Venice is built on unstable ground. Facades are distorted, floors uneven  and cracks are numerous.

Precise surveying and monitoring enables the origins of this  deformations to be understood and indicates if facades where already built tilted inwards to avoid a more dangerous tilting outwards. Iron ties, original or added, hold floors and walls together.

Much of the deformation took place during construction (brick and stone courses are uneven at lower levels and become more and more horizontal at each successive floor: evidence that the foundations were settling during construction. The later addition of  floors or new constructions  nearby  could cause significant additional settlements.

 

The deformations of several decimetres that we measured in our surveys  took centuries or very traumatic events to develop and are usually  not a cause for alarm (the much-debated sinking of Venice is another topic: subsidence in the highly industrialized post-war period was mostly due to the extraction of cheap ground water for industrial use and the  phenomenon seems to have arrested since restrictive laws were introduced).

If the foundations do not show any more differential settlement, localized actions, like tying tilted walls to the floors  and roof etc. will often be sufficient to improve  resistance to earthquakes (the most devastating one for Venice being recorded at the beginning  of the 16^th Century).

Things become more alarming if new cracks appear or old ones start to reopen.

A very efficient way of measuring ongoing deformations is periodic high precision levelling (1/100 of a mm). Tilting and cracks can also be monitored, but in most cases they show the consequences of horizontal settlements of the foundations.

 

Why do some foundations still settle in Venice?  Equilibrium in the unstable ground is very delicate: although the wooden piles and planks used by builders until the 19^th century to consolidate the ground under load-bearing walls are mostly found in a good state of conservation, they  rarely  reach the deeper and more resistant layers as do modern foundations (on concrete pillars, for example).  Foundations along canal-sides are constantly being eroded  by the activity of  the tides and the waves generated by motorboats.  The construction of septic tanks (the only way waste water is treated in Venice and mandatory for the frequent transformation of housing into hotels and restaurants) close to foundations or the carelessly executed consolidation of waterfronts are other causes.

The latter was the cause of the settlements  and consequent crack formation in  the following constructions we happened to monitor:

 

Venetian residential constructions are particularly well suited to have a long life (and are therefore very “sustainable”), not only  because they were built with skill and good materials but also because they have very flexible layouts: to avoid load concentration on the unstable ground (see SINKING HOUSES), only a strict minimum of walls were built to carry floors supported by very narrow wooden beams with spans of between 5 and 8m . Partition walls were made of wood covered with plaster. These light partitions can easily be moved. Often, only the long sides of the central hall have load-bearing walls, while the short sides consist of huge windows.

Small houses often repeated the pattern used in patrician palaces from the 16^th to the 18^thcentury, where the central hall served to  accommodate several hundred guests. During less prosperous periods, these large rooms were often divided into smaller ones, especially during the 19^th century, when Venice became home for a crowded, but mostly poor population.

The following two projects show how generous this layout is, and how easily a new (or old) spatial distribution can be created or recreated.

 

Borgoloco (public courtyard) Pompeo Molmenti is flanked by a row of  nearly identical small buildings, built after 1500 and reusing older walls.  They have been through several transformations (in the 18^th century two were joined by opening doors in the party wall and modifying the staircases). In the 19^th century both constructions were separated again (simply by bricking up the doors, leaving the marble jambs in place) and in 1930 wooden partition walls were erected to transform the central hall into a landing for the stairs, a kitchen, the entrance and a relatively small living-room.

 

The narrow kitchen and the large, unlit entrance hall are unsuitable for the use of the present owners. Since it is easy to remove the 1930s partition walls, the magnificent, 4 m-wide and 11m-long central hall will be restored and the kitchen moved to another place. The stairway has to be modified to make each apartment independent (the main hall gave common access to all the other rooms, including the flight leading to the upper floor). The solution proposed for the stairs is current in Venice, where condominium ownership dates back to the Middle Ages  and most buildings were divided through inheritance arrangements several times over the centuries.

 

Again the second floor of this construction has undergone several transformations to accommodate numerous families for almost 6 centuries. Added in the mid-15^th century (some previous roof beams are still incorporated into the masonry) and covered with a ceiling able to carry at least 1 other storey, its layout is typical of late “Gothic” palaces: an L-shaped main hall (grey) with rooms on each side of the longer part of the L.

At the end of the 18^thcentury a third storey was added above the main façade and the Gothic window that illuminated the L-shaped hall of the second floor was replaced by a “modern” but smaller, arched window. Probably it was intended that the interior of this floor would be transformed too,  but the Napoleonic wars must have stopped construction.

In 1804, after the overthrow of the Venetian Republic, a certain Comarolo, who had rented  the building from the Giustinian family, bought it and used old letters and other papers from his father to fill the cracks in the beams of the ceiling of the hall before repainting them grey.

 

The discovery of these documents enabled a reconstruction of the floor’s history, showing  that in the early 19^th century  the hall was still L-shaped and only in the mid-19^th century, after new owners bought the construction, were ceilings lowered and partition walls erected to create two drawing rooms along the main façade and a long, badly illuminated  corridor in what was formerly the longer part of the L.

 

Traces on the floor, partially demolished and reconstructed plaster ceilings and bricked-up windows show that the position of these partition walls changed considerably with each generation of new owners.

The aim of the present restoration was to reopen the L-shaped main hall together with  the bricked-up windows to allow light once again to enter the 25 m-deep living area.

 

 

The kitchen dating from the 1950s, situated in the rear of the apartment, was kept as a laundry-room and  a new kitchen was created in place of a former bathroom: a former bedroom thus became a dining room with access to the spacious 80m² terrace.

 

 

How were medieval constructions “finished”? Palazzo Donà della Madoneta was last restored in the 1940s, when a 19^th century plaster with fake marble decoration was removed from the façade on the Grand Canal to show the “original” brick curtain wall dating back to the construction of the building sometime after 1290.  The mortar joints show very carefully made incisions and one might think that this was the finish that medieval builders wanted to be seen.

When the plaster applied in the 1960s to the remaining facades was carefully removed, interesting stratifications appeared (see READING A FAÇADE) and a microscopic fragment of thin red-painted plaster gave a hint about possible decoration that had been lost over time.

 

 

Inside, stratigraphic analysis  revealed mostly 19th/early 20^thcentury decorations, as in the main staircase (former courtyard) rebuilt in this period, where coloured patterns imitating medieval wall paintings emerged (at a first glance they were taken for “original”, but further investigations showed that they were applied on industrial bricks). Since the survey revealed that the “piano nobile”, the main hall facing the Grand Canal, was formerly reached through a monumental door at the top of what must have been an outside staircase mentioned in an archive document from 1425 and that the modern finishing layer probably concealed precious information about the medieval palace, the plaster was removed.

 

Once the plaster was removed, the monumental door, in line with the only pilaster of the loggia (which is otherwise made of reused, antique columns in marble from Marmara) revealed a gratifying surprise: the stone lintel is surmounted by a an arch made of carefully polished bricks with millimetric joints and a geometrical decoration carved into the bricks.

 

But there is even more: the bricks of the arch are covered with tiny fragments of red painted plaster the same as those already observed on the outer facades but with larger areas perfectly preserved: fake bricks painted with great care on perfectly worked and jointed bricks.

We know these decorations  were frequent  in the  15^th and early 16^th century and they are beautifully depicted on paintings of that period (see for example Carpaccio’s cycle of the Miracle of the Holy Cross, now at the Accademia Gallery)  and there are fragments conserved on several façades and inside churches. A brilliant architect reused them in 1905 for his own house, the casa Torres on Rio del Gaffaro, and specialized literature calls it regalzier.

Further investigations might tell if the regalzier of Palazzo della Madoneta was added one or even two centuries after its construction or if this apparently strange taste for painting bricks on bricks persisted in Venice over several centuries.

 

Historic buildings get transformed with every generation. It is challenging to attempt a mental reconstruction of the form buildings assumed at a precise moment in time or to understand the aesthetic intentions, the constructional constraints  or social needs of a historical period (and therefore to position ourselves). Historians ideally try to overlay written or iconographic evidence with archaeological inquiries. Unfortunately, in most cases, only one of these approaches is possible and the interpretation is therefore partial.

Palazzo Donà della Madoneta passed by inheritance through many owners between1425 and the end of the Venetian Republic in 1797. From 1290, the date of the earliest archival document describing a construction in this position on Grand Canal, until 1797, it had never been divided and no  legal controversies  about its ownership are recorded in the State Archive (special thanks to Jan-Christoph Röessler who did the research).  Though few written documents have emerged and only a few sketches, paintings and historic photographs have been found, we can rely on numerous direct observations that emerged during renovation work in order to understand certain aspects of its history.

The now removed plaster on the façade at right angles to the Grand Canal, originally painted orange and dating from 1960, concealed a considerable quantity of information.

 

 

What seemed to be a later addition turned out to be a construction already mentioned in 1425 and owned by the Emo family when they bought the entire block (see B and C, figure above): the part closer to the Grand Canal (B) was built with bricks similar to those used for the structure facing the Grand Canal (A) and might even be older;  the rear part (C) was an addition built with reused bricks of different formats. Both have undergone substantial transformation, as shown by closer analysis of the windows and their surrounding walls. During the 16^th century 4 arched windows with Renaissance mouldings were inserted into the older part (B)and in the 18^th century both parts (B and C) were joined with the addition of 7 arched windows and a cantilevered fireplace. On this occasion, older windows in the rear part (C) were bricked up or covered by the chimney and the Renaissance mouldings (in B) were cut away so that all the windows in B and C matched stylistically.

Unsurprisingly only one of the 28 present windows is still in its “original” place (on the top right in C, see  figure above). All the other windows have been bricked up, added or even transformed as seen above. The part facing the Grand Canal (A) retained its stylistically different windows. Here, the only other window contemporary with its surrounding wall was bricked up in the 19^th century (the top left window, see  figure above, with an architrave actually dating from the XV century) and the two chimneys, one of them still visible in a 19^th century photograph,  were probably removed as late as the 20^thcentury (when central heating was introduced).

The more information you collect from reading  a façade (see READING A FAÇADE ), the more difficult it is to make a choice when decisions about its renovation have to be taken. We know very little about the coating of the oldest parts (see IMITATING BRICKS ON BRICKS) and surviving fragments of later coatings can be misleading (thin layers of limewash, for example, extensively applied on the medieval brick curtain wall of the side façade were also present on the chimneys bricked up in the late 19^th or even 20^th century and were therefore already the result of a “restoration”).

 

The sand and lime mortar present in fragments on the latest part added (see  C, figure above) was applied prior to the opening of the 18^th century arched windows, while small fragments of ground brick and lime mortar found under the coating dating from 1960 (only in B and C) indicated  a render (or a  preparation layer of a so-called “marmorino” – a widely used plaster made of lime and stone powder) that is consistent with the 18^th century transformation.

Rigid conservation practice calls for the preservation of all “historic” layers (so we should have kept the orange painted plaster from 1960) and restoration theory  requires that newly added elements should be recognizable as such (actually the orange plaster was very recognizable as being “modern”…). But fortunately things are more complex: issues about the compatibility of “modern” construction materials with “traditional” ones add technical arguments and the aim of leaving the “history” of the fabric visible adds abstract considerations. If strong evidence of missing parts exists, even reconstruction might be considered (to do justice to the artistic, i.e. aesthetic intentions of the builders). Unmistakably “modern” additions open a Pandora’s box of aesthetic judgments which are usually carefully avoided in conservation work for not being “objective”.  There is, in the end, no single standard approach as can be seen from the very different results obtained in recent decades in Venice and abroad.

The various restorations of the façade facing The Grand Canal carried out in the late 19^th and 20^thcentury  illustrate well how the criteria guiding the restorations have changed over time: A photograph taken before 1913  by Naya shows the façade as an example of “Byzantine-Lombard style” covered  with plaster decorated with geometrical decorations, marble imitations, and a fake ashlar facing.

 

Careful analysis during our restoration revealed that the “Byzantine” arches  (stone cladding) were added in the 19^thcentury  and that the marble cross above the loggia  was originally  embedded in  the side façade (the former Emo property, see * in B, figure above, Palazzo Donà dela Madonata, façade at right angles to the Grand Canal during renovation). The decoration of the 19^th century plaster underlined this  “stylistic” reconstruction: the upper part of the façade in “Byzantine-Lombard style” was decorated with medieval motifs, while the mezzanine-floor and the ground floor with its water gate, both modified in the 16^th century, was plastered with fake marble and fake ashlar facing, i. e. typical “Renaissance” decorations.

In the 1930s  this plaster, by then considered “fake”, was removed together with the 19^th century cast iron balcony and two windows on the top floor were transformed into balconies (the authorization was given on condition that the remaining windowsills were realigned into their medieval position). Exposed brick was aesthetically highly regarded and while the 1930s windows imitated pre-industrial, small-square patterns, only one decade later the windows between the columns of the main floor were  replaced by the present large, recessed  glass curtain,  transforming the formerly narrow balcony into a loggia.

The current renovation has changed the façade on the Grand Canal less dramatically: only an expert eye will notice that two bricked-up windows have been reopened (inserting  invisible stainless steel frames for static reasons) and the capitals and twin columns in red limestone from Verona, carefully cleaned and consolidated, reveal layers of red paint applied prior to the 19^th century (petrographic analysis done by Lorenzo Lazzarini from IUAV University).

Analysis of the façade at right angles to the Grand Canal (see READING A FAÇADE) motivated a different approach: the part built together with the façade on the Grand Canal was left uncoated in continuation with the façade on the Grand Canal, repointing being confined to the deteriorated areas. Indeed it proved possible to conserve large areas of the original joints between the bricks (these are recognizable by a thin incision) and the transformations described above are still “readable”. The downside is that the surface has to be protected by an invisible hydrorepellent coat that will need periodical renewal.

 

 

The remaining part of the façade, i.e.  the old Emo property and its addition, heavily transformed and  unified in the 18^th century with the introduction of similar windows and now lost plaster, was covered with a new lime plaster. The latter is compatible with the heterogeneous brick wall but refrains from imitating a “historic” rendering (it contains yellow and grey sand and fragments of red and white limestone from Verona). The now visible imprint of the cross removed in the 19^th century and a joint indicate the centre and the limit of the old Emo property prior to 1425.  At the special request of the Soprintendenza (Ministry for Cultural Heritage and Tourism) some fragments of the pre-18^th century plaster present on the most recently added part of the building were left visible rather than re-covered: an arguable  instruction since this plaster was contemporaneous with a completely different layout of the façade,  while the new plaster covers the extension of the 18^th century transformation and is not the “restoration” of this older fragment as it now appears.

 

In 1940 ca. the 19^th century staircase of palazzo Donà della Madoneta that occupied a former courtyard was partially demolished to serve only the second floor (piano nobile). To reach the third floor you had to cross the entire building to reach a service staircase at the back. This was possible since the second and third floor had been used as a single, vast apartment at least since 1913. The present owners wanted to be able to use each floor separately again and the elevator from 1965 had to be replaced with a new one, accessible to wheelchairs. Space to comply with the local construction code was extremely limited and only an accurate Total Station survey (closed traverse with an error margin of less than 1mm) made it possible to establish the available space exactly even before demolishing the floor slabs from the 1940s.

Execution also had to be within millimetric tolerance to allow the handrails of the staircase to run around the elevator tower. To permit precise construction and to distribute the load on the same walls as the previous staircase (to avoid differential settlement since Venetian foundations are unstable, see SINKING HOUSES) a complex metal construction was designed.

The elevator now continues up to the roof terrace and the new landings were conceived as bridges to allow natural light to illuminate the entire new staircase with the existing windows.

Good architecture works for centuries. This apartment was created in the second half of the 18^th century simply by adding a floor on top of the main façade of a 15^th century palace (see BRINGING LIGHT INTO AN OLD PALACE: Palazzo Soranzo)

The ceilings are relatively low  (2.4m) and the central drawing-room is smaller than the other rooms, especially considering the floor beneath.  The 18^th century builder did an unexpected but apt thing: he opened no fewer than three doors in the minute drawing-room creating a 15 m-long visual axis parallel to the façade.

 

Different floor patterns and delicate decoration in the central drawing-room expand the space even more. As a result  this relatively small apartment becomes very generous and the terrace at the side allows the entire apartment to be embraced in a single glance from outside, doubling the already rich spatiality.

Consequently, the restoration was limited to the addition of an open kitchen,  the refurbishment of the bathroom and the restoration of the stucco decorations and terrazzo floors.

The book “Un restauro per Venezia” , co-edited with John Millerchip, illustrates the restoration of a city-owned  townhouse in Venice designated for social housing. The project was promoted by The Venice in Peril Fund, the British committee for the safeguarding of Venice, under the umbrella of UNESCO. The actual restoration work was financed by the Italian Government  (Legge Speciale per la Salvaguardia di Venezia). The aim was to create a concrete example of how respectful  conservation  practice that takes care of the distinctive features of the historic fabric of Venice is possible and financially feasible for social housing.  The project is a successful example of collaboration between private funding, public authorities and the University. It was the first time the innovative removal of damaging salt present in the walls was applied on a large scale (see ELIMINATING SOLUBLE SALTS FROM BRICKWALLS).