The bathroom remodel mistakes that show up years later, and how to avoid them

Most failures hide behind the tile

The most common bathroom remodel mistakes are missing or poorly built waterproofing, an undersized or badly ducted exhaust fan, a layout built to code minimums instead of comfort, lighting the mirror from overhead and forgetting to add blocking in the walls while they are open. Waterproofing is the big one: it is the easiest thing to cut and the most common reason a bathroom has to be redone early. Get layout, waterproofing and ventilation right, and the tile, vanity and fittings become the enjoyable part.

Bathroom remodeling is one of the core services at Chateau Concepts, where I design the room and also run the construction. The mistakes below are the ones I see most often, both in my own planning reviews and in bathrooms I am asked to redo.

Mistake one: treating tile and grout as the waterproofing

Grout is porous, and tile is not a waterproof barrier. Water that gets past them has to be stopped by what is underneath, and in a failed shower that layer is usually missing, interrupted or built wrong. The damage happens out of sight, in the framing and subfloor, and often is not noticed until there is a stain on a ceiling below or a musty smell that will not go away. If you are already seeing those signs, read what a musty smell and a ceiling stain may mean before you plan the remodel.

A shower that lasts is built in layers, and each one matters. Ask your contractor to show you the membrane before any tile goes on, and photograph it. Also photograph the open walls before they are closed, so years from now you know exactly where the pipes, valves and blocking are. Waterproofing is the easiest line to trim when a budget gets tight, because nobody will ever see it, and that is exactly why it deserves a visit.

• Cement board or foam board in wet areas, not standard drywall; greenboard resists moisture but is not waterproof
• A continuous waterproof membrane, sheet or liquid-applied, with no gaps at seams and corners
• A shower pan sloped correctly to the drain
• Flexible sealant at movement joints such as inside corners, not rigid grout
• Waterproofed niches, with the shelf sloped slightly forward so water drains out

Mistake two: a fan that only makes noise

A bathroom fan has one job, which is to remove moist air before it soaks into paint, drywall and grout. Many fans are too small for the room, vent into the attic instead of outside or run through a long, crushed flexible duct that chokes the airflow. The result is peeling paint, mildew on the ceiling and a room that never quite dries.

On my website I suggest sizing the fan at roughly 1 CFM per square foot for bathrooms up to about 100 square feet, with a typical minimum of around 50 CFM; larger rooms, enclosed toilet compartments and steam showers may need more or a second unit. Duct it to the outside through short, smooth duct with few bends. Then put it on a timer or a humidity sensor, because nobody remembers to leave a fan running for twenty minutes after a shower.

Mistake three: designing to the code minimum

Building codes set the legal minimum, not the comfortable one. A toilet squeezed to the minimum distance from a vanity is legal and miserable. When I plan a bathroom, I design to the comfortable figure wherever the room allows, and only fall back to the minimum when space forces it. These are the pairs I publish on my website, code minimum first and comfortable second.

• Clear floor space in front of a fixture: 21 inches minimum, 30 inches comfortable
• Toilet centerline to a wall or fixture: 15 inches minimum, 18 inches comfortable
• Toilet compartment width: 30 inches minimum, 36 inches comfortable
• Shower interior: 30 by 30 inches minimum, 36 by 48 inches or larger comfortable
• Between two sink centerlines: 30 inches minimum, 36 inches comfortable

Mistake four: moving the toilet without checking the floor

Moving plumbing is the largest cost variable in a bathroom, and the toilet is the hardest fixture to move because it means opening the floor. How hard depends on the foundation. In many older Park Cities and Preston Hollow homes built on pier and beam, there is a crawl space underneath, and rerouting is comparatively straightforward. In houses on a slab, especially a post-tension slab common in North Dallas and newer construction, it means cutting concrete and working carefully around the tensioned cables, which is considerably more expensive.

Decide where the plumbing goes first, before you fall in love with a layout that needs it moved. If the walls are open anyway, it is also the moment to replace old galvanized supply lines. Some layout problems are better solved by borrowing a few feet from an adjacent closet or hallway than by relocating fixtures.

Mistake five: lighting the face from above

A single fixture centered over the mirror throws shadows under the eyes and chin, which is exactly what you do not want for shaving or makeup. Light the face from both sides of the mirror, with sconces near eye level or tall diffused fixtures, and add general lighting for the room and a dimmable low-level light for nighttime trips.

Coordinate the mirror and the lights with the faucet on the elevation drawing. Mirrors hung at one height, sconces at another and a faucet centered somewhere else is a mistake that only shows up once everything is installed, and it is surprisingly common. Drawing every wall of the bathroom as an elevation, with the mirror, sconces, faucet, outlets and towel bars all dimensioned, is how it gets caught before anyone drills a hole.

Mistake six: closing the walls without blocking

Blocking is solid wood framing added between studs so that heavy or frequently used items have something secure to attach to. It costs very little while the walls are open and a great deal once tile is up. The list of things that need it is longer than most people think.

Think ahead when you decide where it goes. A bathroom you remodel now may need to serve you, or a parent, for a long time, and grab bars are far easier to add later if the blocking is already in the wall. Planned well, a bathroom can be ready for aging in place without looking like a hospital room: a curbless shower, good lighting, comfortable clearances and blocking where a bar might one day go. Photograph the blocking before the walls are closed so you know where it is.

• Grab bars, including ones you may only want years from now
• Towel bars, robe hooks and toilet paper holders
• Wall-hung vanities and toilets
• Heavy mirrors and medicine cabinets
• Frameless glass door hinges, which carry real weight

The smaller mistakes that still sting

Some errors will not cause water damage but will annoy you every day. Each one is easy to prevent on paper and expensive to fix later.

• A shower niche on an exterior wall, where it weakens insulation or will not fit between studs
• Underestimating the weight and swing of a frameless glass door
• Fittings from different product lines whose finishes do not quite match
• No outlet where you need one, such as inside a drawer for a hair dryer
• A rain head plus body sprays specified without checking the water pressure
• Polished stone or large glossy tile on the floor, which can be slippery when wet
• Large-format tile laid on an uneven old floor without budgeting for leveling

Getting the order of decisions right

Most of these mistakes come from making decisions in the wrong order. The sequence I use is layout first, then plumbing locations, then the vanity and storage, then tile and surfaces, then lighting, and finally fittings and hardware. Start with what you need to store, then design the vanity around it; drawers generally serve better than a single cabinet with a drain trap in the middle. Choose grout color from a wet sample board, because dry grout looks different.

Respect the waits that cannot be compressed. Waterproofing and tile setting both need curing time, and frameless shower glass is measured only after the tile is finished. In the ranges I publish, a full primary bath takes four to eight weeks on site; my guide on how long a remodel really takes explains where the rest of the time goes. If you are working with your own contractor, several of these items fall into the gaps described in hiring a designer for the plans only, so assign them by name.

How I plan and build a bathroom

My process has four steps. At the consultation I assess whether the plumbing can move and what that would cost given your foundation. Then I draw the plan and elevations, with fixture placement, clearances and every wall shown. Selections come next, with tile, stone, fittings, vanity, glass and lighting chosen together rather than one at a time. During the build, the waterproofing is inspected before tile goes on, curing times are respected and the finish trades are sequenced so nothing is rushed. Permits are confirmed with the right jurisdiction before scheduling, since requirements differ between Highland Park, University Park and the City of Dallas; in older houses there is more to know, which I cover in renovating an older Park Cities house.

If you are planning a bathroom, the first step is a consultation in your home, where I look at the room, talk through what you need from it and give you my first impressions on the spot.

Questions people ask me