The Airey Precast Concrete Constructed House
- Manufacturer: W Airey & Sons Ltd
- Construction Type: PRC
- Designer: Sir Frederick Gibberd
- Period Built: 1945-55
- Number Built: 26,000
Classified as defective by the Secretary of State under Part XVI of the Housing Act 1985 in England & Wales
The Airey House design was developed by Leeds-based builder, Sir Edwin Airey in the aftermath of the Second World War. It was built on Aireys earlier experience with concrete housing. He had designed and used the Airey Duo slab system in the 1920’s. In common with some other concrete house designs of the period. The 1940’s Airey house (Dubbed the new improved duo slab) was intended to use the minimum amount of imported material and be erected with minimal use of heavy plant, using unskilled labour from the depleted labour sources of the time.
The Airey house structure consists of precast concrete, storey height columns clad with concrete panels in a ship-lap arrangement. Columns are at 18″ centres and panels are 3’0″ long and about 1 1″ high. They are attached to the columns by loops of twisted copper wire which pass from hooks on the rear face of the ends of the panels, behind the adjoining columns to similar hooks on the adjoining panels. Columns are exposed in the window openings where they serve as mullions and reveals.
The critical element of the design, is the columns. They are exceptionally slender and are reinforced with steel tube, rather than bar reinforcement. The reinforcement tube extends to the ends of the columns.
Jigs with projecting prongs were used to locate the columns during construction. The ground, first floor and roof structure columns were dowelled together. However, columns with steel tube exposed at the end were stood on a damp proof course to form the ground floor walls.
With no cavity insulation and cladding that was not reliably weather-proof, water has been found to condense in the cavity, or enter through driving rain causing it to accumulate around the column feet, causing corrosion of the reinforcing tube.
A further factor leading to decay, is the small dimension of the column section, approximately 2″ by 4″. The tube is 1″ external diameter, so there is very little concrete protecting the steel. The thin gauge concrete was made with small aggregate which has a higher water demand than standard concrete. Consequently, the tube reinforcing an Airey column is liable to rust, both where it is in contact with any water on the DPC and at any point in its height where carbon dioxide has neutralised the alkalis in the thin concrete covering.
Foundations: Typically, the substructure consists of a concrete strip foundation supporting a 9″ brickwork wall. Alternatively, a mass fill concrete foundation may be used.
Internal Walls: Internally, the columns are usually clad with either fibreboard or plasterboard, secured to a timber fillet cast into the back of the columns. However, Airey properties are occasionally found to have a block work lining.
Floors: The ground floor is of solid concrete construction. First floor joists are sometimes timber, but are more commonly fabricated beams akin to was then known as the Metsec form. These span from front to rear over a spine wall structure.
Roof: Roofs are traditional pitched timber rafter/purlin construction, with a plain gable. The main roof is clad with either interlocking or plain tiles on felt and battens. Gable apexes are typically clad with plain tiles, although timber or PVCU boarding is occasionally used.Gable pikes are tile hung or timber clad. The Airey house type is susceptible to column reinforcement corrosion which can cause the columns to split in two.
- The party wall comprises similar columns to those used for the facade, clad with plain panels.
- The wall consists of two leaves similar to the outer wall placed back to back. The internal spine wall (running parallel to the front elevation) is of concrete columns with plasterboard lining.
- At eaves level, this construction ceases, and the roof space party wall is formed from either 4 1/2″ brickwork or 3″ clinker blockwork.
- The load bearing spine wall partition to the ground and first floor consists of similar prc columns to those used for the facade. Non-load bearing partitions are formed from timber stud framing.
- Partitions are lined with either plasterboard or fibreboard, as are the ceilings.
- The chimneys are of masonry construction.
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