- Manufacturer: Cruden Homes Ltd
- Type: Steel Frame
- Period Built: 1947-1950
- AKA: Cruden Rural
- Number Built: 3,000
Cruden House background information.
In the post-war years a group of skilled contractors joined forces to form Cruden Houses Limited.
In 1946, the company submitted plans to build the steel framed Cruden Rural House to the Inter-departmental Committee on House Construction (the Burt Committee), in response to the Governments non-traditional house building programme
The newly formed company, Cruden Houses Limited was formed through the joint collaboration of the following contractors;
- Cruden Limited, Musselburgh
- A Hall and Son, Aberdeen
- The Alliance Construction Company, Dundee
- J Wright and Company, Edinburgh
- J Laidlaw and Son, Glasgow
Cruden dwellings are of semi-detached or terraced construction, with pitched roofs but some flats were also constructed from this design. The houses incorporated a light-weight cold-rolled steel frame, clad externally in concrete blockwork with each blocks being 3ft 6in long by 9 7/8 inch high.
In general, the external concrete blockwork was given a protective coat of paint but in Scotland, the properties were generally rendered to provide extra protection from the harsh elements.
Cement was scarce in the 1940’s post-war years which lead certain local authorities to substitute 4 1/2 inch bricks for the concrete cladding. Although identical in every aspect to the Cruden Rural House, apart from the brick cladding, this adapted version became known as The Cruden Brick-clad house.
Over 3,000 of these properties were constructed in Scotland between 1947 and 1950.
The very first prototype of the Cruden house was erected near Milton Road Edinburgh. At this time, the new Temporary housing programme was in full swing. Plasterboard and asbestos cement roofing tiles were suddenly in short supply as the majority of these materials had been swallowed up by the Temporary Housing Programme in its attempt to mass produce homes quickly and cheaply. Cruden were thus forced to use fibreboard instead of plasterboard for wall linings and heavy concrete roof tiles, in place of tiles made from asbestos cement.
The steel framed Cruden House, also commonly known as the Cruden Rural or Cruden Brick-clad, were typically constructed as 2-storey semi-detached and terraced houses. These dwellings were typically built containing 4-apartments with two-storey semi-detached or terraced houses.
Minor variations in the layout and general construction of these homes do exist. Shortages of certain materials would sometimes lead to the adoption of alternatives in order to achieve the desired outcome, but in all cases, the integrity of the structural framework remained unchanged. A number of flats were also built to this form.
Surveyors Notes: The following issues have been noted during investigation into a number of these properties.
- Severe corrosion of cold RSC stanchions (Frame Legs), particularly at bases.
- Corrosion of beam and stanchion connections at first floor level.
- Corrosion of horizontal sill members.
- Bowing of the external concrete block walls has been noted.
- Cracking to exterior render and external walling.
- Cracking and spalling of concrete blocks has been noted at and around windows.
Foundation was of concrete strip footings and a Precast Concrete underbuilding of nine-inch thick precast or cast in situ concrete walls and honeycomb sleeper walls built from concrete blocks.
The solum (soil layer) is covered with 3 inch ashes and finished with 2 layers bitumen emulsion. A bituminous felt dpc was then placed on top of the foundation walls.
The frame consists of:
- 24 cold Rolled Steel Channel stanchions (RSC) (per single storey).
- 4 cold Rolled Steel Angle (RSA) lateral perimeter ties.
- 8 cold Rolled Steel Channel (RSC) floor support beams, cold Rolled Steel Angle (RSA) sills.
- 8 cold Rolled Steel Channel (RSC) trusses and cold Rolled Steel Angle purlins, see frame layout below.
The frame stanchions are located at 3ft 6in centres, situated within the external walls and rag-bolted to the foundation. They extend upward to the roof line of the building.
At first floor, cold-rolled steel channel beams span between the front and rear elevation. They are connected by three bolts to steel plates welded to each stanchion. Some of the beams are propped mid-span by single-storey cold·rolled, steel lipped channel stanchions.
At eaves level, stanchions to the front and rear elevation are tied laterally by steel angles.
Steel roof trusses span between the front and rear elevation, and are bolted to the head of each stanchion. Each rafter member and ceiling joist consists of two steel angles.
At corners, the two adjoining stanchions are connected by angle cleats welded to both stanchions. Diagonal bracing straps extend from the bottom of the corner stanchion to the first-floor level of the adjacent stanchion on each elevation.
Similar diagonal bracing extends from each of the stanchions at the separating wall to the adjacent stanchion in the same dwelling within each pair.
For a more in depth description including frame components sizes, readers are encouraged to purchase the following report from the BRE website.
The steel frame was generally protected with a layer of Zinc-chrome paint to reduce the risk of corrosion.
External walls: Constructed from harled Precast Reinforced Concrete blocks.
Harling (or roughcasting) was originally applied to rough stone walls to protect them from the Scottish weather. It consisted of lime mortar mixed with small stones or shells being hurled or cast against the wall and produced a rough textured finish. Lime wash would sometimes be applied every few years to help seal small cracks.
Between the block walls there is a cavity followed by timber framework which was backed with building paper, before being lined with fibreboard and plasterboard. A type of Glass-fibre insulation was inserted between the timber studs.
Separating wall: Having a PRC block cavity wall also lined with timber
framing and backed with building paper, fibreboard and
plasterboard. Glass-fibre insulation inserted between frame studs.
Partitions: Are of timber stud lined with plasterboard.
Ground floor: PRC slabs on Precast Concrete block, dwarf walls.
First floor: Tongue & Groove boarding onto timber joists mounted across steel beams.
Ceilings: Fibreboard and plasterboard on timber framing.
Roof: Bituminous felt, timber battens and interlocking concrete tiles. PS eaves fascia, soffit and bargeboards.
Misc: A Flat or sloping canopy was often fitted over front door.
Variants of this build
- A concrete underbuilding.
- Harled brick used for external walls.
- Painted concrete block used for external walls.
- A suspended timber or concrete ground floor.
- Black bituminous paint was sometimes used to provide a protective coating to the steel frame.
GENERAL COMMENT ON CONDITION
The Building Research Establishment examined a number of Cruden Rural houses in Scotland and found that some properties were in their original condition whilst others had suffered from corrosion ranging from mild to severe.
The extent of deterioration varied considerably from house-to-house and site-to-site. In most instances some deterioration of the frame was noted whilst in others severe corrosion was found. The BRE advises that the full scale of corrosion, if present, can only be determined undertaking a full structural survey. However, in general, when a sample group of adjacent or nearby houses is being investigated, this may give a general representation as to the likely overall condition it should be possible to determine the general overall condition of the selected group.
Fortunately, as with all steel-framed houses, any deterioration to the frame or stanchions can be cut away and replaced very effectively.
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