Do I Need a Permit to Convert a Bathtub to a Walk-In Shower? in Nederland
Converting a bathtub to a walk-in (curbless or low-threshold) shower is one of the most popular aging-in-place and bathroom modernization projects. In most jurisdictions, it requires a plumbing permit because the conversion involves relocating or resizing the drain from a bathtub drain (typically 1.5-inch with an overflow) to a shower drain (2-inch minimum per code, often with a linear drain body), modifying the water supply rough-in for a new valve position, and changing the waterproofing membrane (the shower pan liner or sheet membrane system must meet code requirements that differ from a bathtub surround). An electrical permit is also required if the project adds or relocates a GFCI-protected outlet, exhaust fan, or recessed lighting in the wet area. The conversion frequently involves structural work — cutting into the subfloor to reposition the drain, adding blocking for grab bars, or modifying the curb — which triggers a building permit in addition to the plumbing permit.
Do you need a permit?
Sometimes
- Permitting authority
- Gemeente (Omgevingsloket)
- Typical fee
- €0–€300
What triggers a permit
- Relocating or resizing the drain from a 1.5-inch bathtub drain to a 2-inch shower drain
- Modifying the water supply rough-in (moving valve body, adding a thermostatic mixing valve or diverter)
- Cutting into the subfloor or floor joists to reroute the drain line to a new position
- Installing a new shower waterproofing system (pan liner, sheet membrane, or liquid-applied membrane)
Country-specific detail
In the Netherlands, converting a bad (bathtub) to an inloopdouche (walk-in shower) within an existing badkamer is generally classified as internal renovatiewerkzaamheden (renovation work) that does not require an omgevingsvergunning, provided the work does not alter the draagconstructie (load-bearing structure), the brandcompartimentering, or the afvoer-aansluiting op het riool (sewer connection point). However, the new afvoer must comply with NEN 3215 for drainage capacity, and the waterproofing must meet the manufacturer's garantie-eisen (warranty requirements) — most gemeenten recommend using an erkend installateur for the leidingwerk. If the conversion requires cutting into the betonnen vloer (concrete floor slab) to relocate the afvoer, a constructief advies (structural assessment) may be required by the gemeente, particularly in gestapelde bouw (apartments/flats) where cutting into the vloer affects the draagvermogen for the verdieping below.