From Realtà Mapei International n° 90 - 4/13/2022

Giorgio Gaber Theatre

Grand reopening 22 years after its closure. Mapei’s contribution to the restoration works in the interiors and exteriors
Location icon Milan
Inaugurated in 1796 and originally named Teatro Della Cannobiana, the building hosting this theatre was designed by Giuseppe Piermarini in 1776. The original structure (with four rows of boxes, a gallery and two upper circles) was later modified following restoration work in 1893 and 1932, and especially after the fire that partially destroyed the theatre in 1938. When it was rebuilt by the architects Cassi and Ramelli following the fire, the boxes were eliminated. The theatre, which is now called the Teatro Lirico Giorgio Gaber, reopened its doors to the public last December after being closed for 22 years. Following the rebuilding work to bring the theatre back to its previous condition after the bombardments in 1943, apart from the second overhanging central gallery, the current theatre is much the same as it was back in 1940.
 

Renovation of the interior and exterior

The conservative restoration project, funded entirely by Milan City Council, included renovation work on both the interior and exterior of the structure. Inside the building, theatregoers can now find new gilding on the large, shell-shaped vaulted ceilings and other decorative features, herring-bone oak parquet flooring in the stalls, and red, black and white marble in the foyer. The walls are covered with pink granite and marmorino plaster while the ceilings are adorned with decorative features in gypsum which were recently restored.
Outside the theatre, works included restoring and reintegrating the render in the same colour as the original. This included the application of both mineral-based coatings on the neoclassic façade in front of Via Larga and coloured paste plasters on the remaining prospects. Restoration also involved a thorough cleaning and the water repellent treatment of the parts in pink granite and ornamental stone. The conservative restoration works also included the large porch, the fly tower and the dressing rooms/service unit and rehearsals rooms.
The biggest chunk of work, however, is hidden from view from visitors and included structural strengthening work on several sections of the building, the removal of asbestos, anti-seismic upgrading of the structure and an upgrade of the services equipment and acoustics.

Working together with the local Heritage Authority, designers and contractors

As Technical Sponsor from the start of the project in 2016, Mapei participated in the conservative restoration work and in the upgrading of the structure by supplying products and providing on-site support. The solutions supplied for the project were defined after carrying out in-depth chemical and physical analyses, testing and sampling procedures approved by Milan City Council and the designers. The analyses were all carried out in the Mapei Research and Development laboratories and accurately pinpointed the root cause of the problems that caused deterioration phenomena, the composition of the mortars and finishes originally used, or different restoration works carried out previously that had overlapped one another. In the case of the conch vaulted ceiling, for example, the analysis carried out proved to be indispensable in showing the Works Director that, underneath a good five layers of white paint, there was a finish similar to gold leaf. This meant that the original décor could be conserved and today may be viewed in its entirety. Testing and sampling were carried out on each and every system and technology employed to verify what had been proposed and to receive the approval of the Works Director from Milan City Council and all the designers involved. 
Numerous Mapei products and systems were used in the various stages of the work, such as :
  • CONSOLIDANTE ETS WR was used to consolidate the surface of weak, crumbling substrates, the ideal product for the conservative restoration and consolidation of porous stone, brick, terracotta and renders. Beside consolidating substrates, it also has high water repellent properties, which make it ideal on surfaces that might come in contact with rainwater. PRIMER 3296 was also used on most masonry substrates before applying renders and skim coats. This is an acrylic polymer-based water dispersion primer, with high penetration characteristics, even on surfaces with low porosity.
  • SILANCOLOR CLEANER PLUS mould- and algae resistant solution was used to provide a hygienising treatment for the damaged render on the brick, stone and tuff masonry.
  • To strengthen the extrados of the floor slabs with steel joists, the connection of the joists to the walls was improved by anchoring the ends in the walls around the floors with MAPEFIX VE SF and applying a coat of EPORIP resin and PRIMER 3296 along each steel joist.
  • An FRP strengthening system was proposed to strengthen the reinforced concrete beams. After protecting the reinforcing rods with MAPEFER 1K and integrating their surface with PLANITOP SMOOTH & REPAIR R, the concrete beams were strengthened by applying a coat of MAPEWRAP PRIMER 1 on the surface of the intrados of the beams followed by a layer of MAPEWRAP 11. The next step was to apply CARBOPLATE plates on the intrados of the beams. To increase the shear strength of the beams, and at the same time minimise the potential “debonding” effect in the longitudinal carbon-fibre strengthening, MAPEWRAP C UNI-AX unidirectional, high-strength carbon fibre fabric was applied around the supports.
  • The extrados of the masonry vaulted ceilings was strengthened by applying MAPE-ANTIQUE STRUTTURALE NHL natural hydraulic lime- and Eco-Pozzolan-based mortar, which is physically and mechanically compatible with the substrates, and MAPEGRID G 220 glass fibre mesh along the extrados of the areas to be strengthened.
  • Restoration of damaged and deteriorated render was carried out by firstly applying MAPEWALL INTONACO BASE natural hydraulic lime-based base render. Then, after skimming the surfaces with PLANITOP 510 fine-graded, lime-cement based skimming compound, the surfaces were painted with SILEXCOLOR BASE COAT and SILEXCOLOR PAINT in the colour shade chosen by the Works Direction.
  • Restoration of damaged and deteriorated render was carried out by applying MAPE-ANTIQUE INTONACO NHL cement-free, natural hydraulic lime-based breathable base render. MAPE-ANTIQUE FC CIVILE salt-resistant, fine-grained lime and Eco-Pozzolan based transpirant skimming mortar was then used to skim the surface, followed by SILEXCOLOR BASE COAT and SILEXCOLOR PAINT to paint the surfaces in the colour shade chosen by the Works Direction.
  • The concrete was repaired using various products: MAPEGROUT 430 thixotropic mortar; MAPEGROUT HI-FLOW mortar and MAPEGROUT T40 thixotropic mortar, all mixed with MAPECURE SRA.
  • The joints in the new marble floors in the corridors and foyer were grouted with ULTRACOLOR PLUS grout chosen in different shades in order to match the colour of the existing joints.
  • The integration and restoration of the finishes on the steps of the staircases was carried out by applying ULTRATOP LOFT SYSTEM: firstly, the substrate was mechanically prepared, with the consequent removal of the dust, and primed with PRIMER SN, which was fully blinded, while still fresh, with QUARTZ 0.5 quartz sand. After the hardening of the primer and the elimination of the excess quartz, ULTRATOP LOFT W, one-component, fine-textured cementitious paste, was applied with a flat metal trowel, to create (up to 2 mm thick) decorative floor and wall coatings with a trowelled or mottled finish. After its hardening, the surface was sanded and dust was removed before applying PRIMER LT, one-component, acrylic adhesion promoter, diluted with water at a ratio of 1:1 by weight. After the complete hardening of PRIMER LT, the second coat of ULTRATOP LOFT W was applied with a flat metal trowel. The surfaces were then sanded and vacuumed before applying ULTRATOP BASE COAT, one-component acrylic formulation in water dispersion. The final finish was created by applying a coat of transparent MAPEFLOOR FINISH 58 W, two-component, aliphatic, matt polyurethane finish in water dispersion with a mohair type roller.
  • The external render was restored by applying MAPE-ANTIQUE STRUTTURALE NHL natural hydraulic lime-based mortar with high ductility and MAPEGRID G 220 glass fibre structural mesh around the extrados of the span of the vault requiring strengthening. The render was then finished off by applying two coats of MAPE-ANTIQUE FC GROSSO cement-free, large-grained, lime-based skimming mortar, followed by a coat of SILEXCOLOR BASE COAT and then two applications of SILEXCOLOR TONACHINO textured silicate coating paste with high breathability, for internal and external surfaces, in the same colour as the original.
  • Conservative restoration of the neoclassic façade in Via Larga was carried out by removing the deteriorated render, reintegrating it with MAPE-ANTIQUE          INTONACO NHL, applying a coat of SILEXCOLOR BASE COAT to even out the substrate and then applying SILEXCOLOR PAINT silicate-based paint in the same colour as the original.
  • Conservative restoration of the finishes in the main vault and in the foyer by applying MALECH base coat and COLORITE PERFORMANCE protective acrylic paint, with high resistance to UV rays, in the same colour as the original finishes.
  • The conservative restoration of the finishes on the walls in the corridors, in the stair wells and the auditorium with a "plaster-effect" finish included the removal of the plastic coating, the application of PRIMER 3296 to even out the absorption of the substrate, PLANITOP 560 lime-cement mortar to smooth over the surfaces, SILEXCOLOR PRIMER to even out the substrate, and SILEXCOLOR MARMORINO silicate-based plaster in the same colour as the original.

Project data sheet

Yard historical theatre
Location Milan, Italy
Subcategory THEATRE
Built in 1776
Opened in 1796
Application supplying technical support on site and products for structural strengthening, restoring and rebuilding renders, restoring existing coatings and applying new coatings
assistenza tecnica continua in cantiere, il ripristino e il risanamento degli intonaci, gli interventi di impermeabilizzazione e di posa di rivestimenti, il restauro delle finiture esistenti e la stesura di nuove finiture.
Start and finish date 2015/2021
Application Type Concrete restoration systems, Facade interventions, Masonry restoration
Client Milan City Council, Councilor for Public Works and House – Technical Area for Culture
Contractor company Impresa Garibaldi - Fragasso
Specialists involved Executive design and works direction: Pasquale Francesco Mariani Orlandi, Milan City Council Superintendency of Archeology, Fine Arts and Environment: Antonella Ranaldi, Paolo Savio
Credits Gianni Dal Magro
Project Manager Massimiliano Papetti, Milan City Council
MAPEI Coordination Davide Bandera, Alberto Arosio, Mapei SpA (Italy)
Other Francesco Maggiore, Fondazione Dioguardi

Products mentioned in the article

CARBOPLATE SYSTEM
CARBOPLATE SYSTEM
Structural strengthening system consisting of pultruded plates In high-strength carbon fibre and epoxy resins to bond the Plates (frp)…
COLORITE PERFORMANCE
COLORITE PERFORMANCE
Protective acrylic paint with high resistance to UV rays for internal and external use, available in a wide range of colours. TECHNICAL…
CONSOLIDANTE ETS WR
CONSOLIDANTE ETS WR
Water-repellent, tetraethyl orthosilicate-based consolidator in solvent for the conservative renovation and consolidation of porous stone,…
EPORIP
EPORIP
Two component solvent-free epoxy adhesive for construction joints and for monolithic sealing of cracks in screeds. TECHNICAL DATA:…
MALECH
MALECH
Water-based acrylic undercoat and bonding promoter with a smooth finish. TECHNICAL DATA: Consistency: fluid liquid. Colour: transparent.…
MAPE-ANTIQUE FC CIVILE
MAPE-ANTIQUE FC CIVILE
Salt-resistant, fine-grained lime and ECO-POZZOLAN cement-free, breathable skimming mortar for a natural finish on render. TECHNICAL DATA:…
MAPE-ANTIQUE FC GROSSO
MAPE-ANTIQUE FC GROSSO
Salt-resistant, large-grained lime and ECO-POZZOLAN cement-free, breathable skimming mortar for a rough finish on render. TECHNICAL DATA:…
MAPE-ANTIQUE INTONACO NHL
MAPE-ANTIQUE INTONACO NHL
Breathable base render made from natural hydraulic lime and ECO-POZZOLAN, cement-free, for application on existing masonry work, including…
MAPE-ANTIQUE STRUTTURALE NHL
MAPE-ANTIQUE STRUTTURALE NHL
High-performance mortar for breathable render and masonry work, based on natural hydraulic lime and Eco-Pozzolan, particularly suitable…
MAPECURE SRA
MAPECURE SRA
Curing admixture for cementitious mortar and concrete to reduce hydraulic shrinkage and the formation of micro-cracks. TECHNICAL DATA:…
MAPEFER 1K
MAPEFER 1K
One-component, anti-corrosion cementitious mortar for steel reinforcement rods. TECHNICAL DATA: Maximum dimension of aggregate: 0.5 mm.…
MAPEFIX VE SF
MAPEFIX VE SF
Styrene-free, hybrid vinyl resin-based chemical anchor for structural loads. Certified for threaded bar, construction bars and C1 seismic…
MAPEFLOOR FINISH 58 W
MAPEFLOOR FINISH 58 W
Two-component, aliphatic, transparent or coloured, matt polyurethane finish in water dispersion. TECHNICAL DATA: Mixing ratio: comp. A:…
MAPEGRID G 220
MAPEGRID G 220
Alkali-resistant, pre-primed glass fibre mesh for structural “reinforced” strengthening of stone, brick and tuff and mixed masonry…
MAPEGROUT 430
MAPEGROUT 430
Fine-grained, fibre-reinforced, normal-setting thixotropic mortar for repairing concrete. TECHNICAL DATA: Maximum dimension of aggregate: 1…
MAPEGROUT HI-FLOW
MAPEGROUT HI-FLOW
Fibre-reinforced, controlled-shrinkage mortar for repairing concrete. TECHNICAL DATA: Maximum dimension of aggregate: 2.5 mm. Mixing ratio:…
MAPEGROUT T40
MAPEGROUT T40
Medium-strength (40 MPa), compensated-shrinkage fibre-reinforced thixotropic mortar for repairing concrete. TECHNICAL DATA: Maximum…
MAPEWALL INTONACO BASE
MAPEWALL INTONACO BASE
Breathable natural hydraulic lime-based base render for external and internal use; to be applied by trowel or with a rendering machine.…
MAPEWRAP 11
MAPEWRAP 11
Two-component, normal-setting, thixotropic epoxy grout for evening out concrete surfaces and for structural bonding. TECHNICAL DATA: Mixing…
MAPEWRAP C UNI-AX SYSTEM
MAPEWRAP C UNI-AX SYSTEM
Structural strengthening system consisting of high-strength high-modulus unidirectional carbon fibre fabric and epoxy resins to impregnate…
MAPEWRAP PRIMER 1
MAPEWRAP PRIMER 1
Two-component epoxy primer specifically formulated for the MAPEWRAP system. TECHNICAL DATA: Mixing ratio: comp. A : comp. B = 3 : 1.…
PLANITOP 510
PLANITOP 510
Lime-cement skimming mortar with a fine-textured, natural finish for render. TECHNICAL DATA: Maximum size of aggregate: 0.4 mm. Mixing…
PLANITOP 560
PLANITOP 560
Lime-cement skimming mortar with an ultra-fine-textured finish for render. TECHNICAL DATA: Maximum dimension of aggregate: < 0.1 mm. Mixing…
PLANITOP HPC FLOOR
PLANITOP HPC FLOOR
Fibre-reinforced, shrinkage-compensated, high-strength, high-ductility, highly-fluid cementitious mortar.
PLANITOP SMOOTH & REPAIR R4
PLANITOP SMOOTH & REPAIR R4
Structural R4-class, rapid-setting, shrinkagecompensated, thixotropic, fibre-reinforced, cementitious mortar, applied in a single layer…
PRIMER 3296
PRIMER 3296
Acrylic primer in water dispersion with high penetration, consolidating and anti-dust properties for screeds. TECHNICAL DATA: Consistency:…
PRIMER LT
PRIMER LT
Acrylic adhesion promoter for ULTRATOP LOFT and cementitious skimming mortars. For internal use. TECHNICAL DATA: Consistency: fluid liquid.…
PRIMER SN
PRIMER SN
Two-component epoxy primer with fillers. May be coloured with MAPECOLOR PASTE. TECHNICAL DATA: Mixing ratio: component A : component B = 80…
QUARZO 0,25 - 0,5 - 0,9 - 1,2 - 1,9
QUARZO 0,25 - 0,5 - 0,9 - 1,2 - 1,9
Washed kiln-dried quartz sand for use with epoxy and polyurethane resin
SILANCOLOR CLEANER PLUS
SILANCOLOR CLEANER PLUS
High penetration and mould-and algae resistant hygienising treatment. TECHNICAL DATA: Consistency: fluid liquid. Colour: transparent.…
SILEXCOLOR BASE COAT
SILEXCOLOR BASE COAT
Transpirant, coloured silicate undercoat with a smooth finish and good filling properties for internal and external surfaces, according to…
SILEXCOLOR MARMORINO
SILEXCOLOR MARMORINO
Highly-decorative, fine-grained, silicate mineral coating product in paste form with high chemical resistance for internal and external…
SILEXCOLOR PAINT
SILEXCOLOR PAINT
Highly-transpirant silicate paint with a high chemical bond for internal and external surfaces, according to DIN 18363 Standards. TECHNICAL…
SILEXCOLOR PRIMER
SILEXCOLOR PRIMER
Highly breathable silicate primer compliant with DIN 18363 standards. TECHNICAL DATA: Consistency: fluid liquid. Colour: transparent.…
ULTRACOLOR PLUS
ULTRACOLOR PLUS
High-performance, antiefflorescence, quick-setting and drying polymer-modified mortar free from Portland cement with water-repellent…
ULTRATOP BASE COAT
ULTRATOP BASE COAT
One-component acrylic formulation in water dispersion used as a base coat before applying protective finishes on Ultratop, Ultratop Living…
ULTRATOP LOFT F
ULTRATOP LOFT F
One-component trowellable coarse-textured cementitious paste applied in layers up to 2 mm thick to create decorative floors with a…
ULTRATOP LOFT W
ULTRATOP LOFT W
One-component trowellable fine-textured cementitious paste applied in layers up to 2 mm thick to create decorative floors with a trowelled…
Realtà Mapei Tags: #renovation #architecture

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