The 7 Biggest Bathroom Renovation Mistakes (and how to avoid them)

A bathroom renovation is an investment that needs to last you the next 15 to 20 years. Yet many projects go wrong, resulting in leaks, moisture problems, or a bathroom that already looks dated within a few years. After carrying out hundreds of bathroom renovations, we at Refresh Bathrooms keep seeing the same mistakes come up time and again. The good news? They’re all preventable.

In this guide, we walk through the seven most common mistakes and show you exactly how to avoid them. Whether you’re tackling it yourself or hiring a professional, this knowledge will save you time, money, and headaches.

Mistake 1: Unrealistic budget and no buffer for unexpected costs

The biggest bathroom renovation mistake of all? Assuming your renovation will come in exactly on budget. Many people work with a tight budget of, say, €5,000, only to discover that hidden pipe damage, extra tiling, or a missing component pushes the total to €7,500.

Why does this happen? Old bathrooms often hide surprises behind the tiles: outdated pipes clogged with limescale, rotting wooden joists from leaks, or unexpected drainage issues. It’s only when you start demolishing that you find out what actually needs doing. On top of that, costs like rubble disposal, extra materials for measurement errors, or delivery delays are often forgotten.

Want to know exactly what a new bathroom costs? Our cost guide gives you a complete overview of all possible expenses.

How do you prevent it?

Set aside a 15–20% contingency buffer on top of your estimated costs. On a €10,000 budget, that means €1,500–€2,000 extra to absorb unexpected expenses.
Request a detailed quote that lists every item: materials, labour, disposal costs, and potential additional work. Companies that only give you a rough figure without a breakdown? That’s where the biggest risk lies.
Have your pipework inspected in advance if your bathroom is more than 20 years old. This prevents nasty surprises halfway through the project.
Opt for all-inclusive concepts like our bathroom renovation service, where you know exactly what you’ll pay upfront — including materials, labour, and completion.

Refresh approach: We work with transparent all-in prices. After the initial consultation, you receive one clear price for the complete renovation, with no hidden extras. What we agree on is what you pay.

Mistake 2: Poor ventilation or no ventilation at all

One of the most underestimated bathroom renovation mistakes: inadequate ventilation. The result? Mould on the grout, damp patches on the ceiling, smelly towels, and a musty odour that just won’t go away. Worse still, moisture seeps into other rooms and can cause structural damage to your home.

Why does this happen? Many people think a small window or a basic extractor fan is enough. It isn’t. Every shower releases an enormous amount of moisture — up to 2 litres of water can evaporate into the air. Without proper extraction, that moisture lingers, condenses on cold surfaces, and gives mould free rein.

In Belgium, for instance, mechanical ventilation in the bathroom is a legal requirement! Yet it’s regularly overlooked or deliberately skipped to cut costs. You’ll find more tips on keeping your bathroom clean and fresh in our comprehensive guide.

How do you prevent it?

Install a modern mechanical extractor fan with humidity sensing that switches on automatically when the air gets too moist. This doesn’t have to be expensive and works far more effectively than manual ventilation.
Make sure it has sufficient capacity: the fan should be able to extract at least 50 m³ per hour for a standard bathroom of 6–8 m².
Position the fan correctly: as far from the door as possible and ideally above or beside the shower, so moist air is extracted directly.
Choose materials that resist moisture: wall panels without grout lines prevent moisture from settling between tiles and causing mould growth.

Mistake 3: Wrong materials for a wet environment

Beautiful wooden cladding, plasterboard on the walls, or regular paint instead of bathroom paint. It looks great in the showroom, but it’s a disaster once you actually start showering. Materials that can’t handle constant moisture deteriorate in no time.

Why does this happen? People underestimate just how extreme the conditions inside a bathroom are. We’re talking about:

Daily temperature swings of 15–40 degrees
Humidity peaking at 80–90% during a shower
Direct contact with water, soap, and cleaning products
No or limited natural ventilation

Ordinary materials can’t cope with this. Wood rots, plasterboard becomes sponge-like, and cheap grout discolours within months.

How do you prevent it?

Choose 100% waterproof materials in wet zones. Think glazed tiles, mineral marble, or high-quality wall panels specifically developed for bathrooms.
Pay attention to sealant and grout: always use sanitary sealant with anti-mould properties and high-quality cement grout that can withstand moisture.
Avoid porous materials such as untreated wood, regular plaster, or standard MDF near washbasins — unless they’ve been specifically made water-resistant.
Go for grout-free solutions: tiles have grout lines where moisture, dirt, and mould accumulate. Modern wall panels are a great alternative to tiles. They are 100% waterproof and have no grout lines.

According to insurer Interpolis, the use of incorrect materials is one of the most common causes of water damage after renovations — with all the consequences that brings for your insurance.

Refresh approach: We exclusively use high-quality, waterproof wall panels. They require minimal maintenance, have no grout lines where mould can grow, and last at least 20 years without discolouration.

Mistake 4: Underestimating plumbing and pipework

It sounds so simple: just take off the old tap and put the new one on. Until you discover that the pipes don’t line up, the water pressure is too low, or a leak suddenly floods the entire ground floor. Plumbing isn’t a detail — it’s the foundation everything else depends on.

Why does this happen? People focus on what they can see: beautiful tiles, a sleek washbasin, a luxury rain shower. But behind the walls is where the real work happens: water supply, drainage, pressure, temperature control. If this isn’t right, you’ll have problems within months.

Common issues according to experts:

Pipes that aren’t properly soldered — leads to leaks after weeks or months
Hot and cold water pipes too close together — causes heat loss
Pipes without proper bracketing — creates vibrations and wear
Drains without proper venting — results in odour problems and emptying traps
Old pipes with limescale build-up — restricts water pressure and will soon start leaking

How do you prevent it?

Always hire a certified plumber for pipework, even if you’re doing everything else yourself. This is not the place to cut costs.
Replace old pipes during renovation if your home is more than 30 years old or you’re seeing a lot of limescale. The investment prevents more expensive problems later.
Test everything before finishing: leave all pipes under pressure and check for leaks before closing up walls.
Check water pressure and temperature throughout your entire home before ordering that luxury rain shower — otherwise it’ll be a disappointing trickle.

Refresh approach: All our plumbing work is carried out by certified professionals. We routinely check your existing pipes and advise whether replacement is necessary. All installations are thoroughly tested before handover.

Mistake 5: A layout that’s too cramped with no room to move

The dream: a freestanding bath, a walk-in shower, a double washbasin, and a toilet. All in a 6 m² bathroom. The result: you bang into things every morning, the shower door can’t open fully, and the toilet is so tight your knees press against the wall. An overstuffed bathroom isn’t luxury — it’s a daily frustration.

Why does this happen? People see stunning bathrooms online and want everything they see there. But they forget that those example bathrooms are often 12–15 m², while their own bathroom is only 5–7 m². Every element needs space to move around, and that space simply isn’t always available.

Research shows that an impractical layout caused by too few circulation routes is one of the most common bathroom renovation mistakes. Want to know more about smart layouts? Read our guide on the best layouts for small bathrooms.

Minimum space requirements:

Toilet: at least 60 cm wide, 80 cm depth for knee clearance
Washbasin: at least 70 cm wide, 100 cm of clear space in front
Shower: at least 80 x 80 cm; comfortable is 90 x 90 cm or larger
Freestanding bath: at least 170 x 75 cm, plus space around it to step in
Circulation route: at least 60 cm of clear passage

How do you prevent it?

Make choices: in a small bathroom, you can’t have everything. Do you really need that bath, or would a spacious walk-in shower where you can move comfortably be much better?
Draw everything to scale: use graph paper or an online bathroom planner. Measure everything including the swing arcs of doors and drawers.
Think about hidden storage: floating furniture, built-in cabinets, niches in the wall. This way you keep storage out of the circulation routes.
Account for tolerances: shower enclosures can vary by 2–3 cm in width, and ceramics can shift after production. Always factor in a little margin.
Seek professional advice: an experienced bathroom specialist can see at a glance what will and won’t fit, and can suggest smart solutions.

Refresh approach: During our free consultation, we take all measurements and work out a smart layout together. We give honest advice if something won’t fit or will be impractical, and always come up with an alternative that actually works.

Mistake 6: Wrong order of works

You’ve just laid beautiful new tiles. The next day the plumber arrives to re-route pipes and has to break straight through your new tilework. Or you install an expensive washbasin, only to find that the tiles behind it can’t be finished neatly afterwards. The wrong sequence of work can delay your project by weeks and cost hundreds of euros extra.

Why does this happen? A bathroom renovation brings many different trades together: demolition, plumbing, electrical, tiling, plastering, painting. If this isn’t planned properly, people end up waiting for each other, work has to be redone, or you end up with a messy end result.

Want a complete overview? See our ultimate bathroom renovation checklist with all the steps laid out.

The correct order:

Demolition and disposal — completely remove old bathroom
Plumbing rough-in — re-route pipes, test water pressure
Electrical rough-in — run cables for lighting, ventilation, heating
Floor levelling — ensure a level surface and proper drainage falls
Waterproof base layer — primer, vapour barrier where needed
Wall and floor cladding — tiles, wall panels, or plasterwork
Plumbing finishing — connect sanitary ware, fit taps
Electrical finishing — install lighting, extractor fan, switches
Finishing and styling — sealant, furniture, accessories
Final clean and handover

How do you prevent it?

Create a detailed schedule with all steps and who is coming when. Share this with all parties involved.
Order materials in good time: tiles, sanitary ware, and furniture often have 2–6 week lead times. Make sure everything is on site before you start.
Appoint a single main contractor to handle coordination — this prevents miscommunication between different tradespeople.
Choose systems that are sequence-independent: our bathroom renovation without breaking work, using wall panels over existing tiles, saves a great deal of demolition and repair work.

Refresh approach: We handle the entire planning and coordination. Because we have everything in-house with our own build teams, your bathroom renovation runs like clockwork. No waiting times, no miscommunication — just fast, neat results.

Mistake 7: Not thinking about future needs

You’re 35 and step in and out of the bath without a second thought. But your bathroom will last 20 years. Will you still be that agile then? Will your 70-year-old father be able to shower safely when he comes to stay? This question is often never asked — until it’s too late.

Why does this happen? Nobody likes thinking about getting older or physical limitations. But a bathroom that’s perfect now can become unusable in 10–15 years if your mobility decreases. A high bath rim becomes an obstacle, slippery tiles a fall risk, and a narrow doorway impossible to navigate with a walking frame.

Want to know more about future-proof living? Read our guide on a safe bathroom for seniors or on how to prepare your home for the future.

Future-proof choices:

Walk-in shower instead of a bath or shower tray: no threshold means no trip hazard, even with reduced mobility
Anti-slip flooring in the shower: smooth tiles are dangerous, especially when wet
Anchor points for grab rails: even if you don’t install them now, make sure the structure is solid enough to mount handles later
Wide doorway: at least 80 cm, preferably 90 cm for wheelchair or walking-frame access
Wall-hung toilet: adjustable in height if that ever becomes necessary, and space underneath for cleaning or mobility aids
Good lighting: adequate light prevents tripping and falling

How do you prevent it?

Think 20 years ahead: how old will you be then? Do your parents live nearby and visit often?
Go for threshold-free solutions: many local authorities offer subsidies for future-proof adaptations
Choose neutral, timeless colours: white, beige, and light grey always look good and suit any interior
Invest in quality: cheap materials need replacing after 8–10 years; quality lasts 20–30 years

Refresh approach: Our walk-in showers are standard threshold-free and future-proof. We think ahead about future needs and advise on smart adaptations you can make now — without extra cost or compromising on design.

Avoid these bathroom renovation mistakes with professional guidance

The seven bathroom renovation mistakes we’ve discussed are all preventable. The common thread? Good preparation, quality over short-term savings, and working with experts who know what they’re doing. A bathroom renovation doesn’t have to be a stressful project full of surprises and setbacks. With the right approach, realistic planning, professional advice, and a focus on quality, you create a bathroom you’ll enjoy for 20 years.

What makes Refresh Bathrooms different?

All-in transparent pricing — no hidden costs or surprises afterwards
Fast execution — complete bathroom renovation in 2–3 days, walk-in shower in 1 day
Minimal breaking work — wall panels over existing tiles means less mess and disruption
Single point of contact — from intake to handover, no communication through intermediaries
Own tradespeople — everything under one roof, no hassle with subcontractors

Request a free consultation

Want to avoid these bathroom renovation mistakes in your own renovation? Schedule a free home consultation. We’ll go through everything together, answer your questions, and give honest advice on what is and isn’t possible. No obligations — just good information to help you make a smart decision.

Plan Free Consultation

Frequently Asked Questions

What is the biggest mistake in a bathroom renovation? The biggest mistake is a too-tight budget with no buffer for unexpected costs. Always reserve 15–20% extra for surprises such as old pipes that need replacing or additional materials.
How do I prevent mould in my new bathroom? Ensure good mechanical ventilation (legally required in Belgium), use waterproof materials, and ideally choose wall panels without grout lines where mould can take hold. Dry surfaces after showering.
Do I always need to replace my old pipes? Not always, but you should if your home is more than 30 years old or you’re seeing a lot of limescale. A plumber can carry out an inspection. Replacing pipes during a renovation prevents more expensive problems later.
How much space do I need at minimum for a comfortable shower? At least 80 x 80 cm, but 90 x 90 cm or larger is much more comfortable. Don’t forget to keep at least 60 cm of clear circulation route for freedom of movement.
Can I save money by doing it myself? Yes, but not on critical elements like plumbing, electrical work, and waterproofing. Mistakes here will ultimately cost more than you save. Tiling or painting can be done yourself if you’re handy.
How long does an average bathroom renovation take? Traditionally 3–4 weeks. At Refresh Bathrooms, thanks to our smart wall panel system and efficient planning: complete bathroom in 2–3 days, walk-in shower only in 1 day. Read more about how a bathroom renovation in 1 day works.