Advanced Prototyping
As part of the AIMCH project, a number of advanced MMC prototyping trials were carried out on live developments. During this time the sites were also monitored to gain data in terms of resource and productivity. A summary of the work carried out is as follows:
- Monitoring from September 2019 – December 2021
- Over 80 units monitored across both developers
- Traditional masonry, open panel timber frame and closed panel timber frame
- Time, resource and waste being monitored
- Circa 1 million data points collected
- Over 30,000 operative hours recorded
This report aims to highlight some of the key findings from the monitoring relating to some of the advanced prototyping trials.
summary
The below highlight some of the key benefits the data identified as part of the advanced prototyping and monitoring:
- The data identified benefits in terms of productivity across all of the advanced prototyping trials.
- Constructing the roof on the slab is up to 22% quicker than building in-situ.
- Modular roof installation is up to 51% quicker.
- Utilising scaffoldless timber frame erect increases the speed of follow on trades, in particular bricklayers which saw a speed improvement of c.20 operative hours.
- The scaffoldless timber frame does not impact the productivity of the timber frame erect process, however alters the critical path of the build and has additional health and safety benefits.
- Offsite ground floor systems are over 60% more efficient than traditional systems.
- Single skin party walls have a positive impact of follow on trades and reduced the first fix time by c.34%.
JOURNEY
- Data was collected using BRE’s CaliBRE system, a toolkit to measure operative hours for the housebuilding process and determines operative efficiency
- A dedicated site observer collected data on each plot every 15 minutes using an iPad
- Data was collected on a plot specific basis and for the following areas:
- Plot
- Build stage
- Operative
- Work package (Build stage)
- Task
- Activity
- SmartWASTE data was also collected alongside the CaliBRE data by the site observer three times a day
- Waste was collected at the source (each plot) using site mini skips and is collected in volume (m3) and weight (kg) using a weighing scale
- Data can be broken down by different levels to give a deeper understand of when, where and why the waste was generated
ADVACNED PROTOTYPING TRIALS
A number of trials were carried out during the course of the project with varying levels of offsite construction, these include:
- Closed panel timber frame
- Factory fitted windows
- Chipboard decked floor cassettes
- Single leaf party wall
- Scaffoldless timber frame erect
- Felt and batten roof (on the ground)
- Fully tiled roof (on the ground)
- Offsite ground floor slabs
- GRP dormers
- Modular roof
Resources
Conclusion
To summarise the key findings from the advanced prototyping trials are:
- Building the roof structure on the ground has both health and safety and productivity benefits. The more advanced the roof system the more the increase in cost, however, the health and safety, waste and productivity benefits also increase.
- A significant percentage of the increase cost for the advanced roofs comes from the additional material required in the roof structure to lift the roof safely. A reusable roof beam that could be taken out of the roof once installed and used on multiple plots would make the advanced roof systems significantly more viable.
- The scaffoldless timber frame erect system does not impact productivity in relation to the timber frame. However, the system takes scaffolding off the critical path of timber frame construction, which is one of key reasons for delays on timber frame developments.
- If this system could be utlised in conjunction with an external cladding system that can be factory fit, this could potentially remove traditional scaffolding completely from the build having a major impacts on both cost and health and safety.
- Single skin party wall system are installed are a similar pace to a twin wall systems, the benefits of the system are demonstrated in the first fix which was c.34% quicker due to specific tasks relating to the party wall being installed offsite (e.g. insulation).
- Difficulties in the install of the offsite ground floor system resulted in a large portion of non-value and wasted time associated to the system. With that said, the system was still c.63% quicker than the traditional system and could increase to c.70% if non-value and waste was in line with other analysis.
- Timber frame is between 21-39% quicker than traditional masonry construction.
