Bathroom renovation in an old wooden house: what affects the price

Why a timber floor structure costs more than a panel floor

A panel flat has a flat, level concrete slab that takes tiling and waterproofing with minimal preparation. A wooden house has joists, often uneven after decades of settling, sometimes sagging under the point where a bath or a cast-iron tub once stood. Levelling that floor before anything else can go down is its own job, and it takes hours a panel flat never needs.

In many pre-war houses the joists themselves need attention: sistering a weakened joist, adding blocking, or replacing a section that has taken on damp. This is structural carpentry, not finishing work, and it has to happen before tiling, so it sits early in the schedule and early in the invoice.

None of this is visible until the old floor covering comes up, which is one reason a fixed quote for a wooden-house bathroom is usually given after someone has actually opened the floor, not from photos alone.

Waterproofing that an old house usually never had

Panel-flat bathrooms built from the 1970s onwards generally have some form of waterproof membrane under the tiles, even if it needs renewing. A pre-war wooden house often has none at all — the original bathroom, if it existed, relied on the floor covering itself and good luck. Any renovation now has to build that layer from scratch.

On a timber substrate this means a flexible waterproofing membrane or liquid-applied system that can move slightly with the wood without cracking, taken well up the walls and carefully sealed around every pipe penetration and the floor drain if there is one. Skipping this or doing it thinly is how water ends up in the joists within a few years, which is a far more expensive repair than doing it properly the first time.

This step alone can add a meaningful share of the labour hours compared with a concrete-floor bathroom, because there is more surface to treat and more junctions — between floor and wall, floor and pipe, old timber and new board — that all need attention.

Plumbing that often has to be redone from scratch

Original pipework in these houses is frequently undersized, corroded, or routed in a way that made sense for a single tap and makes no sense for a modern shower and washbasin. It is common to find that the supply and waste runs need replacing entirely rather than tying new fittings into old pipe.

Rerouting pipes through timber joists also means cutting notches or drilling holes in the right place, sized correctly, so the structural strength of the joist is not compromised — again, work that a concrete-floored flat does not require in the same way. Our plumbing work is billed from 45 € per hour, and in a wooden house this line item is usually larger than in a comparable panel flat simply because there is more to open up and more to replace.

If a drain needs to be relocated or a stack extended, that can also mean coordination with what sits below or beside the bathroom, which takes more planning time even before any pipe is cut.

What moves the final price range the most

For a full bathroom renovation in a wooden house, project costs typically start from around 3500 € and can run well beyond that depending on the condition found once work begins. The single biggest swing factor is the state of the floor structure — a house that has been reasonably maintained needs far less carpentry than one where damp has clearly been sitting under the old covering for years.

Access matters too: a ground-floor bathroom in a detached house is usually easier to work in than one on an upper floor with a narrow stairwell, where materials and old debris both have to be carried by hand. The scope of the plumbing rework, whether the layout changes or stays where it was, and whether the customer supplies fittings or we source them, all move the total as well.

• Condition of the joists once the old floor is opened
• Whether waterproofing needs building from nothing or just renewing
• How much of the existing pipework can stay versus be replaced
• Access to the bathroom — floor level, stairwell width, distance to carry materials
• Whether the layout changes, which usually means moving drains
• Who supplies materials — ours carry a 10 % handling fee, or you buy them

What you can check yourself before asking for a quote

A few honest observations before you contact anyone help a quote land closer to the final invoice. Press gently on the floor near the bath or shower tray — noticeable give or a spongy feel usually means the joists underneath have taken damp. Look at the underside of the floor from a cellar or crawl space if you have access, since staining or soft wood there tells you a lot before anyone lifts a board.

Note the age and material of visible pipework — old galvanised steel or lead is a different job from copper or plastic — and take photos of the whole room including corners and any existing damp marks on walls or ceiling below. None of this replaces an on-site look, but it means the first visit is spent confirming rather than discovering the basics from zero.

If the bathroom itself is sound and it is really the flooring or a specific fixture that needs attention rather than a full renovation, it is worth saying so — flooring work is quoted from 15 € per job and a smaller scope can be handled without opening up the whole room.