Chapter 2

Why do timber frames fail? 5/5.

2.7 Poor workmanship.

Poor workmanship is more likely later in the history of the house when poor quality alterations using second-rate (Fig. 2. 14) or second-hand materials was common. Poor workmanship here can be defined as the loss of the quality carpentry and joinery that typified the early fully jointed timber frames. From the 17th century even prestigious buildings suffered from the dilution of the trade as quality joinery gave way to the wholesale and often unskilled, hammering of wrought iron nails and spikes through ill selected timbers.

Poor workmanship in a timber frame

Fig. 2.14. An extreme example of low caste workmanship in Forge House at Castle Camps, Cambs. This pseudo-cruck constructed door frame with every scantling pinned in with wrought-iron nails gives an idea of the type of work prevalent from the early 1700's.

The nailed in timbers spring out or the fixings corrode leading to failure from disconnection. The timber sections can be too slight to bear the loads later required.

2.8 Structural redesign leading to weakening.

Often in the history of a house the building is remodelled to fit the fashion of the day. Thus mediaeval halls, once open to the roof with an open hearth in the floor, commonly will have an inserted firestack and first floor and then a garrett room with dormers. Doorways may be moved and new openings made. Almost certainly the window openings will be altered to accommodate sash and casement windows. The roof structure could be seriously altered, purlins cut, collars and crown posts removed and rebates cut into ties for door openings. (Fig 2.15).

Joist hangers and plate repairs

Fig 2.15. The Wheelwrights Cottage, Castle Camps, Cambs. The insertion of a floor with dormers into a thatched cottage which was probably originally a kitchen to a bigger house was potentially a disaster. Copious ironwork was amateurishly inserted to arrest its collapsing floors and splaying walls.

All these kind of destructive alterations where timber is removed or sections reduced require adequate bracing to prevent movement. Ironwork is often used at the time of alteration, or later, to check movement.

3.1 Origins of ironwork repairs

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