In the case of exterior walls, sand-lime brick is usually used as the inner shell of a multi-layer exterior wall with external insulation (e.g. in the case of a VHF or an ETICS). Compared to other masonry materials, sand-lime brick is characterised by its particularly high bulk density. As a result, masonry made of sand-lime brick has excellent static properties, offers high sound insulation values and a high heat storage capacity. Characteristic of masonry blocks made of sand-lime brick is their rectangular, sharp-edged basic shape.
Image: Example "KS-Ratio-Plansteine" - KS-ORIGINAL GMBH
Wall construction: Due to the high density and the resulting high heat transmittance of sand-lime bricks, exterior walls of heated buildings are built in several layers. These so-called functional walls have the advantage that the inner load-bearing and heavy layer of sand-lime brick takes over all requirements for statics, fire protection, sound insulation and summer thermal insulation. The outer layer of lightweight insulation materials and cladding, on the other hand, provides winter thermal protection and weather protection. This specialisation of the individual layers creates wall structures that can be optimally adapted to all requirements. The outer skin can be designed, for example, as a thermal insulation composite system (ETICS), as a rear-ventilated façade (VHF) or as visible facing masonry with core insulation.
planning thermal insulation: The design values for walls made of sand-lime brick are in the range between λ= 0.7 - 1.3 W/mK, so that an exterior wall for heated rooms according to the current EnEV standard requires additional insulation measures. Due to the high thermal conductivity of sand-lime bricks, thermal bridges also have a particularly harmful effect and thus require particularly conscientious planning of connections and transitions to adjacent components.
Fire protection: Sand-lime brick walls are non-combustible and comply with building material class A1 according to DIN 4102-4, i.e. they have excellent fire protection properties. The design of a fire wall is possible with a flat block of the bulk density class ≥1.8 kg/dm³ with a wall 17.5 cm thick.
Statics: The high stone compressive strength (SFK) gives sand-lime brick walls good static properties, they are highly resilient. For example, load-bearing walls are already possible with a wall thickness of 11.5 cm, but wall thicknesses of at least 15 cm are common for load-bearing walls. With load-bearing outer walls with a wall thickness of 36.5 cm made of sand-lime brick, buildings with up to 10 floors can be built.
Sound insulation: Due to its high bulk density , sand-lime brick is predestined for walls with increased sound insulation requirements. For more information, see also encyclopedia article ► Sand-lime brick walls, sound insulation
Masonry dimensions: Despite the high-quality equipment of most construction companies with cutting equipment, it still makes sense to take the masonry dimensions into account as far as possible in the planning for an economical execution. These are regulated in DIN 4172 and are based on a grid of 12.5 cm = octametric system (see ► Masonry dimensions in the lexicon).
Doors and windows: The opening dimensions of doors and windows must be determined in the implementation planning for the shell construction, depending on the door and window systems to be executed. For example, in the case of an interior door, the design of a perimeter frame requires a different shell dimension than the design as a block frame or as a bolt-stick element with similar passage clearances.
Vapour diffusion: Depending on their bulk density , sand-lime brick walls have a water vapour diffusion resistance coefficient μ approx. 5 to 25 and thus an average vapour permeability. They are therefore considered a wall construction that is open to diffusion. Any type of outer skin should therefore either be rear-ventilated or also designed to be diffusion-open.
Ecology: Sand-lime brick walls have a good eco-balance, they are produced only from the natural materials sand, lime and water. No chemical additives are added, and there are no environmentally harmful residues. The energy required during production is low. However, the life cycle assessment of an exterior wall made of sand-lime brick depends on the additional outer skin applied, which is indispensable for sand-lime brick walls as a component of heat-insulating exterior walls.
Special components: A large number of supplementary products are offered as a supplement to the wall blocks. These include, for example, compensating stones (chine stones) for height compensation at the foot or head of the wall, lintels, belt winding stones and U-shells. Chinets are also available with a significantly improved thermal insulation value due to integrated thermal insulation, so that a thermal separation between the wall and the floor slab or ceiling can be achieved.
Legally binding nature of DIN "V" 106: Despite its character as a "pre-standard", DIN V 106 is published in most German federal states via the respective list of technical building regulations, thus introduced by the building authorities, and must therefore be observed by all parties involved in the planning and execution of structural facilities.
and approval: Sand-lime bricks can be used as a regulated or non-regulated building product. They are classified as a regulated construction product in accordance with the Building Rules List A Part 1 if they comply with DIN EN 771-2 (Specifications for masonry blocks - Part 2: Sand-lime bricks) and there are no significant deviations from DIN V 106 (Sand-lime bricks with special properties), Section 4.8 as a technical rule. Only in this case can DIN V 106 be used as proof of usability. Compliance with the technical rule is confirmed by the manufacturer in the form of a corresponding declaration of conformity for these products. In accordance with DIN V 106, chamfer stones generally require general building authority approval (abZ) if they are to be used as load-bearing masonry. For all other masonry blocks made of sand-lime bricks that do not have a declaration of conformity from the manufacturer as a regulated construction product, proof of usability in the form of a general building authority approval (AbZ) is usually required. This is not necessary if the user (planner or contractor) of stones that are (only) marked with the CE mark can prove on his own responsibility (!) on the basis of DIN 20000-402 that they meet the characteristics of DIN V 106. For masonry in accordance with DIN EN 1996-1-1/NA, only sand-lime bricks of category I according to DIN EN 771-2 with a declared compressive strength may be used in Germany.
Laying of walls: Before the first row of stones is placed, a horizontal seal against rising damp and a levelling layer of normal mortar of mortar group III with a thickness of 1 to 3 cm are applied to the ceiling or floor slab. This serves to compensate for unevenness.
Bearing joints: In the case of "normal" bricks, approx. 10 to 12 mm thick bearing joints made of normal mortar are applied with the mortar carriage or trowel. Flat stones and plan elements are mixed with thin-bed mortar only a few millimetres thick. The application is carried out with thin-bed mortar slides or planks. After stiffening the mortar, overflowing mortar must be removed with the spatula.
Butt joints: Sand-lime bricks are often produced with tongue and groove systems, these are declared with -R. In these cases, butt joint masonry can usually be omitted. However, additional mortar in the corner area of walls reduces the risk of cracking and forms a force-fit connection.
Waiting times: Experience has shown that the majority of the regular changes in the shape of a shell take place in the first weeks and months. Accordingly, a waiting period of approx. 6 months before plastering is recommended to avoid cracks.
Weather influences: If the heat is too strong, the stones should be wetted to prevent the mortar from being absorbed too quickly into the absorbent stone. In the same way, the masonry must be protected from frost and heavy moisture penetration. The construction of masonry with frozen building materials is not permitted. Exposed window sills or masonry that is open at the top should be covered with slabs or tarpaulins to prevent precipitation moisture from penetrating the masonry.
Note: The DIN 1053 series of masonry standards has been withdrawn with the exception of the revised DIN 1053-4 (prefabricated components). Its successors are the Eurocode standards of the DIN EN 1996 series. Although DIN 1053-1 (calculation and execution) has also been withdrawn by the Standards Institute, it is still valid until the end of 2015 via the building regulations in Germany. Their application is possible as an alternative to the regulations of Eurocode 6, but may not be mixed with them.
Note: DIN 4108-1 (Thermal insulation in building construction; Sizes and Units) has been withdrawn and replaced by DIN EN ISO 7345.
DIN 1053-1, Masonry - Part 1: Calculation and execution
DIN 4108 Supplement 2, Thermal insulation and energy saving in buildings - Thermal bridges - Planning and execution examples
DIN 4108-2, Thermal insulation and energy saving in buildings - Part 2: Minimum requirements for thermal insulation
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 4109/A1, Sound insulation in building construction - requirements and verifications; Amendment A1
DIN 4172, Measurement Regulations in Building Construction
DIN V 106, Pre-Standard, Sand-lime Bricks with Special Properties
DIN 20000-402, Application of Construction Products in Buildings - Part 402: Rules for the Use of Sand-Lime Bricks according to DIN EN 771-2:2005-05
DIN EN 771-2, Specifications for Masonry Bricks - Part 2: Sand-lime Bricks
DIN EN 1996-1-1, Eurocode 6: Design and construction of masonry structures - Part 1-1: General rules for reinforced and unreinforced masonry
DIN EN 1996-1-1/NA, National Annex - Nationally determined parameters - Eurocode 6: Design and construction of masonry structures - Part 1-1: General rules for reinforced and unreinforced masonry
DIN EN 1996-1-1/NA/A1, National Annex - Nationally Determined Parameters - Eurocode 6: Design and Construction of Masonry Structures - Part 1-1: General Rules for Reinforced and Unreinforced Masonry; Amendment A1
DIN EN 1996-1-2, Eurocode 6: Design and construction of masonry structures - Part 1-2: General rules - Structural design for fire
DIN EN 1996-1-2/NA, National Annex - Nationally defined parameters - Eurocode 6: Design and construction of masonry structures - Part 1-2: General rules - Structural design for fire
DIN EN 1996-2, Eurocode 6: Design and construction of masonry structures - Part 2: Planning, selection of building materials and execution of masonry
DIN EN 1996-2/NA, National Annex - Nationally defined parameters - Eurocode 6: Design and construction of masonry structures - Part 2: Planning, selection of building materials and execution of masonry
DIN EN 1996-3, Eurocode 6: Design and construction of masonry structures - Part 3: Simplified calculation methods for unreinforced masonry structures
DIN EN 1996-3/NA, National Annex - Nationally determined parameters - Eurocode 6: Design and construction of masonry structures - Part 3: Simplified calculation methods for unreinforced masonry structures
DIN EN 1996-3/NA/A1,National Annex - Nationally Determined Parameters - Eurocode 6: Design and Construction of Masonry Structures - Part 3: Simplified Calculation Methods for Unreinforced Masonry Structures; Amendment 1
DIN EN ISO 7345, Thermal insulation - Physical quantities and definitions
EnEV - Energy Saving Ordinance for Buildings, Ordinance on Energy-Saving Thermal Insulation and Energy-Saving System Technology for Buildings
Masonry Atlas, the Construction of Supporting Structure and Building Envelope, Günter Pfeifer, Rolf Ramcke, Joachim Achtziger, Konrad Zilch, 2001
►Bundesverband Kalksandsteinindustrie e.V. Facts, knowledge and working aids, Numerous downloads, including KS sound insulation calculator
Source: bauwion
