Changes to government funding structures for social housing allow Councils, for the first time in nearly thirty years, to build directly owned houses for rent. Capitalising on these changes, Ashford Council embarked on a programme of building adding to the council owned portfolio, using private sector finance to fund the development.
MFS were asked to design and build 44 brand new council houses. The development comprised a range of dwellings including: bungalows, semi-detached and attached houses. In addition there were some apartments and a care unit for elderly residents.
Location: Ashford in Kent
Client: ISG Jackson, Ashford Borough Council
Build Type: Residential Low Rise and Care Homes
No of Units: 44 houses over 11 sites
Status: Completed Project.
Build Duration: Completed October 2011, 21 weeks on various sites in Ashford.
MFS System: H+H Celcon Thin Joint Blocks
Additional build requirements:
- Structural steel frame
- Precast concrete floor planks
- Roof trusses
- Cavity wall insulation
- Brickwork & Monocouche render
MFS were able to take full advantage of our thin joint block system and carried out all the structural envelope construction including:
- Internal and external block work leaves
- Intermediate and PCC separating floors
- Trussed roof construction
The 44 units were delivered within a 21 week programme with four sites under construction at any one time. The builds were carried out in 11 different sites throughout Kent.
This was phase two of a multi-staged project to build new council homes on existing council-owned land. Typical sites for the project included disused garages and areas of waste ground between developments.
The dwellings were all built to Code Level 4 of the Code for Sustainable Homes. Although in advance of the existing building regulations, this objective fitted with the government aim of encouraging government agencies to increase standards of sustainability.
To achieve this rating, the construction elements needed a high level of thermal insulation. The Rå Build method using the H+H Thin Joint masonry system was specified using Jumbo Bloks. Fully filled cavities were combined with either aircrete or brick outer leaves.
This is not only an extremely fast and efficient method of building, but also provides substantial benefits in reducing heat loss. In designing the wall structure, the use of aircrete’s very low psi values, based on Accredited Construction Details, allowed a halving of the y-value from 0.08 to 0.04 W/m2K. This is used to calculate the impact of linear thermal bridging within SAP 2005. The 0.04 y-value is achieved by virtue of the thermal efficiency of aircrete, without the need to resort to Enhanced Construction Details, and has a similar effect on all external elements.
Wherever possible the contractors used aircrete for both leaves of the external walls in order to fully capitalise on the inherent thermal efficiency of aircrete. The outer leaf was then finished with a through-colour monocouche render.
High performance full-fill cavity wall insulation manufactured by Superglass was used in the 125mm cavity. The structural width of the whole cavity wall was no more than 325mm with a U-value of 0.19W/m2K using two Thin Jointed leaves of 3.6N/mm2 aircrete. However, taking into account the 0.04 reduction in the y-value meant that the walls effectively provided a U-value of 0.15W/m2K.
To complete the energy efficiency of the build, solar PV panels were used on the roof of the dwellings. It was necessary to include some renewables in this project to achieve Code 4 level, but the contractors did note that the very thermally efficient structure significantly reduced the PV requirement.
With 44 units including 18 apartments on eleven separate sites, all with different dwelling types, Rå Build, using Thin Joint technology, provided a simple approach at design stage, plus vital programme flexibility on site. The large format blocks and thin layer mortar are ex stock, and simply called off as required, making delivery and storage of blocks a straightforward issue for the contractor. As an H+H Recommended Contractor provided all masonry frames across eleven separate sites the programme control was greatly simplified.
We wanted to go with an all masonry solution for several reasons. We wanted a really robust solution to help with our longer-term planned maintenance programme and feel that masonry provides us with the reassurance of a really solid structure. We also considered that airtightness that the Rå Build method offers, particularly the assurance that this level of airtightness will be maintained over time. The masonry solution also gave us the flexibility to include bespoke designs – which is key to the success of this project, given the nature of the sites we were developing.
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