The insulation of components in contact with the ground on their outside is called perimeter insulation and is always located outside the waterproofing of a building. Particularly high demands are placed on perimeter insulation, as it is directly adjacent to the ground and is thus exposed to pressure, moisture, chemical effects and possibly influences from traffic loads. Therefore, perimeter insulation is pressure-resistant, rot-resistant and does not absorb moisture (or only to a small extent).
Only the highest quality insulation materials are used as perimeter insulation. At the latest since the introduction of the EnEV (Energy Saving Ordinance), basements that have not been converted into high-quality usable areas have also been thermally insulated, as the basements are usually included in the heat envelope. However, unheated cellars outside the system boundary of the heat envelope should also be insulated in order to avoid building physics problems such as condensation and the resulting mould formation.
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Important: The load case soil moisture and non-accumulating water must always be assumed as a minimum requirement for all building waterproofing, unless there are further requirements. The decision-making bases listed in the matrix can be determined by a geotechnical report in accordance with DIN 4020.
Choosing the right insulation material: With the help of the table above, the right insulation material can be selected depending on the existing soil, the various water effects and the installation depth. The thermal insulation of the basement walls only works well if no cold groundwater or strata water can penetrate between the panel joints to the shell basement wall. Products with a rebate or tongue and groove system have advantages in this respect.
Approval: The use of XPS (extruded polystyrene) and foam glass as perimeter insulation is regulated in DIN 4108-2 as a standardised construction. On the other hand, the use of EPS (expanded polystyrene) and PUR (polyurethane) must be regulated and proven by building authority approvals. For use in the area of pressurized water, all products must have building authority approvals.
Arrangement: Perimeter insulation is always placed outside the external waterproofing of the building (e.g. thick coating). The perimeter insulation thus also serves to protect the seal from mechanical damage.
Transition to the floor slab: In high-quality insulated buildings, the perimeter insulation should also cover the front side of the floor slab, including the floor slab projection.
Application for pressurized water/groundwater: For use in the area of pressurized water or groundwater, only XPS insulation materials or foam glass insulation are permitted. Proof of buoyancy protection must be provided for both. The buoyancy forces must not be introduced into the structure via the waterproofing. In the case of basement walls made of waterproof concrete (► tub, white), no buoyancy protection is necessary. Proof of buoyancy protection is deemed to have been provided if one of the following points is complied with:
Connection of basement windows: In the connection area of basement windows, care must be taken to ensure that the design is free of thermal bridges as early as the planning stage. System basement windows have integrated reveal variants to choose from. When installing conventional windows, the connection must be planned in detail. For example, when forming the walls, a strip of perimeter insulation can be inserted into the formwork around the window. Alternatively, the window frame can be insulated with perimeter insulation.
Protection: Perimeter insulation can be protected from mechanical damage with a studded membrane, especially when backfilling the excavation pit. However, the use of a dimpled membrane is only absolutely necessary if protection against mechanical damage cannot otherwise be ensured.
: The manufacturer's specifications for installation must be observed, especially with regard to the condition of the substrate, fastening, panel joints and weather conditions. The panels are glued together with staggered joints. Cross impacts are to be avoided.
Installation EPS, XPS and PUR: The insulation boards are bonded either with construction adhesive or with bituminous waterproofing compound (e.g. thick coating). In groundwater or in the area of pressurized water, it is necessary to bond the panels and panel edges over the entire surface as well as to fill the slab joints. The perimeter insulation can be glued to the basement wall with a thick coating. If the thick coating is also used as a seal in accordance with DIN 18195, it is essential to ensure that the thick coating is applied and dried beforehand in a sufficient minimum layer thickness (3 mm or 4 mm).
Installation of foam glass: Foam glass panels must be glued completely and over a large area with a bitumen adhesive. The surfaces of the laid panels must be provided with a bituminous, frost-resistant coating over the entire surface.
Panel rebate: When installing, make sure that the rebate of the panel joints is installed the right way around . The rebate is to be arranged in such a way that water penetrating away from the structure is directed to the outside.
Multi-layer installation: Only XPS insulation can also be installed in several layers, taking into account the manufacturer's specifications. The slab layers must be glued together and joint-covered and staggered.
Insulation of the floor slab overhang: various manufacturers offer system components made of perimeter insulation materials, which function simultaneously as edge formwork of the floor slab and perimeter insulation of the floor slab overhang.
Perimeter insulation as slab edge formwork: Perimeter insulation should not be used as edge formwork for the basement ceiling - as is widespread in practice - if it is located in the waterproofing area, otherwise no waterproofing can be applied to the front of the basement ceiling. Accordingly, the waterproofing and perimeter insulation should only be applied after the basement ceiling has been completed and switched off.
Protection: Perimeter insulation should not be permanently exposed to solar radiation. Insulation must be covered, especially in the plinth area and in light shafts, e.g. with a layer of plaster, sheet metal or studded membrane.
Special feature of foam glass insulation boards: They must be protected against frost damage up to frost depth with a frost-resistant filler at least 2 mm thick. Alternatively, manufacturers offer so-called boards. These are glued together at the factory from several foam glass insulation boards with a bitumen lamination to form large-format boards. They do not require an additional layer of antifreeze.
Note: DIN 4108-1 (Thermal insulation in building construction; Sizes and units) has been withdrawn and replaced by DIN EN ISO 7345
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 4108-10, Thermal insulation and energy saving in buildings - Part 10: Application-related requirements for thermal insulation materials - Factory-made thermal insulation materials
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, 1955-07, Scale of measurement in building construction
DIN EN 13163, Thermal insulation products for buildings — Factory-made products made of expanded polystyrene (EPS) — Specification
DIN EN 13164, Thermal insulation products for buildings — Factory-made products as extruded polystyrene foam (XPS) — Specification
DIN EN 13165, Thermal insulation products for buildings — Factory-made products made of rigid polyurethane foam (PU) — Specification
DIN EN 13167, Thermal insulation products for buildings — Factory-made products made of foam glass (CG) — Specification
EnEV - Energy Saving Ordinance for Buildings, Ordinance on Energy-Saving Thermal Insulation and Energy-Saving Plant Technology for Buildings
►Fact sheet Thermal insulation of components in contact with the ground from the Polystyrene Extruder Foam
Thermal Protection of Components in Contact with the Earth (Perimeter Insulation), Merkel, H. – Insulation materials, stresses, constructions. Building Physics Calendar 2002, Verlag Ernst & Sohn, Berlin 2002
Source: bauwion
