Preservation of historic buildings

Much time and effort is devoted to the development of schemes for the preservation of historic buildings, but sometimes it seems that scaffolding and temporary works, the means by which conservation schemes are successfully completed, receive little attention. If they are not erected correctly and with due care and attention to detail, these works can cause great damage to the historical fabric.

The basic processes of design and assembly of scaffolding and temporary works in a historic building are not very different from those needed when any other existing building is affected. The purpose of this article is to highlight some of the important points that require special attention if you want to avoid damage to the historical fabric.

With regard to non-historic buildings, damage caused by poorly constructed scaffolding and temporary works, despite being strenuous and causing unnecessary costs, can often be repaired without serious damage. As far as the historical fabric is concerned, any damage is permanent and significant details can be lost. Once healed, an important facade is marked forever.

All badly erected shoring work, whether or not for a building of historical importance, has the potential to allow the collapse of part of the building with disastrous and possibly fatal consequences. Experience indicates that when things go wrong, it is usually due to a lack of attention to seemingly minor details.

Scaffolding and temporary works must be able to be constructed without the need for an important intervention in the historical fabric. This must be taken into account by the designers and builders of scaffolding and temporary works.

ACCESS SCAFFOLDS

Normally "independent tied" scaffolds will be provided for painting, signaling or other maintenance work. They consist of two rows of standards (the vertical supports) connected by accounting books and crossbars (the horizontal elements). The "independent" scaffolds are not exactly what their name suggests. They are called "independent" because they do not obtain vertical support from the building and "tied" because they must be tied to the building to achieve horizontal stability. Due to the need to avoid damage, tying scaffolding to the facade of historic buildings can sometimes present difficult problems. Sometimes, if the historic building is fragile, it will not be able to provide the horizontal restriction needed by the scaffolding and this must be achieved in other ways, such as by providing external scaffolding abutments or by attaching the external scaffolding to a cage frame. internal birds scaffolding.

The 'Putlog scaffolds', used for the construction of brick walls, have a single row of standards that are usually erected about 900 mm from the face of the wall, with the boards in the horizontal members known as 'putlogs'. When used in new constructions, the flattened ends of the retention logs are incorporated into the bed joints as work progresses and then removed once completed, pointing up the resulting orifice. (The square holes of 100 mm used for wooden putlogs can sometimes be found in medieval works). Putlog scaffolds should not be used in historical construction work, as unnecessary damage is caused by cutting holes in the putlog bearings.

SHORING OR SUPPORT SUPPORT

Temporary jobs are often necessary either because there is a risk that a structure collapses or because it is necessary to remove some life support member for renovation or alteration. The loads that must be transported by shoring can be very large and the danger posed by bystanders and weaving by an inappropriate design should never be underestimated.

The main difficulty in propping up historic buildings is to ensure that their installation does not cause damage. Shoring must be designed by a structural engineer or other competent person.

DESIGN

The scaffolding design should not, unless it is very simple, be left to the erector of scaffolds. It is important that attention be paid to the location of scaffolding foundations, where standards can and can not go and where decks with tables are required to allow work to proceed with as little difficulty and risk as possible.

All temporary works must be designed before site personnel begin to be constructed, and the level of design and design of the scaffolds and temporary works must be in accordance with the scale of the works. A pencil drawing on a sheet of paper may be enough, indicating that at least someone has thought about what is needed before the work begins. A larger job may well demand proper calculations and drawings.

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