Requirement

Housebuilder Crest Nicholson needed a fast build method to erect three show homes and the first phase of its Silk Meadows housing development in Somerset. The company chose H+H’s Rå Build method of thin joint aircrete construction, together with retro-fit joist hangers which helped to speed up the construction even further.

Products used

Rå Build thin joint cavity wall with an aircrete inner leaf and brickwork external masonry outer skin.

Foundations

Strip foundation supporting 300mm Celcon Foundation Blocks in Standard Grade (3.6N/mm2 compressive strength) and High Strength Grade (7.6N/mm2 compressive strength).

External and internal separating walls

External cavity walls were constructed with an inner leaf of 610 x 270 x 100mm Jumbo Bloks. Both Standard Grade (3.6N/mm2) and High Strength Grade (7.6N/mm2) Jumbo Bloks were used depending on the compressive load. The wall has a 100mm cavity filled with blown expanded polystyrene bead insulation. The external wall is constructed of either brick or 100mm rendered dense aggregate block. The separating wall used two skins of 100mm Standard Grade Jumbo Bloks with a 75mm tied cavity. This enabled one block type to be used for both external and internal separating walls and achieved Robust details E-WM -10. A parge coat of cement mortar was applied to the separating walls before finishing with plasterboard. External walls were finished internally with plasterboard stuck on dabs and given a plaster skim finish.

Outcome

The Rå Build method enabled Crest Nicholson to complete construction of the show homes, which included a three-storey house, in just 12 weeks.