5 Common Mistakes to Avoid in a Bathtub-to-Shower Conversion in Dover, NH
Converting a bathtub to a shower sounds simple on paper: remove the tub, set a shower base, run tile, and call it a day. In Dover homes, especially the pre-war capes and mid-century ranches that dot neighborhoods from Central Ave to Back River Road, the reality is more nuanced. Framing quirks, aging cast iron drains, and a tight footprint can turn a quick project into a headache if you miss key details. After seeing dozens of tub-to-shower conversions over the years, these are the five mistakes that most often sabotage timelines, budgets, and daily comfort.
Mistake 1: Ignoring the drain size and placement
A tub often drains with a 1.5-inch line. Most modern shower pans and local best practices call for a 2-inch drain to handle higher flow and reduce clogging. If you keep the old line, you may get away with it for a while, but hair and soap scum will win. I have opened up Dover basements after only a year of use to find slow-drain complaints traced to undersized pipe.
The placement matters just as much. Many older tubs drain near the end, whereas shower bases typically have a center or off-center drain. If you don’t reposition the trap to match the new base, you invite standing water or odd pitch in the floor. In multi-story homes along Silver Street, access from below is limited, so you might need to open a portion of the kitchen ceiling to reroute the drain properly. It is messy, but cheaper than dealing with persistent slope problems and funky odors.
Mistake 2: Skipping waterproofing behind the pretty surface
Tile and grout are not waterproof. They are a decorative shell over the actual water barrier. I have seen jobs bathtub replacement cost guide where installers put tile right over green board, and it looked fine for a year. Then winter hit, the outside walls cooled, and vapor started condensing behind the tile. By spring, the shampoo niche was a petri dish.
A good tub-to-shower conversion layers defenses: a solid backer (cement board or fiber cement), a continuous waterproof membrane across walls and niches, and a pan or base with an integrated upturn. If you choose a tiled floor over a prefab base, use a proper shower pan liner or bonded waterproof system with a compatible drain. Pay special attention to transitions, like where glass meets tile or where a bench intersects a wall. Those joints fail first. In Dover’s older homes with balloon framing, cavities can draw moisture upward like a chimney, spreading damage beyond the bath. A belt-and-suspenders approach saves you from mold remediation later.
Mistake 3: Overlooking structural and leveling challenges
Bathtubs forgive uneven floors. Showers do not. A shower base demands a level, stable surface, and a mortar bed for a tiled shower pan requires precise slope: typically a quarter inch per foot toward the drain. The classic mistake is setting a base on a subfloor that is out by a quarter inch across six feet, then trying to shim the walls to make tile lines look straight. You end up with lippage and a door that does not seal.
In Dover, many subfloors are plank or older ply that has loosened over decades. Expect to remove the old underlayment, re-screw the subfloor to the joists, and correct out-of-level conditions with planing or self-leveler before the base goes in. A quick check with a 6-foot level during demo tells you what you are in for. If there is bounce, add blocking or sister joists near the drain to support the trap and prevent squeaks, especially in second-floor baths where movement telegraphs through the ceiling below.
Mistake 4: Choosing the wrong door or opening for the room
A shower that works on a showroom floor can crowd a real bathroom. Swing doors need clearance, and in many Dover bathrooms the toilet is inches away. A poorly chosen door can bang into a vanity or require you to contort just to get in. I once replaced a beautiful 28-inch swinging door with a bypass style because a client kept clipping the towel bar behind it. Small change, big usability win.
Think through sight lines and reach. If the shower head is on the far wall, you should be able to turn it on without getting soaked. If a knee wall will support glass, ensure there is solid blocking so the panel does not wobble. For tight spaces, a low-profile base with a sliding door or even a glass panel with a 22 to 24-inch walk-in opening often fits better than a hinged door. And for households planning to age in place, consider a curbless entry early, since that affects framing, waterproofing, and floor height transitions beyond the bath.
Mistake 5: Underestimating ventilation and seasonal moisture
Seacoast humidity plus hot showers equals condensation. A tub-to-shower conversion often increases daily shower frequency, which magnifies poor ventilation. Fans rated at 50 to 70 CFM are common in older baths, but a typical 5 by 8 shower room needs closer to 80 to 110 CFM with a short, straight duct run that terminates outdoors. Venting into an attic, still found in some older Dover homes, invites mold in the insulation and staining on the ceilings below.
Winter introduces another wrinkle. Exterior walls get cold, and that temperature difference drives vapor into cavities if the barrier is sloppy. Run the fan on a timer for at least 20 minutes post-shower. If you are redoing the ceiling, upgrade to a fan with a humidity sensor. A good painter’s finish on the ceiling, like a mildew-resistant acrylic, does not replace airflow, but it helps.
Budget, permits, and real Dover constraints
For a straightforward tub-to-shower conversion with a quality acrylic base, waterproof walls, glass, and modest plumbing reroute, homeowners in Dover typically invest in the mid four figures to low five figures, depending on finishes. Tiled pans, custom glass, and moving supply lines bump costs. The city’s permitting process for residential bathroom remodels is predictable, but inspectors will look closely at the drain upgrade, GFCI protection for outlets, and fan venting to the exterior. It is worth pulling permits, not only for safety but also for resale. Buyers and their inspectors in this market ask pointed questions about bath conversions.
Material lead times matter. Custom glass can take 2 to 4 weeks after measurement. Plan the sequence so you are not without a functional bath for longer than necessary. Many pros set the base, waterproof walls, and tile, then install a temporary curtain while waiting on glass.
Practical choices that pay off
A few upgrades consistently deliver value:
- A 2-inch drain with a removable hair trap, paired with a quality P-trap you can access through the ceiling below if needed.
- Solid-surface or high-density acrylic panels for clients who want minimal grout, especially in rentals near UNH commuter routes.
- A thermostatic mixing valve when multiple users share the bath, to avoid surprises when someone runs the dishwasher.
- Blocking in the walls for future grab bars, even if you do not install them today.
- A handheld shower on a slide bar, useful for rinsing the enclosure and for seated showering if mobility changes.
How to vet your installer
Not every contractor excels at wet spaces. Ask to see a recent Dover job, not just a portfolio from elsewhere. Inquire about the exact waterproofing system they use and how they treat niches and benches. Demand a clear scope: drain size change, subfloor repairs, membrane type, and glass style. The better proposals specify brand and model for the pan, valve, and fan, not just “builder grade.” A seasoned installer will also look at your home’s quirks, like the crawlspace under a South End ranch or the plaster-and-lath on a Garrison, and explain how they will handle them.
Final thoughts from the field
A tub-to-shower conversion can make a small Dover bathroom feel bigger and function better, but the craft is in the parts you do not see: the quiet fan that actually vents, the level base, the membrane tucked just right behind that sleek tile. Avoid the five mistakes above, and you will enjoy the daily routine without hidden surprises. Whether you are converting a bathtub to a shower for accessibility, easier cleaning, or simply because you never use the tub, a methodical plan and the right details will keep the project on schedule and the shower performing for years.
