Product / system manufacture
|Contract value (£)||
Total value of the block-work alone was approx. £300,000. The entire project value was £9 million.
Wrekin Housing Trust
McPhilips Ltd (main contractor), Minett Group (inner shell subcontractor), Repex Ltd (external insulated render subcontractor)
H+H UK aircrete blocks
This 53-unit flagship scheme offers accommodation with the necessary facilities to allow those with support and care requirements to live independently. The building is designed to integrate accessible dwellings, care resources and shared communal facilities in a secure environment, whilst being environmentally friendly. Rising up to four storeys high, the project is made up of a mix of 1- and 2-bedroom self-contained apartments for rent with extensive communal areas.
The entire development had to comply with Part E of the current Building Regulations covering Rooms for Residential Purposes. The minimum requirements being:
- Walls: minimum 43dB Dntw + Ctr;
- Floors: airborne, minimum 45dB Dntw + Ctr
- Impact: maximum 62dB Lntw.
- Separating walls: cavity masonry were constructed to Robust Details E-WM-10 and E- WM-13.
H+H aircrete contributes to the building’s high level of thermal insulation, and when coupled with high-efficiency boilers and rainwater recycling, the scheme achieved a BREEAM ‘very good’ rating.
The Rå Build method of construction with solid external walls, cavity separating walls, and PCC plank separating floors was the preferred approach, with an insulated external render. Approximately 110,000 H+H UK aircrete blocks were used in the build. To facilitate areas with brick facings, some of the external elevations are of cavity construction, with 100mm cavity. 100mm full-fill mineral wool was used. The entire interior is finished with plasterboard dry lining on dabs. A stand and seam aluminium clad roof completes the building.
Contractor Chase Norton was attracted to the robust simplicity of a solid external wall. The use of external insulated render means all the masonry is inside the envelope which, together with the use of concrete separating floors, creates a high thermal mass. The building will be slow to lose its heat in cold conditions, but will also remain cooler in the summer months, thus reducing the need for air conditioning. This slowing of the heating/cooling cycle, coupled with the building’s performance in sound control, will provide greater comfort for the occupants as well as reduced energy consumption. McPhilips won the contract to complete the job following the collapse of Chase Norton and were pleased with how it went.
“This was our first time with aircrete and I would be happy to use it again. The material enabled us to meet the criteria for using a modern method of construction and comply with or exceed required building regulations. We also had the confidence that comes with a familiar type of building process and well established trade practice”.
Tony Hewitt Project Manager, Wrekin Housing Trust
“We demonstrated with this project that the Rå Build method of construction with the thin-jointed aircrete is not just a quick fix to streamline the construction process, but also contributes to the thermal mass of a building.”
Richard Afford, Surveyor, Minett Group
“We found the H+H aircrete solid wall substrate to be very flat and it accommodated the render without any issues whatsoever. As the site was in a clean condition, we were able to complete our work quickly and on time”.
Andy Simmonds, Contracts Manager, Repex Ltd
- Construction programmes are simplified as the inner shell can be completed before external cladding by one contractor.
- Compliance with Part L and Part E of the Building Regulations.
- Lead time is kept to a minimum as all components for thin-joint block-work are available ‘off the shelf’.
- Block-work is design flexible and highly adaptable.
- Thin-joint blockwork has an air-tightness around 1m3/hr/m2.
- Approximately 75% less mortar is needed on site.
- Celfix takes up less storage area than traditional mortar.