments expressed by a homeowner after consulting on a bathroom renovation in an older home in the Washington, DC area: “But my bathroom is only eight feet by five feet. How in the world can such a small space possibly cost thirty thousand dollars to remodel? That’s crazy!” And yes, it is crazy but it’s also true. Renovating older homes (when work is performed up to current building codes) is far more expensive than remodeling in new construction.


In newer homes, the infrastructure of a room (plumbing, wiring, framing, subfloor) is typically sound, and only the finishes need replacing. This is never the case in older homes, particularly in bathrooms. Significant “behind the scenes” work is required just to bring the guts of the room up to date and code. There are four major infrastructure areas that must be addressed in your standard older bathroom remodel:


Up until the late 1960’s, most bathroom floors were constructed with a “mud-set” mortar bed. Floor joists were not installed to be level, and subfloor was not used. Instead, “nailers” and a platform were put in place towards the bottom of each joist bay. Plumbing pipes were then run through the joists, and a wet mortar mix packed around the pipes and into the joist bays. The mortar mix was built up to a level plane (an inch or two above the highest joist), onto which the floor tile was set. So your bathroom floor is literally an eight to ten inch solid pad of mortar that extends down into each joist bay with the plumbing pipes embedded inside. This entire floor needs to be jack-hammered out (literally) to expose the old plumbing and the floor joists. The floor then needs to be framed level (by “sistering” new lumber to the existing joists), subfloor installed, and then concrete backer-board fastened to the subfloor onto which the new tile can be set.


Beginning early in the 20th century, galvanized piping became the go-to material for plumbing in bathrooms and kitchens. Galvanized has since been replaced by copper and PVC, since it has a shelf life of about 70 years – rusting, and eventual leaking is simply inevitable. Therefore, before replacing any finishes in the bathroom, the old galvanized pipes must be removed and replaced with copper feeds and PVC waste lines. But as outlined above, this is no easy task as the original plumbing pipes are literally buried in a thick mortar slab. The temptation (in the interest of cost and time savings) is to perform a “pull and replace” renovation, where new fixtures are quickly attached to existing plumbing lines. While perhaps a viable short-term solution, this approach is flawed as the plumbing will eventually leak: it’s not a question of “if”, but rather, “when”.


Lath and plaster was used to cover the framing at interior walls up until the 1950’s when it was replaced by drywall. This involved attaching thin wooden lathes (horizontally) to the vertical framing members, and then covering the lathes with plaster. Because the framing lumber and lathes were typically not of uniform size, several coats of plaster were needed to obtain a smooth and (somewhat) level surface. At the beginning of your bathroom renovation, all the lathe and plaster must be removed from the walls and ceiling which is a dirty and time-consuming process. Once the original structure is exposed, the bathroom walls and ceiling need to be made level and plumb by “sistering” new lumber to each of the existing framing members. This reframing process is often more labor intensive than it would be to simply frame a new space.


Electrical Wiring:
Current building codes stipulate that bathrooms require a Ground Fault Interrupted (GFI) outlet that is run off a dedicated circuit. In bygone eras, this was not the case, so it is often necessary to pull new wiring from the main electrical panel. New designs often call for upgrades to lighting, or new fixtures such as Jacuzzi tubs and heated towel warmers which require additional circuits to be run from the main panel. Even if no new circuits are necessary the existing wiring is likely obsolete, possibly a fire hazard, and certainly out of compliance with modern building codes. It is essential that all the old wiring is stripped from the bathroom, and replaced with code compliant materials. In short, the entire bathroom will need to be rewired.

When considering these significant infrastructural upgrades that are necessary to remodel an older bathroom correctly, it makes sense how even a small space becomes so costly. And there is never a shortage of companies that are eager to cut these steps out (or minimize the importance of them) in order to cut costs (often in half). And while such a company may produce a finished product that looks fantastic initially, it is all for naught when the plumbing starts to leak. At this point, the only option is to gut the bathroom to the joists, redo the plumbing, and start the finish work all over again.

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