Brick ceilings consist of a load-bearing reinforced concrete structure, the spaces between which are filled with bricks. They are prefabricated slabs and are used in particular in residential construction, commercial buildings and agricultural buildings, but also in the renovation of old buildings. There are brick element slabs, which are delivered to the construction site in large-scale elements, and brick suspended ceilings, in which the bricks are placed individually on site between the load-bearing precast girders made of reinforced concrete.
In addition to its good thermal insulation properties and good eco-balance, brick as a natural building material also has the ability to have a positive effect on the indoor climate. In contrast to concrete, it is able to absorb excess humidity from the air and release it again when needed.
While the reinforced concrete ceiling offers clear advantages from a structural point of view, e.g. larger possible span, higher load-bearing capacity and better sound insulation, the brick ceiling offers the great advantage of low weight. Especially in the renovation of old buildings, brick suspended ceilings are therefore often used as a substitute for wooden beam ceilings. The limited load-bearing capacity of existing walls can also rule out a reinforced concrete ceiling. The simple installation without lifting equipment, often through windows and at your own expense, also speaks in favour of brick suspended ceilings.
While a brick ceiling can be flexibly adapted to the planning and local conditions in a new building, structural difficulties can arise during later conversions. Subsequent relocation of partition walls is very difficult if the brick ceiling was installed without a static concrete layer or without statically cooperating ceiling tiles.
Structural design: Stability calculations are carried out in accordance with Eurocode 2, and the building authority approvals for reinforced concrete girders also apply. Precast plants usually prepare the static calculations in cooperation with the structural engineer of the building. The slab will be delivered with an assembly and possibly reinforcement plan for a concrete layer. The load-bearing capacity tables for brick element ceilings and brick suspended ceilings prepared by the Brick Ceiling Working Group allow simple pre-dimensioning to be carried out in advance, e.g. by the architect.
Installation cables: Installation cables are rarely laid within brick ceilings. Empty conduits for electrics, data cables, heating pipes, etc. above the ceiling in the impact sound insulation or in the screed, or in a suspended ceiling below the brick ceiling are common. Installation in a thicker layer of concrete or in a grouting joint is also conceivable in principle, but must be approved by the structural engineer. In the direction of tension, cable routing is also possible along the continuous cavities of the ceiling tiles .
Loads on the underside of the ceiling: It is possible to attach suspended ceilings or other loads to a brick ceiling underneath, but these loads should be included in the planning at an early stage. While some manufacturers only allow attachment in the middle of the ceiling beam by means of expansion plugs, others also allow attachment to metal strips, which are put over the beams from above during installation in suspended ceilings and protrude downwards from the ceiling.
For fixings in the ceiling tile , injection dowel systems are generally used. Their load capacity is in the range of approx. 30 kg (just under 0.3 kN as a point load). In any case, the planner should coordinate with the respective ceiling manufacturer in advance.
Fire protection: Like steel and concrete, brick is a non-combustible building material of class A1 according to DIN EN 13501-1. A brick ceiling thus offers the best conditions for optimal fire protection if it is sufficiently dimensioned and concrete covered , see the lexicon article on fire behaviour, class according to DIN EN 13501-1. In the technical data sheets, the manufacturers also provide information on the fire resistance of the entire component.
Sound insulation: The protection goals in terms of noise protection must be determined in advance between the planner and the client, as several sets of regulations exist side by side. Especially in residential buildings with several units, high requirements apply according to the state of the art, which in particular concern the sound transmission between the units, i.e. also the transmission via false ceilings. DIN 4109 regulates the absolute minimum standard, which is considered outdated today. Planners should use the increased values according to DIN 4109 Supplement 2 or VDI guideline 4100 as a basis as a minimum standard. The DEGA Recommendation 103, which was prepared by the German Society for Acoustics e.V., can also be used for orientation in order to improve sound insulation beyond the binding standards by dividing it into sound insulation classes (regardless of the building construction).
The protection against airborne noise increases with the increase in the area-related mass of a ceiling tile, which is determined by the thickness and bulk density of a component. Since brick as a building material is inferior to that of reinforced concrete in terms of sound insulation, the insulation value increases with the increase in the proportion of reinforced concrete or with the introduction of a concrete layer. For acoustic decoupling via the side walls, a layer of bitumen board, for example, must be provided in the support area under and above the brick ceiling.
An improvement in impact sound insulation is hardly achieved by increasing the area-related mass. A double-shell construction is far more effective in this respect. Floating screed is particularly effective as a second shell. It is acoustically decoupled from the ceiling and wall construction by impact sound insulation and edge insulation strips, see bauwion page ►400 | Construction site screeds.
In general, brick ceiling manufacturers provide accurate information on sound insulation value R'w and standard impact sound level L'n, w of their products.
Thermal insulation: Brick ceilings that separate heated interiors from outdoor spaces (e.g. passageways, flat roofs) must be insulated in accordance with the Energy Saving Ordinance. Since brick ceilings are always manufactured in conjunction with reinforced concrete components, additional thermal insulation is usually necessary to avoid thermal bridges .
In the case of ceilings against rooms that are included in the calculation as unheated or are not within the system boundary of the heated building volume (e.g. unheated basement or attic space), it must be checked whether the insulation value of the ceiling is sufficient, otherwise condensation cannot be ruled out.
Thermal insulation can only be dispensed with in well-ventilated rooms above and below the ceiling (e.g. two levels of an open underground car park) and in ceilings that only separate heated rooms from each other.
A brick ceiling can reduce the cross-section of an exterior wall if it serves as a support. The grouting component on the edge of the ceiling can create thermal bridges here , which then have to be compensated for by inserting insulation strips.
Ecology: The starting materials for the production of bricks are clayey clays and water, i.e. natural materials without the addition of chemical additives. The energy used for production is relatively low, and disposal is unproblematic. Thus, bricks in their original form have a good ecological balance. However, in the overall assessment of a brick ceiling, the proportion of reinforced concrete must also be taken into account.
Special forms:
Brick climate ceiling: The climate ceiling is one of the brick element ceilings. The underside of the ceiling acts as a radiant surface of cold or heat for the room below. The heating and cooling pipes are integrated into the specially shaped ceiling tiles . They are located directly under the ceiling plaster and can be adjusted as required.
Solid tile roof: In terms of building physics and building biology, a solid tile roof offers the advantages of a brick wall, whereby the good heat storage capacity, heat and sound insulation are particularly important under the roof in order to increase the quality of the living space below. From a structural point of view, the solid tile roof is to be understood as a variant of the brick element ceiling or the brick suspended ceiling. The roof elements are used either in rafter construction (tensioning direction from ridge to eaves) or bulkhead construction (tensioning direction parallel to the ridge). The manufacturers of tiled roofs are prepared to produce all common roof shapes , including the associated special shapes, such as dormers.
Brick wooden beam ceiling: A variant of the brick suspension ceiling is the brick wooden beam ceiling, in which the reinforced concrete beams are replaced by wooden beams. While the ceiling soffit is given further design options by a visible beam layer, the brick ceiling is given an additional ecological upgrade by using wood as a material and by largely avoiding reinforced concrete .
of brick ceilings: Prefabricated elements are manufactured in the factory according to submitted execution plans and statics. When delivered to the construction site, a laying plan with detailed assembly instructions is usually included.
Until installation, all ceiling supports must be created by mortar at the exact height and fully load-bearing. The flatness and cleanliness of the supports is also important here in order to enable the elements to be supported over the entire surface. A layer of bitumen cardboard serves as an intermediate layer. As a rule, brick prefabricated ceilings do not require any assembly support. Only in the area of beams, roller shutter boxes and lintels is the ceiling to be supported with edge yokes. In the case of suspended ceilings, linear assembly support is necessary. The type and location of the mounting support is specified in the assembly instructions.
The elements are lifted onto the prepared supports with a crane or truck-mounted crane, usually without intermediate storage. Ceilings without a concrete layer can be walked on and loaded immediately, and the pouring of the individual elements can be started immediately. Circumferential ring anchors or similar are also encapsulated in the same operation. In the case of slabs with a concrete layer, upper reinforcement may have to be installed before concreting the concrete layer.
Reinforcement: In the case of precast slabs, the reinforcement is already installed and monitored in the precast plant. When grouting the joints, beams and ring anchors on site, it may be necessary to insert additional reinforcing bars according to the assembly plan or statics. The installation of upper reinforcement is also required for slabs that require a strong concrete layer. When installing this reinforcement on the construction site, care must be taken to ensure compliance with the required concrete covers. Otherwise, the reinforcement can corrode over the years and, in extreme cases (e.g. in the event of a fire), the structure can no longer meet its static requirements.
Joint grouting / concrete layer: Brick surfaces that come into contact with the concrete must be well pre-wetted immediately before the concrete is laid. Subsequently, the delivered or locally produced concrete must be installed as quickly as possible. This must prevent cavities from forming in the component. This is prevented by shaking, stomping or poking. However, if this is done for too long, there is a risk of segregation. This is shown by the formation of an aqueous sludge layer on the surface.
The concrete should always be applied in layers for deep joints and thicker layers. The installation must also not be carried out from a drop height of more than two metres.
In extreme climatic conditions such as heat (over 30°C) or frost (below -5°C), concrete may not be poured without suitable additional measures.
DIN 488-2, Reinforcing Steel - Reinforcing Bar
DIN 488-3, Reinforcing Steel in Rings, Reinforcing Wire
DIN 1045-2, Supporting Structures of Concrete, Reinforced Concrete and Prestressed Concrete - Part 2: Concrete - Specification, Properties, Production and Conformity - Rules of Application for DIN EN 206-1
DIN 1045-100, Design and Construction of Reinforced Concrete and Prestressed Concrete Structures - Part 100: Brick Ceilings
DIN 4109, Sound Insulation in Building Construction; Requirements and verifications
DIN 4109 Supplement 2, Sound insulation in building construction; Instructions for planning and execution; proposals for increased sound insulation; Recommendations for sound insulation in one's own living or working area
DIN 4159, Bricks for brick ceilings and grouting panels, statically contributing
DIN 20000-129, Application of building products in buildings, Part 129: Rules for the use of ceramic intermediate components according to DIN EN 15037-3
DIN EN 206, Concrete - Specification, properties, production and conformity
DIN EN 1992-1-1, Eurocode 2: Design and construction of reinforced concrete and prestressed concrete structures - Part 1-1: General design rules and rules for building construction
DIN EN 1992-1-1/NA, National Annex - Nationally determined parameters - Eurocode 2: Design and construction of reinforced concrete and prestressed concrete structures - Part 1-1: General design rules and rules for building construction
DIN EN 1992-1-1/NA/A1, National Annex - Nationally Determined Parameters - Eurocode 2: Design and Construction of Reinforced Concrete and Prestressed Concrete Structures - Part 1-1: General Design Rules and Rules for Building Construction, Amendment 1
DIN EN 1992-1-2, Eurocode 2: Design and Construction of Reinforced Concrete and Prestressed Concrete Structures - Part 1-2: General Rules - Structural Design for Fire
DIN EN 1992-1-2/NA, National Annex - Nationally defined parameters - Eurocode 2: Design and construction of reinforced concrete and prestressed concrete structures - Part 1-2: General rules - Structural design for fire
DIN EN 13501-1, Classification of construction products and construction methods with regard to their reaction to fire Part 1: Classification with the results of the tests on the reaction to fire of construction products
DIN EN 15037-1, Precast concrete elements - Beam slabs with intermediate components - Part 1: Beams
DIN EN 15037-3, Precast concrete elements - Beam ceilings with intermediate components - Part 3: Ceramic intermediate components
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Source: bauwion
