Outputs

A key challenge for the AIMCH developer partners was a methodology to derive the most effective things to standardise. All partners had wide ranging views, believes and perceptions, which made it difficult to establish a common approach and methodology for selecting things to be considered further.

The project developed a down selection methodology and scoring system to evaluate standardisation opportunities.

The MTC provided non-partisan facilitation, using previous methodologies and tactics derived within the automotive industry. This led to several workshops, hosted by MTC, where developer information was shared and discussed in a collaborative way.

These workshops led to the creation of a long list of 18 standardisation topics. All topics had merit, but it was clear a means to filter these was needed. This led to the following down selection process:

1. Set selection criteria definitions.
2. Assemble list of product families to be standardised.
3. Scoring of the product families.
4. Shortlisting of critical product family concepts.

Setting the selection criteria was important. This derived 13 key selection criteria, including commercial benefit, consumer impact, ease of implementation and build certainty. Linked to this was a scoring scale to evaluate impact for each criterion. A matrix was developed.

1. External Apertures – Windows and Doors
2. Service Cupboards – Electrical/Utilities Areas and Hot Water Storage Spaces
3. Storey Heights – Considered with the DFMA Guide
4. Wet rooms – Bathrooms, En-suites and WC’s
5. Staircases and landings – excluding handrails/newels

These were then developed in much greater detail through Detailed Standardisation Studies and Product Family Recommendations.

A significant part of this work package was the completion of detailed standardisation studies. These were undertaken by the AIMCH developer partners using their current housing portfolio ranges. The developers worked innovatively together to share information. 99 homes were analysed in total.

1. External apertures – windows & doors
2. Service cupboards – electrical/utilities areas and hot water storage spaces
3. Storey heights – considered with the DFMA guide
4. Wet rooms – bathrooms, en-suites and WC’s
5. Staircases & landings – excluding handrails/newels

The studies involved detailed evaluations of the standardised opportunities identified within the down selection process. Each developer focused on studying at least one area.

The studies investigated the influencing factors and constraints, around the issues of achieving coalescence of standardised outcomes. Often this is limited by external factors out with the developers controls such as differing building regulations.

The AIMCH developer's were at varying levels of housing portfolio design maturity. The cross section of expertise was highly beneficial in recognising the differing developer challenges in embracing, leveraging and implementing design standardisation.

The studies were most illuminating. They highlighted the lack of standardisation that exists within a developer, between developer and as an industry. It also highlighted how the evolution of housing portfolios overtime have created high levels of variability.

The studies concluded with specific recommendations on standardised product families and governance measures for each area studied. The concept being a kit of standardised common parts or sub-assemblies, that can be individually or collaboratively procured and integrated into future housing designs.

In doing so, this approach to standardisation, can yield significant commercial, business and housing delivery benefits, without detracting from brand values and consumer appeal, whilst also complying with UK regulatory variations.

A significant part of this work package was the completion of Product Family Recommendations.

1. External apertures – windows & doors
2. Staircases & landings – excluding handrails/newels
3. Wet rooms – bathrooms, en-suites and WC’s
4. Storey heights – considered with the DFMA guide

The work produced specific recommendations on standardised product families and governance measures for each area.

Through supply chain engagement, further benefits could be realised through optimised window production, raw material optimisation, handling and protection, with a view to reducing cost, waste and transportation.

These product families will be developed further, with supply chains and the creation of industrialised kit of parts, suitable for use within future AIMCH housing designs & in the creation of Industrialised Housing Pattern Books.

The work concluded be recommending the dimensions most readily suitable for standardisation. This led to a 3 tier standardised system approach. Tier 1 (Green) being the Top 10 most used dimensions, representing at least 71% of window openings needed in a conventional commonly derived house design. The Top 10 all fall within a common suite of parameters that provide reasonable coverage and compliance across the UK.

Tier 2 (Amber) sizes impact to a lesser extent but offer a wide range of standardised sizes, to suit a wider range of parameters. Tier 3 (Red) are outlier sizes, which attract technical and commercial implications.

The report goes on to evaluate external door openings. A key finding was the potential to derive a common single front/rear door brick opening size.

The study assessed the current state of variability within opening widths, depths and height clearances of stairwells. Stairwell openings are driven by internal layouts, floor to floor heights, clearance values and handrail/newel preferences, as well as regulatory requirements.

All AIMCH developers work to varying floor to floor heights, due to differing joist depths, floor make ups and internal ceiling heights. This is a challenge, however there is strong potential to coalesce around a common floor to floor height, including a small tolerance provision to allow flexibility in joist depth.

Stair manufacturing supply chains were engaged, on dimensional optimisation and coordination from a manufacturing perspective.

The work concluded be recommending the opening and floor to floor height dimensions, most readily suitable for standardisation, across the AIMCH developer partners and the wider housing industry.

The study highlighted the potential for a set of modular common stair parts within a staircase design that has potential for unilateral adoption across the staircase supply chain and by developers.

A key conclusion from the research study, was the critical requirement to have a common floor to floor height. The study coordinated panelised MMC systems such as timber frame, common plasterboard sizes and timber engineered joists, to determine a common floor to floor dimension suitable for floor joists ranging 235 – 241mm.

Wet room layouts are driven by internal layouts, spatial requirements, sanitary ware, fitted furniture, developer specifications/finishes and brand preferences, as well as regulatory requirements.

The study reviewed actual wet room layouts, configurations and sizes components across the AIMCH developers. All the AIMCH developers have a high degree of variation in wet rooms. This is a significant challenge to overcome, however there is strong potential to coalesce around a common range for wet room layouts, configurations and sizes.

The recommendations culminated in a suite of wet room layouts and configurations. The studies identified 4 common bathroom layouts, 4 common en-suite configurations and 3 common cloakrooms. The study focused on the dimensional setting out, layout configurations and spatial design to allow flexibility in fit out and door orientation of standardised wet room designs.

Standardised bathroom and en-suite pods, have commercial promise, albeit viability and technical challenges remain. These could be prefabricated as industrialised sub assembly solutions and could be adopted in an industrialised housing design of the future.

A hybrid pod and panelised MMC construction method could be feasible. However further considerations are needed, for example, additional floor area to cater for one, two and three side pod locations and floor levels to cater for pod base designs, as well as service connections points and fire integrity of the main superstructure.

Cloakroom are less likely to be commercially viable as prefabricated sub-assembly pods, due to the simplicity and cost effectiveness of current conventional construction methods.

In the longer term, through AIMCH housing design and further supply chain engagement, optimised pod production and volume procurement, should reduce cost and achieve a commercial tipping point, that fuels mainstream adoption of this hybrid MMC construction method. This work will be taken forward within the AIMCH supplier sandpit selection process during 2021.