HISTORIC IRONWORK REPAIRS IN TIMBER-FRAMED BUILDINGS.

3. The Origins of Ironwork Repairs in Timber-framed Buildings. 2/2.

It is not possible to walk in an historic town or village centre without seeing the square brick and rendered facades of timber buildings whose hidden presence is so obviously given away by their steep pitched roofs with undulating ridges (Fig. 3.6).

Stripped facade reveals a low quality frame

Fig. 3.6. The striking fašade of 25 High Street, Thaxted, Essex. The poor quality timber-frame with its multitude of alterations was not meant to be seen. The building would have been rendered with lime plaster, like its neighbours, in imitation of stone. The Georgian sash windows would then have sat more comfortably in its neo-classic street frontage and only the peg-tiled roof would have betrayed its earlier origins.

Many jettied buildings were under-built to create flush facades and it must have become rapidly evident that by removing the integrity of the frame, movement and subsidence would follow. Tailor-made and off-the-shelf ironwork (Fig. 3.7) offered a quick, cheap and unobtrusive method of pinning and reinforcing failing and removed joints without the expense of wholesale dismantling.

L-tie holds the joist in place

Fig. 3.7. One of a series of wrought-iron L-ties in Oak Cottage, Great Yeldham, Essex. The front wall was removed when the jetty was under-built and the new one reinforced with iron. The line of the original bressummer is delineated by the white bleaching of the joists.


The infill of the panels was frequently changed from wattle and daub to brick nogging or flint coursing and the increased weight shifted and contorted the frames causing the walls to fall outwards and pull at their tie beams. Wrought iron tie bars were inserted to prevent the building bulging out at their floor levels and eaves. (Fig. 3.8).

Nailed on tie-rod stabilises failing walls

Fig 3.8. A nailed in tie rod in a cottage in Rattlesden, Suffolk. The original wattle and daub infill has been removed and replaced with brick nogging. The increased weight bulged out the wall which then had to be tied to the main spine beam. This is an early Victorian alteration and the tie rod is circular in section. The present owners have compounded the problem by removing the internal lath and plaster which was stabilising the frame.

Ironically, those buildings that were rendered with plaster and ruled to look like stone probably suffered far less. Although the render is heavy it resisted penetration by water and the lath-work encased the building in a flexible armature that restrained movement thus combating the two most likely causes of timber failure: stress and decay.

As time progressed the heavy oak timbers beloved of the quality carpenter became scarcer and elm was used in its stead especially to insert new floors. The carpenters began to realise that thinner section timber could be used and that if it were of rectangular section not only was it stronger and lighter but considerably cheaper. By the 1700's trusses were being assembled with gang plates in new work and elements were being bolted together.

In 1759, Price wrote in his British Carpenter; 'There is one particular that had liked to escape my notice, concerning the placing of iron straps on any truss, thereby meaning to help its strength, which is by turning the end square.' In describing the simple L-tie, Price points the way to wholesale construction and repair in iron.

When softwoods like pine started to be used in great quantities in house building at the end of the C18th the sections became thinner still and frames were reduced to skeletal elements simply pinned together with nails. The reduced sections made jointing impracticable as there was no longer enough material to create a structurally solid mortice and tenon and so platework fully emerged. Nailed and bolted gang plates, stirrups and tensions bars, hangers and U-clamps were rapidly designed into new buildings incorporating innovations such as the composite beam (Fig. 3.9).

Composite beams in the Builder Magazine

Fig. 3.9. A plate from The Builder of 1848 p495 showing a composite beam in Middesex Hospital. The oak elements are stressed with wrought iron tie bars.

Inserted work was now being jointed in and reinforced with off-the-peg iron straps and ties. For example, at Hylands House, Chelmsford, Sir Humphrey Repton remodelled the brick house of Queen Anne style to incorporate two storey-height bay windows with new floors each tied in with identical straps and hangers to the original fully jointed oak beamed floor and the new four piece composite tie-beams.

The house (Fig. 3.10) built c1730 by Sir John Comyns was 'altered out of all recognition' by 1815 when it was sold on and in 1839 it was taken by John Attwood. An 'iron master', he replaced timber wholesale with cast-iron I-beams, replaced carpentry with nuts and bolts and nailed his slender joists in with wrought iron clouts. (Abraham. E 1988).

Hylands was remodelled using wrought iron

Fig 3.10. Phase plans of Hylands House prepared by Esmond Abraham. All the post 1797 work was achieved by tying the timber elements together with bespoke wrought-iron ties. In 1842 the house was remodelled using wrought-iron I-beams.

In his book The Carpenter's Assistant 1857-60, J Newlands illustrates the plethora of mass-produced plates and iron-ties (Fig. 3.11) for the construction of trusses and the like. The age of constructional ironwork in timber buildings had arrived.

Off the peg ironwork joints

Fig. 3.11. A plate from J Newlands book The Carpenters Assistant of 1857-60 showing the comprehensive array of off-the-shelf ironmongery used in Victorian timber construction. Illustrated are bolts, stirrups, gibs and cotters, U-clamps and tie-rods.

4.1 Historic Availability, Characteristics and Use of Wrought Iron.

 

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