How to plan a bathroom remodel

Layout and the clearances that matter

Bathrooms fail on inches. These figures come from the National Kitchen & Bath Association's planning guidelines and from model building codes; codes set the legal minimum, and the guidelines describe what is actually comfortable. Where they differ, build to the guideline.

Three layout principles worth more than any finish decision:

• Do not put the toilet in the sight line from the door. It costs nothing at the planning stage and it is the difference between a bathroom that feels considered and one that does not.
• Give the shower the window, or give it the best wall. Whichever the room allows — the shower is where you actually spend time.
• Check door swings against everything. The entry door against the vanity, the shower door against the toilet, the linen closet against the towel bar. This is the most common small failure in a finished bathroom.

If the room is genuinely too small for what you want, the honest answer is often to borrow space from an adjacent closet or hallway rather than to squeeze. That is a layout question, and it belongs on a drawn plan before it becomes a demolition question.

The plumbing question, answered first

The largest single variable in a bathroom budget is whether the fixtures stay where they are. Keeping the toilet, shower and sink in place keeps the project comparatively contained. Moving them — particularly the toilet, which needs a drain of a specific size and slope — means opening the floor, and the cost depends entirely on what is under it.

In Dallas, this splits fairly cleanly by construction type. A house on a pier-and-beam foundation, common in older Park Cities and Preston Hollow homes, has a crawl space, and rerouting drains is comparatively straightforward. A house on a post-tension slab — standard in much of North Dallas and in newer construction — requires cutting concrete, which is disruptive, dusty and requires care to avoid the tensioning cables. Confirm which you have before you plan a layout that moves the toilet.

Also worth establishing early: the age and material of the supply lines. Galvanized steel piping, still present in some pre-war homes, corrodes internally and restricts flow. If it is there, the moment the wall is open is the moment to replace it.

Waterproofing: the work you will never see

This is the part of a bathroom that decides whether you are doing this again in eight years. It is also the part that is easiest to cut, because once the tile is on, nobody can tell.

• Cement board or foam board, never standard drywall in a wet area. Greenboard is moisture-resistant, not waterproof, and does not belong in a shower.
• A continuous waterproof membrane over the substrate — either a sheet membrane or a liquid-applied one. This is the actual barrier. Tile and grout are not waterproof; grout is porous by nature.
• A properly built shower pan with the correct slope to the drain, and a pre-slope beneath the pan liner where a traditional mud bed is used.
• Movement joints where tile meets a different plane — corners, wall-to-floor transitions — filled with flexible sealant rather than rigid grout, which cracks.
• A niche built into the framing, waterproofed as part of the assembly, with its shelf sloped very slightly forward to drain.

Ask to see the waterproofing before tile goes over it, and photograph it. Any competent contractor expects this request. It is also worth photographing every open wall before it is closed, so that in five years you know where the studs, blocking and pipes are.

Ventilation

Dallas humidity plus a hot shower plus an undersized fan equals peeling paint, mildew in the grout and eventually damage inside the wall. Get this right and it costs very little.

• Size it to the room. A common rule of thumb is roughly 1 CFM per square foot of floor area for bathrooms up to about 100 square feet, with a typical minimum around 50 CFM. Larger bathrooms, or those with a separate enclosed toilet or a steam shower, need more — and often a second unit.
• Duct it outside. Not into the attic, which simply relocates the moisture problem into your roof structure.
• Use rigid or smooth duct where you can, kept short and with as few bends as possible. Long runs of crushed flexible duct throttle a fan to a fraction of its rating.
• Put it on a timer or humidity sensor. The fan needs to run well after the shower ends, and nobody remembers to do that manually.

Tile, stone and grout

A few decisions here have outsized consequences:

Floor tile needs slip resistance. Look for a coefficient of friction appropriate to a wet area — polished stone and large glossy porcelain are beautiful and treacherous underfoot. Smaller tiles on a shower floor also help, because the extra grout lines add grip and accommodate the slope to the drain.

Natural stone in a shower is a commitment. Marble is lovely and will etch and require periodic sealing. Porcelain that convincingly imitates marble has improved enormously and is genuinely maintenance-free. This is a preference, not a right answer — just make it knowingly.

Grout color changes everything. Matching grout to tile makes a surface read as one plane; contrasting grout emphasizes the pattern and the geometry. Both are valid; they are entirely different rooms. Look at a sample board of your actual tile with your actual grout, wet, before committing.

Large-format tile needs a flat substrate. The bigger the tile, the less tolerance for a wall or floor that is out of plane. Budget for floor levelling if the house is old.

Vanity, storage and lighting

Storage is where bathrooms most often disappoint, because it is planned last. Work out first what actually needs to live in the room — daily products, towels, cleaning supplies, hairdryer, medicines — then design the storage for that list. Drawers are more useful than a cabinet with a single shelf and a plumbing trap in the middle of it. A custom vanity is worth considering whenever the room's dimensions do not match a stock size, which in older homes is most of the time.

Lighting deserves the same three-layer treatment as a kitchen, with one bathroom-specific rule: light the face from both sides, not from above. A single overhead fixture casts shadows straight down onto the face, which is unhelpful for shaving and worse for makeup. Sconces flanking the mirror at roughly eye level, or a well-diffused vertical fixture on each side, solve it. Add a separate, dimmable low-level light if the bathroom is used at night.

Mistakes that are expensive to undo

1. No blocking in the walls. Add solid blocking behind grab-bar locations, towel bars, the vanity and any wall-hung fixture while the walls are open. Even if you never fit a grab bar, the option costs almost nothing now and is disruptive later.
2. The mirror and the light fixture fighting the plumbing. Sconce heights and mirror sizes have to be coordinated with the faucet centerline on the elevation, not improvised on site.
3. A shower niche placed on an exterior wall in a way that compromises insulation, or landing between studs where it will not fit.
4. Underestimating the door. A frameless glass shower door has real weight and needs correct hinge support and clearance to swing.
5. Choosing fittings from separate ranges and discovering the finishes do not match. “Brushed nickel” varies noticeably between manufacturers.
6. No outlet where you actually need it. Inside a drawer or cabinet for the hairdryer and toothbrush keeps the counter clear.
7. Ignoring water pressure before specifying a rain head plus body sprays. Check available flow first.

Jan Revels

ASID Allied Professional Interior Designer · Chateau Concepts, Dallas

Jan has practiced interior design in Dallas since 1997 and founded Chateau Concepts in 2001. She holds a BFA in Interior Design from the University of North Texas. She designs and general-contracts residential and commercial projects across the Park Cities, Preston Hollow and North Dallas. Read her full profile →

Written and reviewed by Jan Revels before publication