Short answer: Usually not. Fitting a bathroom inside an existing house is internal work, which rarely needs planning permission. In Scotland the more important question is whether you need a building warrant. Refitting a bathroom in a one or two storey house usually does not, but extensions, structural changes, new drainage arrangements, and work in taller houses or many flats usually do.
People often use "planning permission" to mean any kind of council approval. In Scotland there are actually two separate systems, and a bathroom project is far more likely to involve the second one: the building warrant. Knowing which applies before you start saves delays, extra fees and problems when you come to sell.
This guide explains both, with a short note on how things differ in England. It is general guidance, not legal advice, and your council's building standards and planning teams have the final say on your project.
Planning permission and building warrants are not the same thing
| Planning permission | Building warrant | |
|---|---|---|
| Who deals with it | The council's planning service | The council's building standards service |
| What it looks at | How land and buildings are used and how they look, including the effect on neighbours and the street | Whether the work is safe and meets the building regulations, such as structure, drainage, ventilation and access |
| When a bathroom might need it | Extensions, external changes, listed buildings and some conservation areas | Structural work, extensions, changes to how wastewater is discharged, and work in taller houses and many flats |
You can need one, both or neither. A refit inside a bungalow usually needs neither. A new ground floor extension with a shower room usually needs both.
When you will not usually need a building warrant
Under the Scottish building regulations, work to or in a house does not need a warrant, provided it does not involve:
- increasing the floor area of the house
- demolishing or altering a roof, an external wall or an element of structure, such as forming a new doorway in a loadbearing wall
- underpinning
- work that adversely affects a separating wall shared with a neighbour
- changing the method of wastewater discharge
- any work in a house with a storey more than 4.5 metres above the ground, which normally means a house of three or more storeys
Some smaller items are also listed as not needing a warrant, including providing a single sanitary facility other than a WC (such as an extra shower or basin), installing an extractor fan, and fitting a stairlift in a home.
In practice, that means many common mobility jobs in a one or two storey house can go ahead without a warrant, for example:
- replacing an old bathroom suite in the same room
- taking out a bath and fitting a level access or walk-in shower
- adding grab rails, a raised toilet or a shower seat
- fitting a new extractor fan
Not needing a warrant does not mean anything goes. The work must still meet the building regulations, including drainage, ventilation and electrical safety.
When you are likely to need a building warrant
A warrant is generally needed if your bathroom project involves:
- An extension to create space for a new bathroom or shower room.
- Structural changes, such as knocking through a loadbearing wall to combine a bathroom and toilet, or forming a new doorway in one.
- New drainage arrangements, where the way wastewater leaves the house changes. If a new toilet cannot connect to the existing drains by gravity and needs a pumped system, ask building standards whether a warrant is needed.
- A house of three or more storeys. Here, even refitting a bathroom or forming an en-suite needs a warrant.
- A flat. Work in flats generally needs a warrant, particularly where it affects shared walls, floors or drainage.
Adding a brand new toilet is not covered by the minor work exemption for single sanitary facilities, so if you are creating a new WC, such as a downstairs toilet for someone who can no longer manage the stairs, check with building standards before you start. Our guide to the cost of putting a small mobility bathroom in a house explains how these extras affect the budget.
What if work has already started?
Starting work that needs a warrant without one is an offence in Scotland, and the council can take enforcement action. City of Edinburgh Council advises anyone in this position to stop and contact building standards. A late warrant application can be made before the work is finished, and once it is finished you can apply for a completion certificate for work done without a warrant. Both cost more, and you may have to open up finished work so it can be inspected. Unapproved work can also cause problems when you sell.
When planning permission might be needed
Planning permission is generally not needed for internal work. It can come into play when a bathroom project changes the outside of the building or its status. Examples include:
- Extensions. Some small extensions to houses can be built without a planning application, but the rules are detailed, so check before you design anything.
- External changes, such as new windows, or pipework and vents on the outside of the building, particularly on a front elevation.
- Listed buildings. Listed building consent covers internal changes as well as external ones, so even a new bathroom inside a listed house may need it.
- Conservation areas, where external changes are controlled more tightly.
- Flats, in some cases, particularly where external alterations are involved.
Flats and tenements
In a tenement or block of flats, check your title deeds and speak to your factor before you plan anything that affects shared parts of the building, such as the soil stack, common walls or floors. If you rent, you will need your landlord's consent. Council and housing association tenants usually have adaptations arranged by their landlord.
The rules that apply whether or not you need permission
Even a simple bathroom refit has to meet the building regulations. The main points are:
- Ventilation: a bathroom needs enough ventilation to prevent condensation and mould, usually an extractor fan.
- Drainage: waste pipes need the right falls and connections.
- Electrical safety: electrical work in Scotland should follow BS 7671. Look for SELECT or NICEIC registered electricians.
- Plumbing and gas: look for SNIPEF members or WaterSafe approved plumbers, and Gas Safe registered engineers for any gas work.
A good installer will handle this as part of the job. Our own team covers plumbing, electrics, joinery, flooring and waste removal, with no subcontractors, which keeps responsibility in one place. You can see the range of rooms we fit on our disabled bathrooms overview.
How it works in England
The principle is similar in England, but the names differ. Instead of a building warrant, building work needs building regulations approval through building control, and accessibility standards come from Approved Document M. Planning permission is, again, generally not needed for internal work, but extensions, listed buildings and external changes can need it. If you are reading English guidance online, remember that the Scottish rules and terms are different.
Planning an accessible bathroom: practical steps
If you are adding or adapting a bathroom for someone with reduced mobility, this order usually works best:
- Get an OT assessment through your council or Health and Social Care Partnership, so the design meets real needs.
- Talk to the council early if you hope to use the Scheme of Assistance, which gives a grant of at least 80% of the eligible cost for adaptations that give a disabled person access to a toilet, bath or shower. Do this before work starts.
- Agree the layout and check with building standards if it involves structure, drainage changes, a new WC, an extension or a flat.
- Choose an installer who understands mobility work and can explain what approvals your project needs.
Our guide on what to look for before a full bathroom remodel has a fuller planning checklist, and how long it takes to remodel a bathroom explains realistic timescales once any approvals are in place. Many of our mobility installations take as little as 3 days, and for a ground floor room, our disabled shower rooms are designed to fit around the person using them.
Planning a new or adapted bathroom? We will design it with you, flag anything that may need a building warrant, and provide a free 3D design and a no-obligation quote. Request your free design.
Frequently asked questions
Do I need a building warrant to replace my bathroom?
Usually not in a one or two storey house, as long as the work does not involve structural changes, an extension or a change to how wastewater is discharged. In a house of three or more storeys, or in many flats, a warrant is generally needed. Check with your council's building standards service if you are unsure.
Do I need permission to change a bath to a walk-in shower?
In most one or two storey houses, no. Swapping a bath for a level access or walk-in shower in the same room is normally internal work that needs neither planning permission nor a warrant, although it must still meet the building regulations.
Can I add a downstairs toilet without a building warrant?
Possibly, but check first. A new WC is not covered by the exemption for a single sanitary facility, and if the work involves structural changes or a new drainage arrangement, a warrant is likely to be needed.
Do I need permission to put a bathroom in a flat?
Planning permission is unlikely for internal work, but a building warrant is generally needed in flats. You should also check your title deeds and speak to your factor, and tenants need their landlord's consent.
What about a bathroom in a listed building?
Listed building consent can be needed for internal changes, not just external ones. Speak to your council's planning service before any work is designed.
