05 June 2017
How Factory-built Bathrooms are Revolutionising Construction
In this article, James Stephens, Managing Director of bathroom pod manufacturer, Offsite Solutions, offers some practical advice for specifying factory-built bathrooms.
Bathroom pods have revolutionised traditional construction methods and are now widely used for student accommodation, hospitals, hotels and housing - from luxury apartments to social housing. The approach uses off-site manufacture to bring a range of benefits to improve the efficiency of construction.
The number of activities and trades on site are radically reduced, resulting in significant programme savings, quality improvements and waste reductions of up to 50%.
On a large-scale, complex residential project, the programme saving can be as much as 20 weeks. This reduces the cost of site preliminaries, as well as waste removal and snagging. There is a faster return on investment for the developer or earlier occupation, as well as much greater certainty of completion on time and to budget.
What are the Different Pod Types?
There are three pod types:
- Steel-framed pods - offer a premium aesthetic and a high level of design flexibility. Applications include large-scale apartments, student residences and hotels.
- GRP pods - widely used for student accommodation, social housing and hospitals. They require lower capital expenditure and are easy to maintain and clean. GRP pods from Offsite Solutions use a unique panellised system which creates vertical walls and 90° corners for improved aesthetics by avoiding tapered walls.
- Concrete pods - less common due to the higher loadings. Used occasionally for secure institutions such as prisons.
New innovations include:
- Hybrid concrete/steel pods - using a concrete base and steel-framed walls for high specification luxury apartments.
- Demountable pods - extending the application of pods to refurbishment with the use of a sectional structure. In commercial-to-residential conversions and some new build projects, there may not be access for fully assembled pods. Panel sizes of a demountable pod are designed to ensure access, for example, via the main entrance or façade openings. 10 demountables can be installed in just 3 days, with superior quality and a single point of contact. Site-built bathrooms can take 6-12 weeks to complete requiring multiple trades and extensive site management.
- Hybrid GRP pods - Unique to Offsite Solutions, these allow an enhanced finish and improved aesthetics such as ceramic tiling and recesses. Applications include PRS schemes.
- Floorless pods - Pods without floors can be a useful option for projects where a continuous floor finish is required throughout a building or for DDA compliance requiring floors with no threshold.
How are Pods Installed?
Factory-built bathrooms are delivered on a supply only basis and the main contractor organises installation via the M&E contractor. The exception is demountable pods, where Offsite Solutions would undertake installation and assembly.
Ten GRP pods can be installed in two hours - or 6-8 steel-framed pods. It can take around 80 hours for a bathroom to be built on site requiring around seven different trades and 10-15 operations plus drying times. A pod can be manufactured in 14 hours with just one supplier, which means improved quality, mitigating defects and remedial works.
Key Specification Considerations
1. Early engagement - essential to achieve optimal efficiency by designing pods into the early stages of a construction project.
2. Consider access - accommodate pod installation in the build-up of walls and floors. Take account of access for delivery of the pods to site, particularly on constrained sites.
3. Look at economies of scale - standardised designs with minimal variations allow cost savings and time efficiencies by using the repetition of the production process. A good manufacturer will have an extensive library of pod designs which customers can draw on. Pods can be bespoke but specifiers need to allow for modelling, prototyping, production engineering, machine programming, production line set up - and the manufacture of GRP moulds. To optimise efficiency, specifiers should rationalise the number of design types in size and shape, and variations, such as left and right hand versions, as far as possible.
4. Integrating pods with building services?
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 slower on site and affect quality. A good manufacturer will design the pods to facilitate installation, using for example mechanically-fitted pan connectors and the option of pre-wired junction boxes to simplify electrics.
Other design considerations:
- The thickness of the pod base can be varied according to project requirements and the size of the pod
- 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 weight of a steel or GRP pod should be close to the weight of a site-constructed bathroom. With steel-framed pods there are eight point loads to take the weight of the pod and account for in the structural loadings
- The floor slab should be flat and level to +/- 10mm tolerance for accurate installation.
To attend a CPD seminar to find out more about factory-built bathrooms, visit www.offsitesolutions.com/CPD
