Castle Chapel of St Martin, St Erhard and St Ursula, Cheb, Czech Republic

cheb hlavni foto

Address:
Chebský hrad, Dobrovského 2062/21, 350 02 Cheb
Description of work: 
Specialist surveys 
Restoration of the interior of the lower chapel (stone elements, ceiling,floors)
Restoration of stone elements in the upper chapel
Treatment of the exterior casing
Setting up a system of climate control in the chapel
Carpentry, metal and glazier work
Investor:
The Town of Cheb
Contractor: GEMA ART GROUP a.s.
Implementation:  08/2000 – 12/2003

 

 

 

  • History
  • Restoration work
  • More information

 The history of the location goes back to the 9th century, when the Cheb area was inhabited by Slavs. On the site of today's castle stood an Early Medieval Slavonic fortified settlement with an ossuary burial ground, uncovered during the archaeological research. Changes which took place during the 12th century were due to low local population numbers and the distance of the settlement from Prague, the seat of the ruling Slavonic Přemyslid dynasty, whose influence on the Cheb area gradually weakened. The area was eventually annexed by the North Mark of Bavaria and the original Slavonic settlement converted into a stone-built castle.
Extensive building alterations took place in 1179 during the rule of the Emperor Frederick Barbarossa, when the palatinate was built. It was dominated by a round Black Tower (Bergfried), the palatial style castle and the Chapel of St Martin, St Erhard and St Ursula. The two-storey chapel is the best preserved part of the palatinate. The first written mention of its existence comes from 1213, when the Emperor Frederick II issued there his Golden Bull, a document determining the relationship between the ruler and the church. The double level chapel was designed as two entirely separated premises, the lower part intended for local worshippers and the upper one for the Emperor's private services. Each part had a separate entrance and the two levels had only been interconnected during building alterations undertaken in the 19th century. The most interesting feature of the lower chapel is its cross-vaulting supported by four columns. In 1930 a Cubist sculpture "The Blessing Christ", work of the local artist Josef Mayerle, was installed in the lower chapel. The upper chapel has a richer ornamentation. The capitals of its columns are decorated with sculptural motifs depicting bearded male heads and angels, most likely references to the four evangelists and to sins such as greed, fornication and of bearing false witness. The triumphal arch is decorated with bas-reliefs of 12 male heads, probably portraying the apostles.
The next instance of building alterations occurred when the Cheb area again became part of the Czech Kingdom. In 1322, during the reign of the King John of Luxembourg, the palatinate was rebuilt as a Gothic stronghold.
During the 15th century a new level was added to the Romanesque palatial castle, and utility buildings (so-called Kuchellhouse) and two towers (The Mill Tower and the Rock Tower) were erected. Later on, between the years 1652 and 1673, the whole complex was remodelled into an extensive Baroque citadel with brick-built fortifications and casemates.
The buildings were allowed to deteriorate during the 18th and 19th century. The chapel, and its roof in particular, was seriously damaged during the violent storms of 1762. The repairs were not carried out until 1818. Towards the end of the 19th century the administration of the castle was taken over by the town of Cheb and had since then, until 2011, been managed by the town museum. As of 1st January 2012 the castle has been run by the Cheb Town Council.

A complete restoration survey took place between 2000 and 2003, with the participation of a number of experts from several specialist organizations. Based on the findings of the survey a detailed blueprint for the restoration work was drawn up. Some restoration was carried out on the exterior, but the bulk of the work was done in the interior of both the lower and the upper chapel. The task of devising and implementing measures to lower the damaging levels of dampness in the lower chapel constituted a challenging part of the GEMA ART GROUP a.s. staff's restoration remit.

Specialist surveys:
Due to the exceptional historic significance of the Romanesque chapel, experts from many fields took part in the extensive surveys. Archaeological research carried out in 1997 and 1998 by the Cheb museum under the leadership of Dr Petr Šebesta and subsequent archaeological research in the Chapel of St Martin undertaken in 2000 constituted a platform for the current investigations.
Extensive petrographic examinations of the building stone materials and the plasters, as well as evaluation of silicate analysis of the historic plastering, measuring of the salinity of the stone and microscopic examination of sample fragments of the original colour palette were all carried out. Thanks to expert evaluation, the composition of the old mortars was also established. All the gathered information enabled the restorers to select the most suitable materials, which would fulfil the exacting quality requirements of the renovations. Where some specific original building components were beyond repair, petrographic analysis helped to locate available current sources of materials most appropriate for the manufacture of copies.
In order to select the best method of stone conservation, the levels of salinity had to be established. Concentrations of three salts (sulphate, chloride and nitrate) were examined and their levels were found not to be dangerous, with the exception of those present in the floor flagstones.
Microscopic examination of the colour samples gave some idea of the original colour appearance of the chapel, which was dominated by red and yellow hues. The collated results of the examination formed the basis for a detailed restoration proposal.

Restoration of the masonry in the lower chapel:
Problems here were caused by the high levels of dampness in the chapel premises. The rising damp particularly affected the pointing, which was severely defective.
Based on the results of the plaster analysis, a series of mortar samples was created and their mechanical properties and ability to withstand climactic conditions were evaluated.
To start with, the unsuitable modern plasters, affected by the rising damp, had to be removed and the original plastering conserved and strengthened using expanded organosilicate consolidates. The coarse-grain old mortar was consolidated using a solution of colloid silicate acid, which has a high resistance to adverse climactic conditions. Severely damaged fragments of masonry were also injected with a mineral substance containing a lime bonding agent. The stability of infilled cracks was secured using injections of a special formula with hydraulic binder.

Restoration of the ceiling:
The main problem in the restoration of the ceiling was caused by an extensive crack, triggered by instability. Attempts to secure it had been made in the past but the prominent fissure persisted. It was most obvious in the north eastern corner next to the staircase to the upper level. The unstable masonry in the location had to be repeatedly re-grouted.
During the surveys of the ceiling in the lower chapel historically valuable fragments of old mortar with traces of the original laths were discovered. After thorough examination it was decided that the laths were sufficiently stable and only required conservation.

Restoration of stone elements and figurative ornamentation:
Areas which exhibited signs of serious damage were first pre-consolidated using organo silicate consolidates. Surfaces were then rid of dust deposits. The possible methods of cleaning were carefully evaluated and tested to prevent any disturbance of the stone. The restorers decided to use a regulated steam jet followed by a mechanical finish. In the case of the figurative ornamentation, warm water with suitable detergents was used. Any secondary coatings were removed using ammonium carbonate wraps.
All cracks were infilled and any disturbed areas conserved. Sculptural retouching and infills were coated with a mineral compound tinted with iron oxides. Consolidates based on organosilicate resin were applied where reinforcement was required.
All sculptural retouching was kept to a minimum and was only carried out on the window in the east façade, where missing parts were replaced by a mineral-based material. Other figurative ornamentation was merely conserved.

Original flooring:
The floor of the main areas of the lower chapel was made from flagstones, which were dismantled during the restoration. Once the backfill was removed the original square-shaped fired clay tiling was uncovered. The tiles were cleaned and pre-consolidated using organosilicate resin. As the tiles were in a very poor shape, repeated consolidation using a combination of acrylic and organosilicate consolidates was necessary.
The renovated floor tiles were deemed by the restorers as unsuitable for day-to-day use. Despite the high quality of the restoration work the tiles could not withstand the high level of visitor traffic to the chapel and were replaced by copies, with the originals transferred for safe-keeping.

Stability support of the interior of the upper chapel:
Stability of the interior was ensured by installation of transverse draw bars located below the level of the restored flooring. Loosened parts of the vaulting were reinforced by insertions of wedges.
Restoration of plastering in the interior of the upper chapel:
Restoration work here focused on removal of unsuitable modern so-called droplet plaster, which is generally used to achieve a contrasting appearance against smooth plaster. The droplet texture is produced when a thinned mortar is allowed to drift down the surface of the wall.
The work was concluded by re-grouting and conservation of the original pointing which creates an illusory stone block effect.

Solution to climate control in the chapel:
A suitable solution to the problem of high levels of dampness in the masonry had to be found. Surveys established two factors as the cause: rising damp and condensation. To a lesser degree the present damp was also a result of leaking rain water, which is not led away from the building by gutters.
The dampness degraded both the plastering and the mortar of the foundation masonry and for this reason it was necessary to work out a plan of building alterations which would secure the optimum climate control in the lower part of the chapel. A system of ventilation ducts was devised, which will, together with measures implemented on the perimeter surface of the chapel, improve the overall climactic condition within its interior.