POST WAR AIREY HOUSES

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GENERAL INFORMATION ON CONSTRUCTION South Cambridgeshire District Council 61 72 -Investigation of Non-Traditional Concrete and Timber Framed Propertr'es Structural Survey Report -5 CONSTRUCTION DETAILS 5.1 Addison Houses 5.1.1 Introduction The Building Research Establishment (BRE) were unable to provide any information concerning this particular system type, although it is believed the properties in the South Cambridgeshire District were erected in 1921-1922. Despite extensive experience of non- traditional housing systems, this is not a construction type previously known to MDAL. 5.1.2 Foundations The substructure consists of concrete strip foundations supporting a course of blocks laid flat, similar to modem day trench blocks. 5.1.3 External Walls External walls are of cavity wall construction, comprising two leaves of 4" concrete blockwork, laid stretcher bond, separated by a 2" uninsulated cavity. They are lined internally with fibreboard. Brickwork quoin coursing is incorporated to the corners of the building and an 18" wide brickwork pier is built either side of the fiont door opening. A 'band' course, formed by a projecting course of blockwork, is introduced at first floor level, with pre-cast concrete lintels incorporated over window and door openings. 5.1.4 Floors The ground floor is of solid concrete construction, whilst the first floor is of timber construction. 5.1.5 Roof The roof is a traditional timber rafierlpurlin structure, with a king post truss arrangement. The roof is clad with interlocking tiles on felt and battens. 5.1.6 Other The party wall is believed to be of cavity wall construction similar to the external walls. The chimneys and internal partitions are also built in blockwork. Ceilings are formed with fibreboard. Page 13 of 48File RefiA 6000161 721Repo~1R001 AS 06-12-99 South Cambridgeshire District Council 61 72 -Investigation of Non-Traditional Concrete and Timber Framed Properties Structural SU& ~eport 5.2 Airey Houses 5.2.1 Introduction The design was developed by Leeds-based builder Sir Edwin Airey in the aftermath of the Second World War, and built on Airey's earlier experience with concrete housing. He had designed and used the Airey Duoslab system in the 1920's. In common with some other concrete house designs of the period, the 1940's Airey house was intended to use the minimum of imported material and to be erected with minimal plant using unskilled labour. 5.2.2 Foundations Typically, the substructure consists of a concrete strip foundation supporting a 9" brickwork wall. Alternatively, a mass fill concrete foundation may be used. 5.2.3 External Walls Airey house structures consist 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 11" high. They are attached to the columns by loops of twisted copper wire which pass fiom 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. These 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 columns during construction, and ground and first floor columns were doweled together, as were first floor columns and the roof structure. 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, any water condensing in the cavity, or being driven in fiom outside, could accumulate around the column feet with inevitable corrosion of the reinforcing tube. A fbrther 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 little concrete cover protecting the steel and that must be made with small aggregate with an inevitably higher water demand than normal. 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 cover to the steel. 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 blockwork lining. Page 14 of 48File RefiA 6000\6172\Reports\R001 AS 06-12-99 4 South Cambridgeshire District Council I 61 72 -Investigation of Non-Traditional Concrete and Timber Framed Properties i i Structural ~uhey Report -.--5.2.4 Floors The ground floor is of solid concrete construction. First floor joists are sometimes timber, but are more commonly fabricated beams akin to the modem Metsec range. These span from fiont to rear over a spine wall structure. 5.2.5 Roof Roofs are traditional pitched timber rafier/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. 5.2.6 Other The party wall comprises similar columns to those used for the facade, clad with plain panels. At eaves level, this construction ceases, and the roofspace party wall is formed fiom either 4%" brickwork or 3" clinker blockwork. The loadbearing spine wall partition to the ground and first floor consists of similar prc columns to those used for the facade. Non-loadbearing partitions are formed fiom timber stud framing. Partitions are lined with either plasterboard or fibreboard, as are the ceilings. The chimneys are of masonry construction. 5.3 Hawksley BL8 Bungalows 5.3.1 Introduction Hawklsey BL8 aluminium bungalows were designed by a body called the Aircraft Industry Research On Housing. Those at Duxford and Sawston were erected in 195 1. 5.3.2 Foundations Typically, the foundations comprise a concrete raft, thickened at the edges. Occasionally though, concrete strip footings supporting a 9" brickwork wall form the substructure. 5.3.3 External Walls External walls comprise pre-fabricated wall panels, 12'0" long x 8'0" wide, which were brought to site and bolted together. The panels consist of corrugated aluminium outer sheeting, with building paper on the rear. The sheets are fixed to a timber framing comprising 1%'' x 2%'' timber studs and noggings. There is approximately 2" thick mineral wool insulation between the studs, and the panels are lined internally with plasterboard. Around the perimeter of the panels, aluminium channel sections are located. Channels of adjacent wall panels are bolted together by 3 Nr aluminium U-shaped brackets. Page 15 of 48File Refin 60001 61 72lReportsl ROO1 AS 06-1 2-99 South Cambridgeshire District Council 61 72 -Znvestigafrafronof Nun-Traditional Concrete and Timber Framed Properties structural SU& ~&ort -5.3.4 Floor The floor is of solid concrete construction. 5.3.5 Roof The roof consists of timber trusses, onto which span timber purlins supporting an aluminium profiled roof sheeting. Purlins are connected to the trusses by means of aluminium U-brackets, nailed to the trusses and screwed through the purlins. A fibreboard lining, approximately '18" thick, lines the underside of the roof sheeting. Timber joists span between the trusses, and act as fixing points for the ceiling finish. 5.3.6 Other The party wall consists of similar wall panels used for the external walls, and is lined with plasterboard. Typically, partitions are also a panel construction and comprise timber studding with an aluminium channel section around the perimeter. Occasionally, timber stud or paramount board partitions may be used. Both partition walls and ceilings are lined with plasterboard. The chimney is of masonry construction. 5.4 Industrial Properties 5.4.1 Introduction The properties at Fulbourn are believed to be Bison large panel system type dwellings. The Bison system is based upon large storey height precast reinforced concrete panels, with in-situ concrete joints at the junctions of the panels and floor units. The in-situ joints contain steel reinforcement, which tie the panels together and provide continuity to the structure. The first Bison system dwellings were erected in 1963 and over the years three basic systems evolved, these being the Bison Wall Frame, Bison Crosswall and Bison Preferred Dimension Frame. The properties in question appear to be the Bison Wall Frame type. 5.4.2 Foundations The foundations consist of a concrete strip footing supporting a concrete ground beam. 5.4.3 External Walls The Bison Wall Frame system comprises loadbearing storey height precast reinforced concrete (prc) flank-wall and cross-wall panels. The prc floor units of the next storey then bear on the top edge of the panels, with an in-situ concrete joint made at the junction of the panel and floor unit. Page 16 of 48File RefiA6000I 61 72\Reports\R001 AS 06-1 2-99 -, -~ *p, South Cambridgeshire District Council 6172 -Investigation of Nun-Traditional Concrete and Timber Framed Properties Structural Survey Report Steel dowels, which project from the lower panels, are used to locate and position the panels for the next storey. Non loadbearing panels, referred to as fascia units, are typically used to clad the front and rear elevations. These are of sandwich construction, comprising two leaves of reinforced concrete separated by a 1" layer of expanded polystyrene. Stainless steel ties were usually used to connect the two leaves together. The Bison Wall Frame system allows for walls, other than the cross and flank walls, to be finished in a variety of materials other than concrete. Thus, on some variants, timber or PVCu boarding is used to clad part of the dwellings. The vertical joints of the external wall panels are grooved to locate weatherproofing strips in the outer leaves, whilst the inner leaves are rebated to enable overlapping of reinforcement of , adjacent units within the in-situ concrete joint. Internally, the walls are dry lined with a plasterboard finish. 5.4.4 Floors The ground floor is of solid concrete construction. The first floor consists of a series of prc units laid alongside each other, which bear upon the gable and party walls. 5.4.5 Roof A concrete flat roof construction has been utilised, with an asphalt covering, laid to falls. 5.4.6 Other Partitions consist of timber stud framing lined with plasterboard, whilst ceilings have a hard plasteredlartexed finish direct to the underside of the concrete floor. 5.5 Swedish Timber Properties 5.5.1 Introduction Following a war-time purchasing commission visit to Sweden, Swedish Timber dwellings were imported into the United Kingdom fiom 1945 onwards. The prefabricated sections were subsequently erected by contractors working for the Ministries of Health & Works and the Scottish Department of Health. It is estimated that approximately 4500 dwellings in total were erected. 5.5.2 Foundations Typically, the substructure consists of concrete strip foundations supporting a 9" brickwork perimeter wall and 9" and 4%" brickwork honeycomb internal support 'walls. Air bricks are located within the perimeter walls to provide ventilation beneath the suspended ground floor. Page 17 of 48File Refill 60001 61 72lReportslR001 AS 06-12-99 South Cambridgeshire District Council 6172-Investigation of Non-Traditional Concrete and Timber Framed Properties Structural Survey Report A bituminous felt or asphalt dpc is laid along the perimeter and internal walls. Typically, the oversite cover is concrete. 5.5.3 External Walls External walls consist of storey height timber frame panels nailed together. The panels comprise 2" x 5" or 2" x 3" timber studs, spaced at centres of up to 4'-9",the 2" dimension being normal to the plane of the wall. The panels contain horizontal timber noggings and, in some instances, timber diagonal braces. Internally, the panels are clad with 3" x 7/s" tongue and groove vertical boarding, with a building paper backing. The boarding is then faced with '/s" fibreboard or hardboard. Externally, the panels are clad with half checked and channelled 3" x 7/s" vertical timber boarding, nailed to the studwork over a bituminous building paper breather membrane. Fibreboard insulation, %" thick, is provided between the panel frame studs, with the bottom rails of the panels fixed to a separate timber soleplate laid on top of the damp proof course. 5.5.4 Floors The ground floor is suspended, consisting of 5" x 2" timber joists spaced at 18" centres, finished with 7/8" tongue and groove timber boarding. The joists span between the front and rear walls, with intermediate support provided by brick internal support walls. The joists are notched and bear onto both the timber sole plate and the dpc laid on the substructure brickwork. The single storey attached outbuilding has solid concrete floor construction. The first floor comprises 8" x 2" timber joists, spaced at 18" centres, finished with 5 x 7/s" tongue and groove timber boarding. The joists span between the front and rear walls, with intermediate support provided by a ground floor timber stud partition spine wall, over which the joists are notched and nailed. The joists form part of the roof structure in the chalet bungalow variant, which has two dormer windows on the rear elevation. 5.5.5 Roof The roof comprises 6" x 2" timber rafters spaced at 3'0" centres, with 6" x 2" joists spaced at 18'' centres. The joists are notched over a 4" x 2" timber wallplate and are secured to the rafters via timber gusset plates. At approximately the centre of each rafter, a pair of 4" x 7/s" timber collars are located. The rafters are covered with 7/s" timber tongue and groove sarking boards over which bituminous roofing felt is laid. Timber battens are fixed on top of the felt and the roof is clad with either interlocking or plain tiles. Page 18 of 48File Refill 6000\ 61 721Reports\ ROO1 AS 061 2-99 < South Cambridgeshire District Council 61 72 -Investrgafiafionof Nun-Traditional Concrete and Timber Framed Properties Structural Survey Report 5.5.6 Other The party wall consists of 9" solid brickwork, plastered internally. Partitions consist of timber stud framing, clad on both sides with '18" tongue and groove vertical timber boarding and typically faced with fibreboard or plasterboard. Ceilings are formed with %'I fibreboard. The chimneys are of masonry construction. 5.6 Unity Properties 5.6.1 Introduction The Unity system was devised by architects Kendrick, Findlay and Partners. An early design was used for probably under 100 houses in the 1947-48 period, then a re-design was used to build possibly 3,000 houses between 1948 and 1950. A further re-design in 1950 was used for -the next 10 years to build the bulk of the 19,000 Unity dwellings constructed. The properties at Great Shelford are of the latter type and are classified as the 'B'type variant. 5.6.2 Foundations Foundations consist of a concrete strip footing. 5.6.3 External Walls The load bearing elements in a Unity house consist of storey height, reinforced concrete columns of 3%" x 6" cross section, at 3' 0" centres around the house perimeter. The earlier design has columns with an indentation in the sides, giving a dumb
AIREY HOUSES POST WAR