On-site inspection of wooden structure

Procedure and applications

 

Church of Nativity in BETHLEHEM (2013-2015)

International Restoration Project – Constructor: Piacenti SpA

Prior to drawing the working plan of structural restoration works, a detailed diagnostic survey of the wooden structures of the roofing and interior entablature was carried out in two different periods of time. The inspections were performed with the standard procedure, in compliance with the Italian technical standard UNI 11119:2004, which provides for an accurate visual inspection at a close distance of all portions of the structures, combined with the execution of “on-site” non-destructive tests. In particular, the inspection included a detailed relief of the structures (joints, sections, etc, also when not exposed), identifying the wood types, grading their mechanical quality, detecting any existing degradation. The survey helped highlight all the technological characteristics of both structures and wood essences that are required to plan static verifications in a rigorous and reliable way, as well as detect any degradation conditions – both evident and hidden – whose thorough understanding was needed to set up a convenient plan of interventions, which were subsequently planned and executed. (figures 1-16)

 

COMPLEMENTARY DIAGNOSTIC METHODS TO LOCALIZE HIDDEN WOOD ELEMENTS

The conservation of historical buildings is based on increasingly more detailed analyses of the construction characteristics of architectural structures. The historical research conducted on 2 out of 12 colonial churches erected in the centre of Santiago in Cuba revealed that wooden elements are hidden inside masonry or beneath plaster. Instrumental verifications were carried out with a special layout of sonic transparency testing (simplified tomography), which was based on testing orthogonal/crossing trajectories to detect any discontinuity in the section of masonry pillars owed to the presence of wooden trunks. With a view to calibrating the method accurately, limited videoendoscopic inspections were executed in pillars based on the results obtained from the sonic testing campaign.
The hidden wooden structures lying beneath plaster were inspected with a thermographic method, by taking advantage of both high ambient temperature and the different thermophysical properties of wood as compared to masonry. (figures 17-23)

 

Former Hospital S.Agostino MODENA (2013)

Constructor: Candini Arte srl

The survey was executed in the framework of a restoration project of a former hospital with a view to changing its destination of usage. All existing wooden structures were inspected, including floors and roofing, either exposed or hidden, by identifying their type and main characteristics.  Some detailed local analyses were carried out to grade the technical characteristics of the wood and its state of conservation, including “on-site” non-destructive testing (resistograph method). The survey helped supply a general outlook of the conditions of the structure in terms of wood types, their amount and distribution, general and particular conditions of conservation.  All the information supplied was useful to make design choices and draw a working plan. (figures 24-31)

 

[by Massimo Mannucci and Riccardo De Ponti]