2. Structural Systems
The archaic “Capanna italica” (the Italic hut), of which several specimens were found in the territory of the Lazio area, is already completely defined in its every element; the related Latin terminology is also a well articulated system (see Tampone, 1996, cit., for further references).

3. Characteristics
The search for minimization of the size of the members is a peculiar feature of the Italian wooden carpentries, i.e. for maximum span, maximum bay available with current sizes of the members section; the limit was given by the deformability of the members; for instance, the deformability of the rafters of the trusses or of the purlins which cover a bay.
An other important feature is the clarity of the hierarchy between members and structural units; the whole structural system in a hip-roof, for instance, is composed by the trusses and their members, the auxiliary beams which connect the trusses, the joists and the small rulers; all these elements are clearly connected in a definite, steady, stiff mechanism designed to carry itself and the external loads.
Resulting characteristics are evidence of the role played by every single member and the position of crisis sections showed by excessive deformations or cracks.
The inconvenience of this attitude, often, has been the formation in the time of structural failures, which made the already existing structural systems more interesting and gave the Designers of load bearing mechanisms strong hints and clear indications for the improvement of the engineering side of the question, that means structural evolution.
In the Italian specimens, auxiliary beams such as purlins, ridge of the roof etc. of a rectangular shaped section are, in the majority of the cases, correctly seating on their narrower side to offer the maximum flexural strength; but instances of members lying flat on the supports (North East regions, for instance; may be to reduce the covering’s height) are not rare.
The criterion of geometric harmony and metrical proportionality given by Vitruvius for the dimensioning of the members, namely the lintels, belonged to the context of the architectural order; Vincenzo Scamozzi, the Palladio’s Pupil, on the contrary gave an empiric formula for the dimensioning of the beams where the main factor is the span, i.e. the distance between the supports: the base of a beam should be from 1/24 to 1/30 of the length. He adds that the Egyptian triangle, 3, 4, 5, gives the best proportions between width and depth of the beam, i.e. 0,75 x 1.
In this regard, the principal members of the existing carpentries are in general well proportioned, and rather common is the ratio of around 0,7 (base): 1, which corresponds to the most rational use of a shaft and, roughly, to the golden section ratio (0,618). By the way, a similar ratio has been used in the Saint Catherine trusses dimensioning of the squared rafters, 1,17 x 22,5 cm, i.e. 0,77 x 1; here the slope is influenced by the abundant snow which falls in the region during the winter.
Research on proportions of the relations between acting forces and dimensions, configurations etc. is strictly connected to the search for larger spans, wider bays. This is evident if we compare the St Catherine Church in the Sinai, where trusses are very close each other and instead of purlins to support joists and boarding, a dense sequence of small joists bears directly the boards, with later arrangements such as Saint Mark’s church covering (XIV c.) in Florence where the span of the trusses is much wider: this important result is made possible by the use of intermediate members, the purlins. An aesthetic criterion is also to be recognized in the St. Mark’s and similar, because the articulation of the hierarchy is rendered more eloquent.
As for the aesthetics, the ancient carpentries were carefully shaped and the members were very regularly dressed, because they were part of the architecture and also very important from a religious and symbolic point of view; they were supposed to be seen from the ground and appreciated also as simple construction items. Workers were proud of their work, of the proportions and the geometry and of the articulation of the carpentries they made.
In the wooden works which were not intended to be in sight, in general, the members, for economical reasons, are squared for half of the height, from the base on, and simply rounded from the half up to the upper end (beams of the type “uso Trieste” or similar). In the trusses the good rule is to put the squared part connected with the tie beam. Mistakenly, sometimes we find the opposite positioning; in the floors the rule was to alternate the sense of the taping in the sequence of the beams.
An exception is certainly the XVIII c. roof carpentry of the central Hall of the Archaeological Museum of Naples, made of very rough logs of very poor quality (which in any case still exist and perform well…).
Very often these wooden carpentries were decorated with carvings, tempera paintings etc., gilded layers, moulds, stuccoes; geometric patterns were often inspired by heraldic themes. In the unique case (XV c.?) of San Niccolò di Nicosia, Sicily, decorations are real figural paintings conceived to show scenes of life with representation of characters, mythological figures, animals, plants, flowers etc.
Indeed, a very large number of wooden ceilings carry decorations.
The “tarsia lignea ” (wooden inlay), often representing the ideal solid bodies of the Platonic philosophy, architectures and nice landscapes in the perspective, found excellent expressions especially in the Renaissance; several famous Artists made cartons for the artisans of this speciality. Jacopo da Lendinara is one of the most celebrated Maestri.
The “Legnaiolo” was, in the Middle Age and in the Renaissance, a maker who was at the same time an architect, a maquette maker, a cabinet designer or maker, an artisan etc.; or even a timber dealer or a contractor. No wonder therefore that even the furniture pieces were conceived in the same unitarian way and that their conception followed architectural lines.

4. SPECIMENS

4.1 Genera
Botanic genera for timber were essentially Fir, Cypress, Larch, Chestnut (Poplar, Oak, Walnut, Helm to a lesser extent). In Tuscany the Opera del Duomo (as in many other Italian cities) also acted as a contractor for public works and timber dealer. The timber (white fir mainly) was taken from the forests of Vallombrosa, the state demesne, between Florence and Arezzo.

4.2. Surviving structures
An high number of very old, very interesting timberworks still survive in Italy; in many cases the original material or, at least, a large part of it was kept.

4.3. Built-up beams
A few examples of built-up beams of the kind described above are to be found mainly in the structural system of the floors and of the ceilings built since the Renaissance on (in Florence, Sala dei Gigli, Palazzo Vecchio; Sala di Carlo VIII, Palazzo Medici Riccardi etc.). A late example (end of the XIX c.) is the covering of the Ball Hall of the Palazzo Serristori, with two “Travate meccaniche” (complex built-up lattice beams) which contribute to the support of the underlying lathing vault; of the same period are the built-up beams which carry the false ceiling of the Ball Hall of the Demidoff Villa nearby of Florence.

4.5. Collar Ties
Very nice collar ties, of the Middle Age, are in the Torcello (Venice) cathedral, both in the longitudinal and trasversal direction.
“I Frari”, the Church of the Friars in Venice, has a splendid gothic wooden carpentry. Due to the settling of the soil, the Builders, in the Byzantine tradition, added aerial wooden tie beams at different levels, applied at the head of the capitals or so, in the two orthogonal directions, organized in a spatial system, for the purpose of connecting the opposite tall walls and to prevent their rotation. A similar device is found in St Mark’s Basilica in Venice, though in a less organic way.

4.6. Coverings
Many of the roofs of the Palladio’s buildings still survive; we chose one of them for our studies: the covering of the Villa Emo, in Fratta Polesine, which is conceived like the space-lattice of a crystal (Tampone, 2002)
Also present (XVIII c.) is an other type of covering for circular or square buildings, where the rafters are connected all together with a single kingpost and no chord; the rafters are stiffened by struts joined at the base of the central member. Peculiar in this sense are the late Stenditoio of the San Michele complex in Rome (now the grounds of the Italian ministry of cultural goods), a Church in Spoleto with similar arrangement, besides the “barchessoni” (circular one-storey constructions for the training of the colts) or the “casari” (plants for the production of the cheese), both found in the Emilia region.
Likewise, in the Liguria area, the coverings have large span and wide bays and the stiffness of the rafters is obtained by means of long struts supported by the walls, sometimes equipped with stone ancones, which provide an intermediate support.
A unique specimen is the covering of the St Agate Church, Scarperia, Florence, where the trusses of the central nave sit in turn on small wooden pillars supported by the stone columns which divide the hall in three naves, and on the ridge of the roof of longitudinal smaller trusses, giving rise to a very original spatial structural system.
As an example of the XVIII c. construction, I would like to single out the roof built on the central Hall of the XVI c. Palace which hosts the present Archaeological Museum (see before) in Naples; the covering system is composed of the higher order of trusses, shaped as stiffened Palladian trusses, covering a span of 25 m c.; the ceiling, an independent vault dressed in the Philibert de l’Orme technique, is also supported by a second order of trusses of almost similar stiffened palladian trusses, with a lower slope in comparison with the first.
The structural system of a few buildings of the XIX and beginning of the XX c. is based on the use of the “Polonceau” (also known as “Belgian”) trusses, invented by the Architect who bears the same name and presented in1839. Variants of this model can be found since the first invention up to today, with glue laminated rafters or similar.

4.7. Vaults and Domes
Domes with a wooden structure are rather rare and mainly to be found in the Veneto region (St Mark, St Rocco etc.).
The St Mark’s basilica domes, in Venice, are very peculiar. They are built, as said before, with meridian thin ribs; these are stiffened by parallel members circling the dome at different heights, by the outer boarding and by internal struts. “Restored” by Ferdinando Forlati in the Sixties, the St Mark’s specimens date from the beginning of the XIII c. and cover earlier masonry hemispheric domes the ceiling of which are decorated with the famous Renaissance gilded glass mosaics.
Similar domes were also built later in Venice: the wooden dome of the St. Rocco’s church, probably made in the XVII c., is one of them and also an earlier masonry dome; it has interesting features.
In Venice, Padua etc., in some of the churches of the XII and XIII c. the trusses carry a sheathing of perpendicular boards between the triangle formed by the rafters and the chord, arranged in shape of a longitudinal barrel vault which sometimes rests on similar vaults built on the ancones of the same trusses. Nice examples of these arrangements are to be found in the churches of San Jacomo all’Orio and Santo Stefano, both in Venice, in San Zeno in Verona, Eremitani in Padua and a few more; since they were the work of naval carpenters, they were conceived like up side down boats.
The roofs of San Zeno and Eremitani, badly damaged by the last war, have been largely restored.
Sebastiano Serlio introduced in Italy the “armamenti alla francese”; in any case, the system “invented” by Philibert de l’Orme (1561 his Treatize), to make lath vaults supported by ribs made of vertical boards joined together with nails, was soon introduced here; these vaults which were light, easy to build, adaptable to any shape, made of poor materials, very cheap, were extensively employed throughout Italy and uniquely applied in the construction of simple or elaborate ceilings. The reason is that it was possible to build them in every form and shape and this made them very suitable, much more than stone or brick vaults, for the complicated spatial arrangements designed by the Architects of the Baroque and following periods.

Frames, rather rare in the ancient times, have been used largely in the period of autarchy (the Twenties and Thirties of the last century, when Italy was hit by embargo) as a structural system to cover industrial plants, temporary pavilions etc., in the shape of triangular and arched ribs, transversal to the main axe of the building; the members of these frames are composed by small, almost costless, pieces of wood nicely arranged to give the maximum strength. Amongst the others, Adalberto Libera, Mario De Renzi, Giovanni Guerrini produced extremely interesting architectural expressions.

4.8. False ceilings
It is very interesting to note that in the mid- XVI c., when the interior appearance of the roof carpentry in the religious and civilian architecture started to be considered old fashioned, Architects were called upon to design false ceilings for many of the existing buildings; these added architectural elements, generally a wood imitations of the box ceilings of the classical stone element of the templar peristyles, of the vaults etc., were suspended, as a general and almost universal rule, to the tie beams of the trusses and not to the rafters; the consequences that one would expect from this erroneous bond, the deformation of the tie beam, the wrong functioning of the truss itself, a series of cracks etc., occurred in reality, especially when the trusses were not over-dimensioned.

5. Contemporaneity
Modern coverings or constructions are conceived with different structural systems and mainly with glue laminated beams or trusses; but a few of them are very innovative even from the point of view of the structural conception.
Some of them are inspired by the tree and the forest which are the primordial shelter of the human beings.
Renzo Piano planned the multifunction Centre in Noumea, New Caledonia, using Iroko timber for glue laminated ribs of half dome shaped pavilions, which are inspired by the silhouette of this tree: in this way, he was seeking a natural insertion of architecture into the wild landscape. The stability of the wood ribs, organized in two layers, is obtained by means of steel cross bracings and tenders, which actually are a secondary structural system along side of the principal one, co-operating with it.

6. Conservation
Care for this small but extremely varied and interesting heritage did not warrant much consideration until a few decades ago because the emphasis was placed on the outside aesthetic features of old buildings and on the interiors. Little or no attention was dedicated to the load bearing structures. Engineers are convinced that wood is a very perishable material. Therefore, when they deal with old wooden carpentries, for security and safety reasons, they generally tend to replace them, partially or completely, with other more fashionable materials such as reinforced concrete, steel, glue laminated wood etc. This trend must be changed from the grassroots level if we really want to save the material evidence of this ideal heritage.
For this purpose, it is essential to bear in mind that today it is possible to repair almost any kind of cracked structure with a minimum material sacrifice thanks to the fact that both specific and adequate techniques have been developed.
An interesting trend is the approach which tries to use mainly wood to repair wooden structural systems; but steel, which right from the beginning was a useful partner for wood, as well as today’s fibre reinforced composites (FRC) are increasingly being used thanks to the variety of available products of this type which are suited for every situation and which achieve a good level of performance in terms of resistance, service life, thermal qualities, reversibility etc.
Interesting restoration works have been achieved which can provide proof of this method and technology.

Bibliographical references:
Tampone G., 1983, Restauro delle strutture in legno, Congresso Nazionale “Legno nel Restauro e Restauro del Legno”, Proc. of the Conf., Palutan ed.: Milano
Tampone G., Trotta G., 1983, Legno nel restauro e restauro del legno. Catalogo della sezione espositiva, Giuntina Ed.: Firenze
Tampone G., 1985, Relazione generale al Congresso su: Legno nel Restauro e Restauro del Legno, in Boll. Ing., n° 3, Firenze
Tampone G., 1986, Wood and Architecture in the Renaissance, 19th Meeting of the Working Commission W-18 Timber Structures, International Council for Building Research Studies and Documentation 1986, Proc. of the Meeting, Dipt. di Ingegneria Civile dell’Università di Firenze,
Tampone G. (scientific editor), 1987, Atti del Congresso ”Legno nel Restauro e Restauro del Legno”, 2nd vol., Palutan ed.: Milano
Tampone G., Balenci P., Franci F., 1987, Legno ed architettura teatrale: il Teatro di Sarteano, Congr. Naz. sul Restauro del Legno, Firenze 1983, in Pr. 2nd vol.
Tampone G., 1989, Legno e Restauro, Catalogo della esposizione su Architetture e Manufatti Lignei, 2nd Congr. Naz. sul Restauro del Legno, Messaggerie Toscane ed.: Firenze,
Tampone G., 1989, Sostruzione e lamine metalliche per il consolidamento di una capriata lignea nella sala, di scherma della Fortezza da basso a Firenze, 2° Congr. Naz. “Restauro del Legno”, Firenze 1989, 1rst Vol. di Atti (a cura di G. Tampone), Nardini Ed.: Firenze
Tampone G., 1989, Restauro strutturale con lamine metalliche dei solai lignei della sede del Genio Civile a Firenze, 2nd Congr. Naz. “Restauro del Legno”, Firenze 1989, 1° vol. di Atti (a cura di G. Tampone), Nardini Ed.: Firenze
Tampone G., Campa L., 1989, Restauro strutturale con legno lamellare di un solaio e di una volta a carena lignei nell’Accademia di Belle Arti a Firenze (in coll. with 2° Congr. Naz. “Il restauro del Legno”, Firenze 1989, 1rst Vol. di Atti (a cura di G. Tampone), Nardini Ed.: Firenze
Tampone G., Franci F., Campa L., 1989, Rinforzo di puntoni e consolidamento di una capriata del teatro di Sarteano mediante centine metalliche 2° Congr. Naz. “Restauro del Legno”, Firenze 1989, 1rst vol. Proceedings (G. Tampone sc. ed.), Nardini Ed., Firenze
Tampone G., Pompucci M., Pesci C., 1990, Metodologia di prova di travi lignee rinforzate con lamine metalliche, 2° Congr. Naz. su “Il restauro del Legno”, Firenze 1989, 2nd Vol. Proc., Nardini Ed.: Firenze
Tampone G., 1989, Problematiche del restauro delle strutture lignee ed odierni criteri di intervento. Relazione generale al 2° Congr. Naz. “Il restauro del Legno”, Firenze 1989, 2nd Vol. Proc., Nardini Ed.: Firenze
Tampone G., Macina F., Rachello M., 1990, Bibliografia annotata sul restauro delle strutture lignee, 2° Congr. Naz. su “Il restauro del Legno”, Firenze 1989, in 2nd Vol. Proceedings, Nardini Ed.: Firenze
Tampone G., 1999, Restauro del legno, Atti del 2° Congr. Naz. “Il restauro del Legno”, Firenze 1989, Nardini Ed.: Firenze
Tampone G., 1992, Considerazioni sulla metodologia del restauro delle strutture di legno, in Progetto Legno, PEG Ribera ed.: Milano
Tampone G., 1994, Un brevetto per il consolidamento delle travi lignee inflesse mediante l’inserimento di lamine metalliche, 1994, in Boll. Ing., n. 7 – 8, 1994 Firenze
Tampone G., 1994, Restauro di cornicioni in legno, 1994, in Boll. Ing., n. 7 –8 1994, Firenze
Tampone G., 1995, Uso, controllo e manutenzione delle strutture portanti lignee degli edifici monumentali, in Proc. II Conv. naz. A.R.Co. “Manutenzione e recupero nella città storica”, Gangemi ed.: Roma
Tampone G., 1996, Il restauro delle strutture di legno, Hoepli: Milano
Tampone G., 1998, Degradacion estructural y restauracion de las estructuras portantes ligneas de los edificios monumentales, 1996, Sem. Int. « La conservacion de la madera en los edificios antiguos », 1996, Proc. (ed. by Liliana Palaia Perez), Universidad Politecnica de Valencia
Tampone G., 1999, Tradition and Innovation in the Timber Structures. Study and Conservation, ICOMOS Gen. Ass., Mexico City
Tampone G., 1999, Catalogo della Esposizione di plastici di strutture di legno antiche, Boll. Ing. n. 12