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Comprehensive, professional refurbishment saves Hotel Lonca from demolition
This project is an example of what KÖSTER stands for: Extending the life cycle of buildings. In this case, hundreds of tons of concrete and other materials were saved, as well as energy, time and money. The decision to renovate the existing building instead of demolishing and building a new one meant that the CO2 footprint was reduced enormously. Hotel Lonca is located in the small medieval town of Škofja Loka in the Slovenian Alps. It was opened in 1971 and operated until 2005. After decades of vacancy, however, it had become so run-down that the owner considered demolishing it.
Pictures: Inventory of the building fabric in its condition before the start of the renovation
Task
Our partner in Slovenia, Uroš Malovrh, gave the owner the idea of transforming the building into a modern hotel through extensive renovation and refurbishment. In 2019, Uroš began analyzing and documenting the condition of the building and developed a concept for the renovation using numerous KÖSTER products. This approach made it possible to determine that, in addition to waterproofing the building, numerous other problems had to be solved, e.g. the issue of "condensation" or moisture regulation in the basement to prevent mold growth. In line with the motto "Where water is the problem, we have a solution", the aim for experts like Uroš Malovrh is to protect a property in the long term and thus preserve valuable building structure.
The challenge
It was a very difficult and complex task, as the structure had been badly damaged over the years of vacancy and there was water everywhere in the building. Renovation work then began in 2022, during which Uroš, as an expert in structural waterproofing and renovation, was on site almost every day to answer questions from the owners, planners and contractors, as new challenges that could not have been foreseen at the outset constantly arose as the work progressed.
Solution
Uroš offered several technical solutions and ensured proper supervision of the correct and professional installation of the KÖSTER products. All related work was carried out by companies that had previously completed all the necessary training.
The areas of application for KÖSTER products included interior and exterior basement waterproofing, pressure injections for dry and damp cracks, joint waterproofing for mineral and metal substrates, waterproofing cable and pipe penetrations, roof waterproofing and the renovation of mold-infested rooms. More than 25 different KÖSTER products were used here from the basement to the roof.
In detail:
First of all, the concrete structure, which had been damaged by weathering over the years, had to be repaired and protected for the future. After uncovering the reinforcing steel, it was immediately apparent that additional action was required here, as the concrete and steel were already heavily corroded.
Image: Corroded reinforcement in the ceiling construction
This work step was carried out with the corrosion protection system for reinforcing steel, consisting of KÖSTER Z1/Z2. KÖSTER Repair Mortar R4, which is characterized by its high chemical and mechanical resistance, was used for the statically relevant concrete replacement in accordance with EN 1504-3. Depending on the degree of corrosion, the reinforcement was replaced and the concrete reinforced.
Pictures: ready for the first restoration steps with KÖSTER Z1/Z2 and KÖSTER Repair Mortar R4
The crack filling of the concrete construction could be carried out with KÖSTER Micro Grout 1C, as it is even suitable for crack widths of up to 0.2 mm due to its fine grain composition.
Water-bearing cracks were injected in two stages with KÖSTER 2 IN 1, which could be drained in the first stage by reacting with the water present in the crack and foaming. The crack was finally sealed by repeated injection with the same material.
Image: Set packers ready for injection
Image: Crack injected with KÖSTER 2 IN 1 on the ceiling in the basement
Before the large-scale exterior and interior waterproofing work could begin, the pipe penetrations had to be professionally waterproofed. Our KÖSTER KB-Flex 200 sealing compound was used here, which is suitable for water pressures of up to 0.75 bar, as well as KÖSTER KB-Fix 5 for the flush finish to hold the pipes in their final position and for a suitable substrate for the subsequent mineral waterproofing system.
Depending on the type of joint and its size, different systems were used for joint waterproofing: KÖSTER FS Joint Sealant based on polysulphide and for wider joints our KÖSTER Joint Tape 20.
Then it was time for the interior waterproofing (negative side waterproofing) in the basement area, as this was unavoidable: in some places, running water was coming out of the walls, so that this task could only be solved with the KÖSTER basement waterproofing method. This means that negative-side waterproofing can be carried out quickly and cost-effectively, even when water is constantly ingressing.
KÖSTER Polysil TG 500 was applied from the inside as a primer on all other wall surfaces in contact with the ground and then the KÖSTER NB 1 Grey waterproofing slurry was applied. The fillets and voids were created or filled in advance with KÖSTER WP Mortar.
Picture: Water ingress in the cellar
In order to make the rooms in the basement fully usable, a mold remediation system with KÖSTER Hydrosilicate Boards was the right solution. Advantages: In a purely physical way, this system removes the basis for mold growth. The KÖSTER Hydrosilicate Board has a moisture-regulating effect, reduces condensation due to its heat-insulating effect, and creates a pleasant room climate. The high alkalinity and the constantly dry surface prevent the formation of new mold.
Picture: Ceiling view of the bonded KÖSTER Hydrosilicate Boards
Picture: Hydrosilicate Boards filled with KÖSTER Hydrosilicate Adhesive SK
Picture: Completed ceiling made with KÖSTER Hydrosilicate Boards
There were also plenty of challenges on the outside, e.g. repairs had to be made to the existing but only partially functional bitumen waterproofing. This was particularly the case with details and connections. KÖSTER KBE Liquid Film was used here.
A crack-bridging waterproofing made of KÖSTER NB 4000 was used for the parapet consisting of concrete blocks in the area of the roof terrace. The additional addition of KÖSTER NB 4000 Spray Additive extended the working time of the mixed material, which simplified the application.
As asphalt was to be laid in front of the hotel entrance and chloride contamination from de-icing salts was to be expected during future use, the underlying concrete structure first had to be protected from this attack. KÖSTER CT 225 Bridge Deck Coating took on this task. Prior to further waterproofing measures and asphalting, KÖSTER Bitumen Primer was used as an adhesion promoter on the KÖSTER CT 225 Bridge Deck Coating.
Entrance area of the hotel – before
Entrance area of the hotel – after
To ensure that the hotel blends perfectly into the landscape, a mixture of an exposed roof and a green roof was considered in the planning from the outset, which was ultimately made possible with our root-resistant KÖSTER TPO 1.8 roof waterproofing membrane as the basis for the subsequent greening.
Pictures: finished KÖSTER TPO 1.8 waterproofing membrane ready for subsequent greening
This is because, having passed the FLL test, the resistance to root penetration is proven and leaves the design scope open without restrictions.
A particular challenge was to connect the TPO roof waterproofing membrane to different substrates in a backflow-proof manner, which is not possible with the conventional approach. Here, KÖSTER MS-Flexfolie with KÖSTER Superfleece was used as an insert. KÖSTER PU-Flex 25 was used for waterproofing the wall connection profiles.
Pictures: Completed roof with strips of greenery on KÖSTER TPO 1.8 after two years of use
Certain roof areas were equipped with steel structures that could basically be reused, but had to be protected against corrosion. After careful cleaning as substrate preparation, KÖSTER Corrosion Protection was used with subsequent surface coating consisting of KÖSTER CT 228 Flex.
For the interior design, the owners opted for elements of wood, glass, and steel, which creates a very cozy and warm atmosphere in the rooms. The professional approach of everyone involved in the process has led to a successful restoration of the building.
Pictures: Impressions of the interior design of the hotel
The Hotel Lonca in Škofja Loka is another example of the professional competence of the KÖSTER partners and the KÖSTER product systems.
Products used:
KÖSTER 2 IN 1
KÖSTER Bitumen Primer
KÖSTER Low Fire Load Vapor Barrier
KÖSTER CT 225 Bridge Resin
KÖSTER CT 228 Flex
KÖSTER Roof Drain without Leaf Catcher NW 100 light gray
KÖSTER Roof Vent with cap NW 75
KÖSTER FS Primer 2K
KÖSTER Joint Tape 20
KÖSTER Joint Filler FS-H black
KÖSTER Resin Mixer 100 mm
KÖSTER Hydrosilicate Adhesive SK
KÖSTER Hydrosilicate Board
KÖSTER Injection Adhesive 1C
KÖSTER KB-Fix 5
KÖSTER KB-Flex 200
KÖSTER KB-Pox Adhesive
KÖSTER KBE Liquid Foil
KÖSTER Basement Sealing Method
Galvanized leaf trap screen NW 100
KÖSTER MS-Flex Foil
KÖSTER NB 1 gray
KÖSTER NB 4000
KÖSTER NB 4000 Spray Additive
KÖSTER Polysil TG 500
KÖSTER PU Primer 120
KÖSTER PU-Flex 25
KÖSTER PUR Cleaner
Quartz sand 0.20 - 0.80 mm
Quartz sand 0.35 - 1.50 mm
KÖSTER Trowel for slurries
KÖSTER Repair Mortar R4
KÖSTER Restoration Paint white
KÖSTER SB Adhesive Emulsion
KÖSTER Barrier Mortar WU
KÖSTER Superfleece
KÖSTER Superpacker 10 mm x 115 mm with conical head nipple
KÖSTER TPO 1.8
KÖSTER TPO 2.0 U
KÖSTER TPO Cleaner
KÖSTER TPO Primer for MS-Flex foil
KÖSTER TPO Pro 1.8
KÖSTER Composite Sheet
KÖSTER VGM swellable
KÖSTER Waterspout DN 100
KÖSTER Rust Protection Z 1
KÖSTER Rust Protection Z 2
Executing company
- Konstruktplan, Jernej Bohinc s.p. - Installation of KÖSTER TPO roofing membranes
- Hidrosanir d.o.o. - injection works
- GRADE ECO d.o.o. - waterproofing under asphalt at the pedestrian path
