Let’s take a quick look at what’s required in a specific example, including the process, step-by-step, for those who need a building control sign-off for their garden room build. In this particular example, we show a customer who wants a garden room with a toilet and shower, which needs to be built close to a boundary.
Table of Contents
Case Study: Garden Room With Bathroom Near a Boundary
Understanding Building Regulations for a 20m² Timber Garden Room
The Brief
This homeowner wanted to build a detached timber garden room in their rear garden to use as a flexible home-working and leisure space. The proposal included:
- A 20m² internal floor area
- Timber construction
- A toilet and shower
- Located within 1 metre of the boundary
- No sleeping accommodation
At first glance, many homeowners assume garden rooms are “exempt” from Building Regulations. This project is a good example of why that isn’t always the case.
Visit my other article to understand exactly when a garden room requires building control or building regulations approval: https://wood-create.com/when-does-a-garden-room-require-building-regulations/
The Key Question
Does this garden room require Building Regulations approval?
Yes, Building Regulations approval is required.
In this scenario, the project triggered Building Regulations for multiple reasons, not just one.
Why the exemption did not apply
Although some detached outbuildings can be exempt, this proposal fell outside the exemption rules because:
- A WC and shower were included
Any building with plumbing connected to foul drainage is almost always in scope. - The building was 15–30m² and within 1m of a boundary
This alone removes the exemption. - Timber is a combustible material
Fire safety requirements apply more strictly near boundaries.
Even without the bathroom, the size, material, and boundary distance would still have required approval.
Who Needed to Be Notified?
Before work started, the homeowner needed to notify Building Control. There are two routes:
Option 1: Local Authority Building Control (LABC)
- Application made via the local council
- Common choice for domestic projects
- Clear inspection process
Visit the LABC website here: https://www.labc.co.uk/
Option 2: Approved Inspector
- Private building control company
- Sometimes faster, fees vary
You can find a list of approved building control companies here: https://www.find-a-building-control-approver.service.gov.uk/public-register-england/results?building-control-approver=&browse-all=true
👉 In this case, Local Authority Building Control was the most suitable option.
The Application Process
Step 1: Choose the Right Application Type
For a garden room with drainage, fire safety considerations, and insulation requirements, a Full Plans application was recommended.
- Drawings approved before construction
- Clear compliance strategy
- Fewer surprises on site
A Building Notice was possible but carried more risk and was not ideal for this type of build.
Step 2: Submit Technical Information
The submission included:
- Site plan showing distances to boundaries
- Floor plans and elevations
- Foundation and structural details
- Wall, roof, and floor build-ups
- Drainage layout for WC and shower
- Ventilation strategy
- Electrical and plumbing intent
What Building Control Assessed
Building Control reviewed the project against several Approved Documents.
Structure – Approved Document A
- Foundations sized for soil conditions and timber construction
- Timber frame sizing and bracing
- Roof structure designed for wind and snow loads
- Properly constructed floor build-up
This was assessed as a habitable-standard structure, not a shed.
Fire Safety – Approved Document B
This was a critical element due to the building’s proximity to the boundary.
Requirements included:
- Fire-resisting external wall construction
- Restricted or no glazing on the boundary-facing elevation
- Fire-resistant internal linings
- Consideration of fire spread to neighbouring land
Drainage & Plumbing – Approved Document H
Because the building included a WC and shower:
- Correct foul drainage connection
- Proper pipe gradients
- Traps and ventilation
- Inspection access where required
This was one of the primary reasons approval was unavoidable.
Ventilation – Approved Document F
- Mechanical extract ventilation for the shower room and WC
- Minimum airflow rates achieved
- External discharge of moist air
Energy Efficiency – Approved Document L
As a habitable garden room:
- Insulated walls, roof, and floor
- U-values meeting current standards
- Thermally efficient doors and glazing
Garden rooms with bathrooms are treated far more like small dwellings than storage buildings.
Electrics – Approved Document P
- All fixed electrical work complied with Part P
- Installation carried out by a registered electrician
- Electrical certification provided at completion
Water Safety – Approved Document G
- Hot water temperature control (scald prevention)
- Water-efficient sanitary fittings
Access – Approved Document M (Limited Scope)
- Reasonable access provided
- Appropriate thresholds and door widths
- Not full wheelchair compliance, but basic accessibility principles applied
Inspections During Construction
Building Control inspections were required at key stages:
- Foundations (before concrete pour)
- Drainage (before backfilling)
- Structural frame
- Insulation (before internal linings)
- Final completion
Inspections were booked by the homeowner/builder as work progressed.
The Outcome
Once all works were completed and signed off:
- A Building Regulations Completion Certificate was issued
- The property records were protected for future sale or remortgage
- The garden room was fully compliant, insurable, and fit for long-term use
This certificate is essential. Without it, homeowners risk enforcement action and complications when selling their home.
Planning Permission: A Separate Consideration
Although this case focused on Building Regulations, planning permission was checked separately.
In many cases, a garden room with a bathroom can still fall under permitted development, but height, location, and use must comply. Planning and Building Regulations are two different systems, and both must be considered.
Read the full planning permission guide here.
Key Takeaways for Homeowners
- Garden rooms are not automatically exempt from Building Regulations
- Adding a bathroom almost always brings a project into scope
- Boundary distance and timber construction significantly affect fire safety requirements
- A Full Plans application reduces risk and uncertainty
- A Completion Certificate protects your investment
Further Reading
You might find some of these articles handy if you’re designing and building your own garden room:
