17 Mar 2017
The Housing White Paper — 'Fixing our broken housing market'* — states that the government seeks to boost productivity and innovation by encouraging modern methods of construction (MMC) in house building and to promote more modular and factory built homes.
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MMC are taken to include homes that are built off-site or can be rapidly assembled, or use other building techniques that increase productivity.
Following discussion with officials from the Department for Communities and Local Government (DCLG), BCIS would like to assist them in their study of the MMC market, particularly in identifying the barriers limiting the implementation of off-site manufacture in the residential market. In addition, we are involved with the Construction Leadership Council regarding construction innovation, particularly factory manufacture of homes.
The cost of off-site construction
Previous, if somewhat dated, research carried out by BCIS for the NAO** suggested that off-site construction was more expensive, but had the potential to be significantly faster than traditional construction, however the projects were often not organised to take advantage of this quicker construction.
Within the BCIS database we code projects with a significant amount of off-site construction separately. We also identify timber-framed construction separately, but do not classify this as off-site construction.
At present our sample size for "off-site" schemes is very low, looking at a sample of over 1000 housing schemes*** on our database, with less than 2% identified as off-site. The BCIS sample is by no means random but it is indicative of the slow progress of this sector to date.
To make informed decisions the government requires more data on MMC schemes.
Join the debate
We welcome readers' views and experience on this subject, particularly:
- Identifying the barriers limiting the implementation of off-site manufacture in the residential market
- Names/types of MMC currently being used
- Potential savings in time/contract duration as a result of off-site construction
- Comparator indicators with conventional build, particularly:
- pre-manufactured value, expressed as proportion of construction cost at point of delivery on site (£)
- time on-site to completion, expressed in days per m2
- preliminaries cost per home built (£)
- quality and energy efficiency of completed buildings
We welcome details of contract sum analyses for schemes using off-site construction methods for inclusion in the BCIS database.
Please email RICS Head of Project Data Alan Carter to participate
Defining off-site construction
The following graph shows an analysis of the costs available on the BCIS database, given the very low sample (less than 10 projects) and the difficulty in defining off-site construction. It needs to be viewed with caution but it does indicate a slightly lower cost for off-site construction for flats and a higher cost when using off-site construction to provide houses. This is the construction cost only and does not reflect any savings or benefits that might derive from speed of construction and improved construction methods.
Cost analysis data taken from the BCIS Online database
- * Fixing our broken housing market, February 2017
- ** Using modern methods of construction to build homes more quickly and efficiently — National Audit Office, November 2005
- *** Sample selection both ‘Estate housing – two storey’ and ‘Flats’, 2009 to date adjusted to 1Q 2017 prices (based on a Tender Price Index of 290) and UK mean location (Location index 100).
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