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Revolutionising Construction: How Factory-built Bathrooms are Driving Efficiency

In this article, James Stephens, Managing Director of the UK’s leading bathroom pod manufacturer, Offsite Solutions, offers some practical advice for specifying and procuring factory-built bathrooms.

Bathroom pods have revolutionised traditional construction methods and are now widely used for student accommodation, care homes, hospitals and housing – from high-end luxury apartments to social housing. The approach uses off-site manufacture in parallel to, or ahead of the on-site construction schedule. This brings a range of benefits.

The number of activities and trades on site are radically reduced. This achieves significant programme savings, quality improvements and reductions in waste of up to 50 percent compared to traditional construction.

On a large-scale, complex residential project, the programme saving can be as much as 20 weeks. This delivers cost savings on site preliminaries, waste removal and reduced snagging. There is a faster return on investment for the developer or earlier occupation for the client – as well as much greater certainty of completion on time and to budget.

Reducing Waste to Unprecedented Levels

Bathroom pod manufacture uses lean production techniques and better management of materials. This allows improved quality control, more efficient use of permanent, highly skilled labour, and less reliance on subcontracted trades. These factors combine to help to reduce waste levels in the factory to below 1 percent.

The production line environment of pod manufacture offers consistently higher quality standards and much greater project certainty. Pre-delivery testing is rigorous and quality assurance procedures are stringent for ready-to-use installation.

What are the Different Pod Types?

There are three key pod types – steel, concrete and GRP:

• Steel-framed pods – applications are typically large-scale residential apartments, hotels and student accommodation, and these pods offer a premium aesthetic and a high degree of design flexibility.
   
• GRP pods are widely used for student accommodation, social housing and healthcare projects. They have the benefit of lower capital expenditure and ease of maintenance, and are very easy to keep clean, robust and durable. With the latest GRP pod technology, a realistic tile effect is also now possible.
  
  GRP pods from Offsite Solutions use a unique panellised system which creates vertical walls and 90° corners. This design improves aesthetics by avoiding tapered walls which you have with pods created from complete GRP moulds.
   
• Concrete pods are much less common due to the higher loadings, but they are occasionally used for secure institutions such as prisons.

New innovations in bathroom pods include:

• Concrete floors – these are hybrid concrete/steel bathroom pods with a concrete base and steel-framed walls. These are being used for high specification residential projects which is a significant growth area for factory-built bathrooms.
   
• Demountable pods – Bathroom pods have traditionally been limited to new build projects. However, the development of ‘demountables’ extends their use to refurbishment schemes. Initially developed by Offsite Solutions for MoD refurbishment projects to convert bedrooms to ensuite accommodation, their use for student residences is now increasing. In commercial to residential conversions and some new build schemes, there may be insufficient access for fully assembled pods. Other potential applications include hotel and healthcare refurbishment.
  
  In these projects, the only access may be through a window opening of an existing building – or internally via the main entrance, and this may not be sufficient for a full-sized pod. Panel sizes of a demountable pod are specially designed to ensure full access is achievable, for example, via stairways or openings in the façade.
  
  The sectional design of Offsite Solutions' GRP demountable pod allows 10 pods to be delivered, sited and installed in just 3 days, with the superior quality of factory-built bathrooms and a single point of contact. Site-built bathrooms on a typical residential scheme take 6-12 weeks to complere using multiple trades and a high level of site management and supervision.
   
• Hybrid GRP pods - Unique to Offsite Solutions, this pod type allows an enhanced level of finish and improved aesthetics for GRP pods, such as ceramic tiling and recesses. Applications are typically hotels and apartments, and hybrid pods are increasingly common in the build-to-rent sector aimed at young professionals to help differentiate the accommodation from student residences.
   
• Floorless pods – Pods supplied without floors can be a useful option for projects where a continuous floor finish is required throughout a building; for DDA compliance requiring floors with no threshold, or for the ground floor of a building where the pod needs to sit above drainage routes which have been cast in.?

How are Pods Installed?

Factory-built bathrooms are generally delivered on a supply only basis and the main contractor organises installation. It is usual for the M&E contractor to undertake connections. The exception is demountable pods for refurbishment projects, where Offsite Solutions would install and assemble the pods.

Typically, 10 GRP pods would be offloaded on site, lifted, positioned and levelled in two hours – or 6-8 steel-framed pods. It can take around 80 hours for a site-constructed bathroom to be completed, compared to around 14 hours for a factory-built bathroom. Site-based construction requires around seven different trades and 10-15 operations on site plus the required drying times. With off-site construction, this is reduced to just one bathroom pod supplier, which means much less risk of programme delay and quality control is far greater, mitigating defects and remedial works.

A high quality, flat and level finish is needed for efficient installation. Bathroom pods are designed to interface efficiently within a building and very little site work is needed for successful installation.

Key Specification Considerations

1. Early Engagement

For optimal efficiency, early engagement is essential and pods should be designed into the early stages of a construction project. This will reduce the likelihood of access issues at the installation phase.

Bathrooms are often designed to be different but for no practical benefit. Specifiers should recognise that repeat designs are more efficient and cost-effective for factory-built bathrooms, to drive construction efficiency.

2. Consider Access

It is critical to accommodate access for pod installation in the build-up of the building Look at how the building will be constructed and how the pods can be installed. And take account of access for delivery of the pods to the site – this is particularly important for constrained city centre sites. A single trailer can accommodate six steel/residential pods, or 10 GRP pods for student accommodation or healthcare.

3. Look at Economies of Scale

Standardised designs with minimal variations allow the client to benefit from cost savings and time efficiencies by using the repetition of the modular production process. A good manufacturer will offer an extensive library of pod designs which customers can draw on to save time and cost. This allows the modular process to be enhanced by the repetitious production schedule of standardised products.

However, pods can also be completely customised to suit the individual requirements and specification of a particular scheme. Bespoke designs need to allow for modelling, prototyping, production engineering, machine programming and production line set up – and for GRP pods, the manufacture of the moulds.

Left and right hand versions of a pod are variations but the number of pod types will include differences in shape or size. We would always advise rationalising the number of design types and variations as far as possible to optimise efficiency.

• Steel – for example, a 400 pod project may have eight-bathroom designs. Be aware of variations within that – such as left/right hand, location of fan, vent, soil pipe etc

• GRP – a good pod manufacturer will have an extensive range of standard pod types so smaller numbers can be achieved cost-efficiently

• Bespoke GRP pods – these can be designed and manufactured but tooling costs will apply so this solution is more suited to larger-scale projects.

4. How will Pods Integrate with Building Services?

Building designers must allow for pod installation in the build-up of walls and floors. Connections to services are made externally so access should be allowed for as part of the installation process. Connections from inside a pod are possible but are much slower to achieve on site and have quality implications.

A good pod manufacturer will design the pods to facilitate and speed up installation on site. For example, there can be mechanically-fitted pan connectors and the option of a pre-wired junction box to simplify electrics.

Other design considerations:

• It is possible to vary the thickness of the pod base according to project requirements and the size of the pod

• Be aware that natural materials such as marble and granite do not transport well and these finishes are not uniform so the typical tolerances that a pod manufacturer will work to may not be possible

• Make sure the building structure can support a pod – although the typical weight of a steel or GRP pod is close to the weight of a site-installed bathroom. With steel-framed pods there are eight-point loads to take the weight of the pod – this needs to be accounted for in the structural loadings

• The floor slab should be flat and level to +/- 10mm tolerance for accurate installation.

How to Select a Pod Manufacturer

1. Check Guarantees and Accreditations

The bathrooms should be manufactured to ISO 9001 standard for quality assurance and ISO 14001 for environmental management.

All pods should be certified before delivery to site and supplied with a unique ID number so they are fully traceable throughout their life for superior quality control.

The manufacturer’s guarantees should be 12 years for steel-framed construction and 50 years for GRP composite pods, with back-to-back guarantees for sanitaryware and fittings.

2. Customer Service Commitments

Be aware when comparing tenders that not all manufacturers are like for like in their service commitments. We would advise making sure that the pod manufacturer has:

• Inhouse design resources, for example, to advise on materials that perform well in a pod environment

• A dedicated site manager who will visit site at regular intervals

• A robust testing regime before the pods leave the factory – look at the procedures closely

• After sales support to advise on any installation issues, for example.

• What is the manufacturer’s commitment to innovation?
   
• What design options are available, such as hybrid, floorless and demountable pods, and other specification options such as concrete floors, underfloor heating, and heated walls?
   
• Does the manufacturer have a proven track record in your sector?

• What percentage of projects has been delivered on time and on budget? Off-site manufacture should offer greater certainty of delivery on programme – but any delays could delay the wider construction schedule

• What level of testing and inspection is carried out prior to delivery to site? A stringent testing regime is essential.

Building bathrooms on site is inefficient and often causes issues with delays, health and safety management, and poor workmanship which impacts on quality and defects.

By contrast, factory-built bathrooms are delivered to site ready for installation, providing a quality of finish that is simply unachievable consistently on a building site. Cutting-edge manufacturing technology and quality-controlled production ensures each bathroom pod is delivered to site as a complete, fully tested unit – and this is revolutionising the efficiency and sustainability of construction across a host of sectors.

To attend a CPD seminar to find out more about factory-built bathrooms, visit www.offsitesolutions.com/CPD.