From Vacant Space to Vibrant Community Hub: The Transformation of Unit NU2 into an Indoor Swimming Pool

In the heart of Birchwood’s commercial quarter on Dewhurst Road lies Unit NU2 — a space that for too long stood vacant, a blank canvas waiting for a project with purpose. Today, that purpose is becoming reality. What was once an unoccupied retail unit is now set to be transformed into a vibrant indoor swimming pool facility by Time to Swim, offering health, leisure and wellbeing benefits to the local community. With planning application 2025/01365/FUL now approved, the focus of the project has shifted into one of the most technically demanding phases of development: building control.

This blog post walks you through the journey from retail vacancy to aquatic centre, highlighting the importance of planning approval, and digging deep into what the building control phase really means — not just in theory, but in practice — for a conversion of this scale.

A Site Ready for Renewal

Unit NU2, located at Dewhurst Road, Birchwood, Warrington, WA3 7PG, is part of a modern commercial block that has historically housed a variety of retail tenants. As shopping habits changed and occupancy fluctuated in recent years, NU2 became one of the units most affected by transition — a space without a permanent tenant, missing out on the vibrancy its neighbours continued to enjoy.

Yet the location itself — close to residential neighbourhoods, transport links, and other community amenities — made NU2 a prime candidate for an adaptive reuse project. Enter the vision to convert what was a vacant retail unit into an indoor swimming pool, a facility that not only adds value to the local leisure infrastructure but meets a clear, articulated need in the community.

In early 2025, the project took a key step forward with the submission of planning application 2025/01365/FUL to the local planning authority. This application sought approval for the change of use of the unit from retail (Use Class E) to leisure (Use Class D2) — specifically, an indoor pool with supporting facilities.

Understanding Planning Application 2025/01365/FUL

Before any physical redevelopment could begin, the project needed planning permission. Planning officers and local stakeholders needed to be confident that the proposed indoor pool would:

• Respect the character and appearance of the Dewhurst Road commercial area

• Not unduly impact neighbouring properties in terms of noise, traffic or privacy

• Meet highway, access and parking requirements

• Demonstrate high standards of design, sustainability, and inclusive access

Planning application 2025/01365/FUL underwent review against local planning policy and national guidance. Officers assessed the proposal’s impact on the environment, the movements generated by daily pool users, and considerations like hours of operation, waste management, and landscaping.

When Warrington Council granted planning permission, it essentially confirmed that the proposed change of use was acceptable in principle. This was a milestone — but by no means the end of the technical journey. With planning permission approved, the project team could now turn its full attention to building control — the rigorous regulatory process that ensures what gets built is safe, functional, and compliant with the Building Regulations.

What Is Building Control — And Why It Matters

Once planning permission is in hand, developers often breathe a sigh of relief. But that relief is short-lived. The next phase — building control — is the phase that really transforms drawings and ideas into a structure that people can safely enter, use and enjoy.

While planning permission deals with land use, how a building looks, and its impact on surroundings, building control deals with how the building works. It is statutory, compulsory, and detailed down to individual components — from fire safety and structural soundness, to drainage, accessibility, insulation and energy performance.

For a change of use project like Unit NU2, the building control phase is where the real technical rigor begins. This is where engineers, architects, mechanical and electrical consultants, and building control officers come together to ensure the converted space isn’t just attractive — it is robust, safe and built to last.

Let’s break down what this means in practical terms.

Building Control Requirements for an Indoor Swimming Pool Conversion

1. Structural Design and Assessment

At the top of the priority list is ensuring the existing building — once designed for retail display and customers — can safely accommodate the loads imposed by a filled pool, supporting plant equipment, and the circulation of people.

Indoor pools are heavy. Not heavy in the ordinary sense of building weight, but heavy because of the water. Water weighs approximately 1,000 kg per cubic metre, and even a modest pool can contain tens of thousands of litres. This places concentrated loads on floors that were not originally engineered to carry them.

In the building control phase:

• A structural engineer must assess the existing framework of Unit NU2.

• Detailed calculations are produced to confirm that columns, beams and foundations can support the pool structure and attendant loads.

• Where reinforcement is needed, designs are prepared for steel strengthening, slab reinforcement, or foundation works.

• These calculations and plans are submitted to the building control body for review.

Only when the building control officer is satisfied that the structure will be safe, stable and compliant with Part A (Structure) of the Building Regulations can construction proceed.

2. Waterproofing and Moisture Control

Pools produce continuous moisture and humidity. Left unchecked, this moisture can:

• Degrade building materials (especially timber)

• Cause corrosion in steel elements

• Encourage mould growth

• Reduce air quality

To prevent these risks, the building control submission must demonstrate a comprehensive waterproofing strategy:

• Membrane systems under the pool shell and in wet areas

• Sealant details around joints and interfaces

• Moisture-resistant finishes and materials where appropriate

• Detailing to prevent water ingress into walls, hidden cavities or adjoining spaces

Building control officers will require detailed evidence that the waterproofing design complies with Part C (Site preparation and resistance to contaminants and moisture).

3. Ventilation and Indoor Air Quality

Without effective ventilation design, an indoor pool can quickly become uncomfortable and unhealthy. Heat and humidity must be controlled to ensure comfort, prevent condensation, and protect the fabric of the building.

Building control focuses on Part F (Ventilation), requiring:

• Mechanical ventilation systems sized correctly to exchange air adequately

• Dehumidification equipment specified to manage moisture load

• Documented calculations showing airflow rates

• Strategies for heat recovery to improve energy efficiency

The building control officer will carefully review HVAC (heating, ventilation and air conditioning) designs to ensure that ventilation is not just present — but effective and energy efficient.

4. Thermal Performance and Energy Efficiency

Indoor pools are energy intensive spaces. Heat loss through water evaporation, glazing, and uninsulated surfaces can be significant. The Building Regulations address thermal performance under Part L (Conservation of fuel and power), requiring:

• High levels of insulation in walls, roofs, and floors

• Energy-efficient plant and controls

• Glazing that meets minimum U-values

• Continuous insulation detailing to prevent thermal bridging

During the building control review, designers must produce:

• U-value calculations for building elements

• SAP (Standard Assessment Procedure) related energy models where relevant

• Detailed specifications for insulation materials and locations

Compliance here supports lower operating costs and ensures that the facility aligns with broader sustainability objectives.

5. Fire Safety Measures

Fire safety is a central pillar of building control. Pools bring unique challenges: large open areas, wet surfaces, and spaces that might be hard to evacuate quickly if not designed properly.

Under Part B (Fire safety), the building control phase must respond to:

• Safe escape routes with non-slip surfaces and lighting

• Appropriate fire detection and alarm systems

• Fire compartmentation to prevent spread between spaces

• Fire-resistant materials where required

Plans are reviewed in detail, and building control inspections check that fire safety measures are implemented exactly as designed.

6. Accessibility and Inclusive Design

An indoor swimming facility must be welcoming and usable by everyone, including people with disabilities. In building control, this means complying with Part M (Access to and use of buildings), which addresses:

• Ramps, level changes, and clearances for wheelchair access

• Accessible changing rooms and toilets

• A pool lift or sloped entry where appropriate

• Tactile signage and wayfinding

The design team will submit accessibility drawings and justify compliance with relevant guidance, ensuring that the facility meets legal requirements and community expectations.

7. Plumbing, Drainage and Water Hygiene

Pools require complex plumbing and drainage systems, including:

• Water circulation, filtration and chemical dosing

• Overflow and waste water collection

• Backwash water disposal

• Hot and cold water supplies for changing rooms

These systems are reviewed under Part G (Sanitation, hot water safety and water efficiency), and building control must see evidence that:

• Drainage connects correctly to public sewers or private systems

• Waste water disposal complies with local authority requirements

• Plumbing systems are designed to prevent cross-contamination

Water hygiene standards also tie into health and safety regulations outside the Building Regulations themselves, meaning the building control submission must be coordinated with wider statutory health obligations.

Submitting the Building Control Application

Once the project team has collated all detailed drawings, calculations and specifications, they submit a building control application to either:

• The local authority building control service, or

• An approved inspector (a private sector alternative recognised by statute)

The application includes:

• Architectural and structural drawings

• Structural calculations

• HVAC design reports

• Fire safety strategies

• Plumbing and drainage schematics

• Insulation and energy compliance reports

• Accessibility plans

A building control officer (BCO) or approved inspector then reviews the documentation. They may issue queries, request revisions, or suggest refinements. This iterative process continues until the submission is deemed satisfactory.

Importantly, building control is not just a paperwork exercise. As construction progresses on site, the BCO carries out site inspections at key stages, such as:

• Foundations and structural reinforcement

• Pool shell installation

• Waterproofing application

• HVAC installation

• Fire safety systems installation

• Final completion checks

Only after successful inspections and verification does the building control body issue a completion certificate, which legally confirms that the building complies with the Building Regulations.

Without this certificate, the indoor pool cannot open to the public — making this phase absolutely critical for the project.

What This Means for Birchwood

The successful transition of Unit NU2 from a vacant retail unit to an indoor swimming pool facility promises significant benefits for Birchwood Shopping Centre and the wider Warrington area.

Community Health and Wellbeing

Swimming is one of the most inclusive forms of exercise — beneficial for children, adults, seniors, and rehabilitating patients alike. The facility will provide:

• Aquatic lessons and training programs

• Fitness and wellness opportunities

• A venue for community events

Economic Activity

The pool will create jobs — from construction employment during the building phase to operational roles once open. Nearby businesses may see increased footfall as visitors use cafes, shops and services in the vicinity.

Revitalising a Vacant Space

Instead of remaining a dormant shell, Unit NU2 will be fully occupied, contributing to the vibrancy of Dewhurst Road and reflecting a positive cycle of investment.

But none of these benefits are guaranteed without the building control phase being thoroughly executed. Safety, compliance and durability must be engineered into every aspect of the conversion.

Final Thoughts

While planning application 2025/01365/FUL unlocked the potential of Unit NU2, it is the building control process that will ensure this potential becomes a safe, functional and lasting reality.

Building control is where design meets regulation — where structural engineers, builders and inspectors collaborate to protect users, safeguard investment, and deliver a facility that the community can enjoy with confidence.

As the building control phase advances — from technical submission to on-site inspections and final certification — each milestone brings Birchwood one step closer to welcoming a much-anticipated indoor swimming pool.

Stay tuned here for updates on construction progress, key project milestones, and insights from the teams driving this exciting transformation forward.