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Building with EPS (SANS 204) | Products
Home → EPS User Guides → Building with EPS (SANS 204) Introducing EPS
This document will guide the user in accordance with the requirements of SANS 204 Energy efficiency in buildings, with specific focus on the usage and application of Expanded Polystyrene (EPS) in floors, walls and roofs.
1. Definitions, Interpretation & TerminologyBUILDING ELEMENT
Wall, floor, foundation or roof of a building.
The elements of a building that separate a habitable room from the exterior of a building or a garage or storage area.Note: The envelope controls heat gain in summer and heat loss in winter. Well-designed envelopes maximize cooling air movement and limit exposure to direct sunlight in summer. In winter, they trap and store heat from the sun and minimize heat loss to the external environment. The fundamental principles of passive design should be applied to a vast range of building types and construction systems in the various South African climates.
Materials of low thermal conductivity, that mainly resist (slows) the transfer of conducted and convected heat (due to theirthickness), relying on pockets of trapped air or low conductive gasses within its structure. Note: The thermal resistance is essentially the same regardless of the direction of heat flow through it and is proportional to its thickness, density and upper & lower operating temperature.
Region in which the climatic conditions are similar. Note: The zones have been adjusted to simplify use of the energy efficiency measures. A map of South Africa indicating the various climatic zones and a table specifying the zones for major cities and towns on the borders of climatic zones is given in chapter 5.
Thermal capacity (kJ/m²·K) of a material, which is the ability to store heat energy, and is the arithmetical product of specific heat capacity (kJ/kg·K), density (kg/m3) and thickness (m).
Time constant (hours) of a composite element, such as a wall, and being the arithmetical product of total C-Value and the total R-Value. Note: The higher the CR-Value the greater the ability of the composite element to moderate and minimise the effects of external climatic conditions on the interior of a building.
Two or more types of material combined to achieve a required level of performance, example: bulk insulation and reflective insulation used in combination.
DEEMED-TO-SATISFY REQUIREMENT
Non-mandatory requirement, the compliance which will ensure compliance with a functional regulation.
The mass of a substance per unit of volume. SI unit of measure is kg/m³.
Most significant heat flow at a given time. Note: Heat flow from hot to cold environments is considered to be the direction of natural heat flow. Therefore “upwards” implies heat flow from a conditioned space through the ceiling or roof, and “downwards” implies the opposite. Likewise,
horizontal flows can be described as “inwards” and “outwards”.
Minimizing energy consumption while still achieving the required output.
Note: In the context of buildings this will be the maintenance of required indoor comfort conditions and the provision of necessary power for correct operation of all installed services. Designing for energy efficiency involves the design, selection of materials, components and systems to minimize energy consumption. Achieving energy efficiency involves design, operation, maintenance and on-going adjustments to minimize energy consumption.
External thermal insulation composite systems.
Complete walling system, as measured from the outer skin exposed to the environment, to the inside of the inner skin exposed to the interior of the building, and does not include glazing.
Particular use or the type of use to which a building or portion thereof is normally put or intended to be put. Note: Regulation A20 classifies and designates occupancies (see SANS 10400 Part A).
Roofing or ceiling system (or both), as measured from the outer skin exposed to the environment, to the inside of the inner skin exposed to the interior of the building, and does not include glazing such as roof lights and skylights
The thermal resistance (m2.K/W) of a component (see Thermal Resistance) The measurement of the thermal resistance of a material which is the effectiveness of the material to resist the flow of heat, i.e. the thermal resistance (m².K/W) of a component calculated by dividing its thickness by its thermal conductivity.
Structural Insulated Panel Systems.
Ability of a material to store heat energy. Note: Thermal capacity is measured as a C-Value; the higher the C-Value the greater the heat storing capability.
An element of low thermal conductivity placed in an assembly to reduce or prevent the flow of thermal energy (transfer of heat) from one component to another.
THERMAL CALCULATION METHOD (BY MATHEMATICAL ANALYSES)
A means of calculating the cooling and heating loads of the cooling and heating systems.
THERMAL CONDUCTANCE – SYMBOL (“C”)
A measure of the ability of a substance or material to conduct heat, i.e. the transfer of heat through a solid (material) and the unit is W/K.
Note: When one end of a metal rod (poker) is left in a fire the opposite end will also become warm although not in direct contact with the flame.
The flow of heat along the length of the rod is by conduction. The rate of heat (energy) flow is influenced by the temperature difference between one side and the opposite side e.g. indoor to outdoor, the area of the material mass, the distance (thickness) through the material from warm side to cool side, and the thermal conductivity of the material. Most insulating materials (mass type) have low thermal conductivity, which combined with their thickness, density and the operating temperature provides a barrier that reduces conductive heat transfer.
THERMAL CONDUCTIVITY – SYMBOL “K”
The thermal transmission through a unit area of a material. It is measured per unit temperature difference between the hot and cold faces, and the unit is W/(m.K).
1) It is the rate of heat flow through a unit area (1m²) of 1 metre thick homogenous material in a direction perpendicular to isothermal planes; induced by a unit temperature gradient viz 1 metre cube of material will transmit heat at a rate of 1 watt for every degree of temperature difference between opposite faces.
2) A “k” value cannot be given for Reflective Sheet Insulation as these are highly dependable upon orientation and position of surrounding air spaces. The heat flow across an air space is not directly proportional to its thickness. Variations in direction of heat flow, the position of the air space (viz horizontal, vertical, etc.) and variance in mean temperature etc., affects the thermal resistance of the system.
The ability of building materials to store heat. The basic characteristic of materials with thermal mass is their ability to absorb heat, store it, and at a later time release it. Note: By adding thermal mass within the insulated building envelope it helps to reduce the extremes in temperature
experienced inside the home/building, making the average internal temperature more moderate year-round and the home/ building more comfortable. Building materials that are heavyweight store a lot of heat and have high thermal mass. Materials that are lightweight do not store much heat and have low thermal mass. The use of heavyweight construction materials with high thermal mass (concrete slab on ground and insulated brick cavity
walls) can reduce total heating and cooling energy requirements compared to a home built of lightweight construction
materials with a low thermal mass (brick veneer with timber floor).
THERMAL RESISTANCE – SYMBOL “R-VALUE”
The resistance to heat transfer across a material. It is the mean temperature difference between two defined surfaces of a
material or construction system under steady state conditions. Note: Thermal resistance is measured as an R-Value. The higher the R-Value the better the ability of the material to resist heat flow it is measured in m².K/W.
TOTAL C-VALUE
Sum of the C-Values of the individual component layers in a composite element including the air space.
The sum of the R-Values of all the individual component layers in a composite element including the air space and associated surface resistances measured in m².K/W.
TOTAL U-VALUE
The thermal transmittance (W/m².K) of the composite element including the air space and associated surface transmittance.
1) The U-Value addresses the ability of a material to conduct heat, while the R-Value measures the ability to resist heat flow.
The higher the U-Value number, the greater the amount of heat that can pass through that material. A lower value would mean
a better insulator.
2. Material Properties2.1 EPS CLASSIFICATION
There are three main types of rigid foam insulation products currently being used in the building industry: Expanded Polystyrene (EPS), Extruded Polystyrene (XPS), and Polyisocyanurate (PIC). Each of these products has a different set of physical properties. Insulating foam boards are split into two basic categories: thermoplastics and thermosets, both EPS and XPS foams are thermoplastic foams, while Polyisocyanurate is thermoset foam.
EPS Product Classification (types) EPS-Products are divided into types as shown in Table 1 and 2. Type EPS T has specific impact sound insulation properties. Each type, except EPS S, which is not used in load bearing applications, shall satisfy two different conditions at the same time in order to ensure adequate product performance.
TABLE 1 Classification of EPS Products (EN 13163)
TABLE 2 Classification of load bearing EPS products with acoustical properties
2.2 WHAT IS EPS?
Expanded Polystyrene, or EPS for short, is a lightweight, rigid, plastic foam insulation material produced from solid beads of polystyrene. Expansion is achieved by virtue of small amounts of pentane gas dissolved into the polystyrene base material during production. The gas expands under the action of heat, applied as steam, to form perfectly closed cells of EPS. These cells occupy approximately 40 times the volume of the original polystyrene bead. The EPS beads are then moulded into appropriate forms suited to their application.
2.3 EPS TYPES & PROPERTIES
The properties of EPS Insulation materials for buildings and their test methods are defined in EN 13163 Thermal insulation products for buildings – Factory made products of expanded polystyrene (EPS) – specification, a standard which EPSASA has been using as a guideline in their testing protocol. According to the EPSASA Testing Protocol the manufacturers are required to test at regular intervals through mandatory testing and to declare the properties of the specific products. Compliance with South African National Building Regulations is based on the performance level of the finished product. An approximate conversion between the EPS types according to EN 13163 based on density is given in the table hereafter.
Each type shall satisfy the different conditions at the same time in order to ensure adequate product performance.
Above grades cover the total building application spectrum. Applications can range from general purpose, floor insulation, wall insulation, roof insulation, ceiling insulation to under roof applications.
2.4 THERMAL RESISTANCE (R-VALUE)
The R-Value of EPS foams can be increased by increasing the density of the product. The thermal resistance of these thermoplastic foams is generally stable over the long term and therefore the initial R-Value at the time of manufacturing will not change over time. In the construction sector, EPS has a long established reputation for its exceptionally high insulation qualities. This means EPS is the perfect choice for use in under-floor, between-floor, walling and roofing applications where it is able to give a constant insulation value across the full service life of the building.
All EPS products, as promoted by EPSASA, fulfil the requirements in accordance with the National Building Regulations
SANS 10400-T Fire Protection.
2.6 WHERE TO USE EPS?
Anyone who needs to thermally insulate walls, roofs or floors will find EPS the ideal, cost-effective and easy-to-use material in all types of buildings, from houses and offices to factories. EPS is used by civil engineers as a lightweight fill or voidforming material. It is also used as a flotation material.
3. Environmental Impacts3.1 ENVIRONMENTAL DEFINITIONS AND UNITS
3.2 EPS AND THE ENVIRONMENT
EPS is non-toxic and totally inert. It contains no Chlorofluorocarbons (CFCs) or Hydrofluorocarbons (HCFCs). It is also absent of any nutritional value, no fungi or micro-organisms can grow within EPS. EPS does not and has never used CFCs or HCFCs in its manufacturing process. Therefore it does not damage the ozone layer. The environmental effects of the manufacture of EPS raw material (expandable polystyrene bead) and its conversion to EPS insulation material are small. Over the life cycle of EPS insulation, the main environmental effects are those of substances released into the atmosphere, principally when the raw EPS is made and when the insulation board is delivered to users. The main substance is pentane (used as blowing agent), which is released during the conversion of the raw material to insulating board, has a minimal global-warming potential making only a slight contribution to the greenhouse effect. Once EPS is installed in a building, emission levels are negligible, due in part to the fact that its volume consists of 98% air.
EPS presents no dangers to health in installation and use. EPS is non-irritant and rot-proof. Fungi and bacteria cannot grow on EPS and it is insoluble and non-hygroscopic. EPS is also rodent-proof and offers no nutrient attraction to vermin. Nor is it affected by water, thus ensuring that moisture contact will not lead to deterioration of the product or its performance. Cement, lime, gypsum, anhydrite and mortar modified by plastics dispersions have no effect on EPS, so it can confidently be used in conjunction with all conventional types of mortar, plaster and concrete encountered in building construction. All of this makes it entirely safe in use across all of its construction applications.
3.4 RECYCLABLE
EPS can be recycled if it is recovered without contamination from other materials. Generally the most beneficial is direct reuse by grinding clean EPS waste and adding it to virgin material during production of new foamed products. Alternatively, EPS can be melted and extruded to make compact polystyrene, for items such as plant pots, coat hangers and a wood substitute. Medium toughened polystyrene from which sheets for thermoformed articles, such as trays, can also be made. As part of mixed plastic waste, EPS can be recycled to make, for example, park benches, fence posts and road signs, ensuring the plastic material has a long and useful second life.
For more information on recyclability visit www.polystyrenepackagng.co.za and www.plasticsinfo.co.za
3.5 LIFE CYCLE ASSESSMENT (LCA) OF EXPANDED POLYSTYRENE
Recent years have shown growing concern for the environment and in particular an increased demand for sustainable building and development. For the construction industry this means a need for accurate information about the environmental impact of the building materials and products that they use. The most reliable way to present this information has proved to be the Life Cycle Assessment (LCA) approach.
An LCA is a tool for assessing and evaluating the environmental impacts of a product or service during its entire life cycle which investigates the processes involved in the manufacture, use and disposal of a product or a system – from ‘cradle to grave’ by:
• Compiling an inventory of relevant inputs and outputs from and to the environment of a system.
• Evaluating the potential environmental impacts associated with those inputs and outputs.
• Interpreting and valuating the results of the inventory and impact phases in relation to the objectives of the study (ISO 1997).
An integral approach is characteristic to the LCA-method. All impacts on the environment are taken into account. The LCA is widely accepted as a method for generating objective and verifiable environmental information.
The International Organisation for Standardisation (ISO) provides guidelines for conducting an LCA within the series ISO 14040 and 14044. The main phases of an LCA are:
• Goal & Scope definition, the product or service to be assessed is defined, a functional basis for comparison is chosen and the required level of detail is defined.
• Inventory analysis of extractions and emissions. An inventory list of all the inputs and outputs of a product or service.
• Impact assessment the effects of the resource use and emissions generated are grouped and quantified into a limited
number of impact categories which may then be weighted for importance.
Interpretation, the results are reported in the most informative way possible and the need and opportunities to reduce the impact of the product(s) or service(s) on the environment are systematically evaluated.
Life cycle impact assessment (LCIA) The inventory list is the result of all input and output environmental flows of a product system. However, a long list of substances is difficult to interpret that’s why a further step is needed known as life cycle impact assessment (LCIA). An LCIA consists of 4 steps:
• Classification: all substances are sorted into classes according to the effect they have on the environment.
• Characterisation: all the substances are multiplied by a factor which reflects their relative contribution to the environmental impact.
Note: Characterisation scores are calculated per effect by multiplying emission with corresponding characterization factors.
Most of the factors used have been developed by the Institute of Environmental Sciences (CML).
• Normalisation: the quantified impact is compared to a certain reference value, for example the average environmental impact of a European citizen in one year.
Note: Normalisation scores are done by multiplying characterization scores with normalization factors. Normalization factors are determined by the effect-scores of economic activities in a certain area during a certain amount of time. Although normalization does not tell anything about the weight or seriousness of environmental effects, it is likely that effects with a relatively high normalization score also are effects that are among the relevant effects for that specific situation.
• Weighting: different value choices are given to impact categories to generate a single score.
For each substance, a schematic cause response pathway needs to be developed that describes the environmental mechanism of the substance emitted. Along this environmental mechanism an impact category indicator result can be chosen either at the midpoint or endpoint level.
• Midpoint impact category, or problem-oriented approach, translates impacts into environmental themes such as climate change, acidification, human toxicity, etc.
• Endpoint impact category, also known as the damage-oriented approach, translates environmental impacts into issues of concern such as human health, natural environment, and natural resources. Endpoint results have a higher level of uncertainty compared to midpoint results but are easier to understand by decision makers.
EPSASA sees the active lifetime of a product as starting with the extraction of raw materials and ending beyond disposal. That is why EPSASA works closely with Plastics SA and is a registered Member. Plastics SA is the mouthpiece of South African plastics industry. Previously known as the Plastics Federation of South Africa, they represent polymer producers and importers, converters, machine suppliers and recyclers.
Interpretation according to ISO 14044 describes a number of checks you need to make to ensure the conclusions are adequately supported by the data and procedures used in the study. The following checks are recommended:
TABLE 6 Life Cycle Assessment (LCA) of Expanded Polystyrene
* lhv = lower heating value
The figures above show the weighted averages of the characterisation and normalization scores for the life cycle of 1kg of EPS material. These are European averages for densities varying from 15-20 kg/m3. Proper comparison with other insulating materials is only possible when the same “functional unit” is used in calculations, e.g. one square meter of insulated area with the same thermal properties.
3.6 ASSESSING EXPANDED POLYSTYRENE
Insulation is generally assessed in two ways, firstly, as a stand-alone element with its own functional unit consisting of 1m² of insulation with sufficient thickness to provide a thermal resistance value of 3 m²K/W, equivalent to approximately 100 mm of insulation with conductivity (k-value) of 0.033 W/m.K. and then also when included as a component within the other relevant building specifications for external walls, roofs and floors of buildings.
In the Green Guide – Environmental Impact of Insulation, all insulations have been compared on the basis of the same 60-year study period, assuming that they all provide continued thermal resistance and do not require any maintenance or replacement during the time. Impacts from installation such as transport, blowing and wastage are included in modelling the functional unit. At the end of the study period, the disposal of all insulations to landfill, incineration or recycling is modelled.
The thermal insulation ratings of EPS is listed below.
TABLE 7 Summary of Green Guide Ratings for Expanded Polystyrene
*Refer table 6 of Green Guide- Environmental Impact of Insulation – Published by BRE Trust 2011
The thermal insulation ratings are the same for all building types (domestic, health, commercial, retail, industrial and education). The Green Guide is part of BREEAM (BRE Environmental Assessment Method) an accredited environmental rating scheme for buildings in the United Kingdom and the Green Guide ratings can be seen at www.bre.co.uk The data is set out as an A+ to E ranking system, where A+ represents the best environmental performance / least environmental impact, and E the worst environmental performance / most environmental impact. BRE has provided a summary environmental rating – The Green Guide rating, which is a measure of overall environmental impacts covering the following issues:
• Mineral resource extraction
• Ecotoxicity to Freshwater
• Nuclear waste (higher level)
• Ecotoxicity to land
• Fossil fuel depletion
• Photochemical ozone creation
4. Compliance with SANS 204 Energy Efficiency in Buildings4.1 OCCUPANCY CLASSIFICATION APPLICABLE TO REGULATION XA3
The highlighted grey areas in the Occupancy or Building Classification in accordance with Regulation A20 in the table below are the applicable occupancy classes relevant to the energy usage regulation XA3 and the red NC indicates the relevant occupancies where only non-combustible insulation materials can be used.
4.2 CLIMATIC ZONES
South Africa has been divided into 6 climatic regions. To achieve the best results, building design and construction materials should be appropriate to the climate of a region. The recommendations for the correct ‘R-Value’ are based on the climatic conditions in particular zones. While each of the six climate zones have different heating and cooling needs, the same principles of energy efficient design apply, with their application varying slightly, e.g. different levels of insulation or thermal mass or variations in window sizes, orientation and shading.
4.3 THERMAL REQUIREMENTS IN ACCORDANCE WITH SANS 204
4.3.1 Floors
4.3.1.1 With the exception of zone 5, buildings with a floor area of less than 500 m², with a concrete slab-on-ground, shall have insulation installed around the vertical edge of its perimeter which shall
a) have an R-Value of not less than 1,0,
b) resist water absorption in order to retain its thermal insulation properties, and
c) be continuous from the adjacent finished ground level
1. to a depth of not less than 300 mm, or
2. for the full depth of the vertical edge of the concrete slab-on-ground.
4.3.1.2 Where an under floor (in-screed, under floor heating, under laminate heating, under carpet heating, under tile heating, cut-in under floor heating or water based under floor heating) heating system is installed, the heater shall be insulated underneath the slab with insulation that has a minimum R-Value of not less than 1,0.
4.3.1.3 With the exception of climatic zone 5, a suspended floor that is part of a building’s envelope shall have insulation that shall retain its thermal properties under moist conditions and be installed
a) for climatic zones 1 and 2, with a partially or completely unenclosed exterior perimeter, and shall achieve a total R-Value
of 1,5,
b) for climatic zones 3, 4 and 6, with a partially or completely unenclosed exterior perimeter, and shall achieve a total
R-Value of 1,0, and
c) with an in-slab in floor heating system, and shall be insulated around the vertical edge of its perimeter and underneath the
slab with insulation having a minimum R-Value of not less than 1,0.
Note: Care should be taken to ensure that any required termite management system is not compromised by slab edge insulation.
In particular the inspection distance should not be reduced or concealed behind the insulation.
4.3.2 Walls
4.3.2.1 Masonry walls: – such as, but not limited to, cavity, grouted cavity, diaphragm, collar-jointed and single leaf masonry, shall achieve the minimum CR-Value given in table 12 for the different types of occupancies in the different climatic zones.
Note: For the CR-Values of walls, contact the relevant manufacturer(s). Table 13 provides typical values for double brick masonry walls, with or without additional insulation.
TABLE 14 Minimum CR-Value, in hours, for external walling
TABLE 15 – Typical CR-Values
4.3.2.2 External non-masonry walls: – shall
a) achieve the CR-Values given in table 15 by the addition of capacity, or resistance (or both),
b) have the following minimum R-Values (except A5, D1 to D4, J1 to J4 which have no minimum R-Value requirements):
1. for climatic zones 1 and 6, a total R-Value of 2,2; and
2. for climatic zones 2, 3, 4 and 5, a total R-Value of 1,9; or
c) have R-Values that comply with the requirements of ASTM C 177, ASTM C 518 and ASTM C 1363.
Note: Internal walls in buildings with this type of external walling may be masonry or non-masonry.
4.3.2.3 Attached buildings such as garages, glasshouses, solariums or pool enclosures to the main building shall
a) have an external fabric that achieves the required level of thermal performance for that building,
b) be separated from the main building with construction having the required level of thermal performance for the building
(see figure 2), or
c) not compromise the thermal performance of the main building.
In addition, an attached building can only be exempted from the regulations if it does not contain habitable spaces and is not provided with a heating/cooling installation, or if any heating/cooling installation is entirely fed from renewable energy sources.
In figure 2 option A, the thermal performance required for the main building may be achieved by the outside walls and floor of the garage and in figure 2 option B, the thermal performance required for the main building may be achieved by the walls and floor of the main building as if the garage were an under-floor space with an enclosed perimeter.
4.3.3 Roofs
A roof assembly shall achieve the minimum total R-Value specified in table 16 for the direction of heat flow.
Thermal insulation shall comply with minimum required R-Values and be installed so that it.
a) abuts or overlaps adjoining insulation, or is sealed,
b) forms a continuous barrier with ceilings, walls, bulkheads or floors that contribute to the thermal barrier, and
c) does not affect the safe or effective operation of any services, installation, equipment or fittings.
Thermal insulation material shall be either.
a) non-combustible when tested in accordance with SANS 10177-5, and may be installed in all occupancy classes; or
b) classified as combustible in accordance with SANS 10177-5, and shall be tested and classified in accordance with SANS 428 for its use and
5. Floors5.1 DESIGN CRITERIA
5.2 PERIMETER INSULATION
A substantial amount of heat is lost through an un-insulated slab, resulting in cold, uncomfortable floors. Even if the foundation wall is insulated vertically under the slab (Figure 3), significant heat is still lost from the slab edge that is closest to the cold outside air.
5.2.1 Where and how to install perimeter insulation
The insulation can be applied outside (Figure 4) or inside (Figure 5) the foundation wall to a depth of not less than 300 mm. Exterior applications require a metal flashing or durable finish for protection. The insulation can also be placed vertically along the foundation wall (Figure 5) or horizontally under the slab (Figure 6). Perimeter slab insulation can give termites access, so be sure to provide a termite shield (Figure 7). Some jurisdictions do not allow external insulation because the foundation must be visible for termite inspection.
5.2.2 Perimeter slab insulation protection against moisture and termites
One option is to install the insulation inside the foundation wall and provide a protective membrane (termite shield) between the sill plate and foundation(Figure 6).
5.3 UNDER FLOOR/SLAB INSULATION
EPS floor boards for concrete ground floors comprise of HD and EHD Grades of Expanded Polystyrene. EPS Boards with flame retardant additive are always to be used.
5.3.2 Site Handling and storage
The EPS boards must be protected from prolonged exposure to sunlight and should be stored either under cover or protected with opaque polythene. Care must be taken to avoid contact with solvents and with materials containing volatile organic components such as coal tar, pitch, timber newly treated with Creosote, etc. The EPS boards must be stored flat, protected from high winds and raised above damp surfaces. The EPS boards must not be
exposed to open flame or other ignition sources.
5.3.3 Design Data
EPS floor boards for concrete ground floors are effective in reducing the U-Value (thermal transmittance) of new or existing floors incorporating either a cement based screed or a chipboard overlay.Ground supported floors incorporating the EPS boards must include a suitable damp-proof membrane laid in accordance with SANS 10021. The waterproofing of buildings (including damp-proofing and vapour barrier installation).
The overlay to the EPS boards should be:
1. a cement-based floor screed laid in accordance with the relevant clauses of SANS 10109 Part 2, or
2. chipboard in accordance with SANS 50312 Particleboards – Specifications, or
3. a concrete slab in compliance with SANS 1879 Precast concrete suspended slabs
5.3.4 Properties In Relation To Fire
The EPS boards do not prejudice the fire resistance properties of the floor. When properly installed the EPS boards will not add to any existing fire hazard. The EPS boards will be contained within the floor by the overlay until the overlay itself is destroyed. The EPS boards therefore will not contribute to the development stages of a fire or present a smoke or toxic hazard. Electrical cables running within the EPS boards should be separated from it by enclosing them within a suitable conduit, e.g. rigid PVC.
5.3.5 Moisture Penetration
5.3.6 Thermal Insulation
For the purpose of U-Value calculations to determine if the requirements of the Building (or other statutory) Regulations are met, the thermal conductivity (k-value) may be taken as 0.035 W/(m.K) for HD and 0.032 W/(m.K) for EHD EPS boards. The requirements for limiting heat loss through the building fabric can be satisfied if U Values of the building elements, including the effect of thermal bridging do not exceed the maximum values in the relevant calculation method.
5.3.7 Floor Loading
The design loadings for floors should be:
The EPS boards covered with chipboard or screed can support these design loadings without undue deflection. Where the EPS boards are used under a concrete slab, resistance to concentrated and distributed loads is a function of the slab specification.
5.3.9 Installation
Typical methods of installation for EPS floor insulation for concrete ground floors are shown in Figure 6. The concrete floor over which the EPS boards are to be laid should be left as long as possible to maximize drying out of moisture. The floor surface should be smooth and flat to within 5 mm when measured with a 3 metre straight edge, e.g. when concrete is laid on site it should be in accordance with SANS 10109-1 Concrete floors Part
1: Bases to concrete floors.
Irregularities (up to 10 mm) may be levelled with mortar.
The EPS boards can also be used on a beam and block suspended concrete floor. The surface of the floor should be smooth and flat to within 5 mm when measured with a 3 metre straight edge. Irregularities greater than this must be removed. Where the EPS boards are used over ground-supported concrete floor slabs they should incorporate a suitable damp-proof membrane, in accordance with SANS 10021, to resist moisture from the ground. If a liquid type damp-proof membrane is applied to the slabs, it should be of a type compatible with expanded polystyrene and be allowed to dry out fully before laying the EPS boards.
Where the EPS boards are used on hard-core bases underground-supported concrete slabs, the hard-core must be blinded before application of the EPS boards. Where a screed or concrete slab is laid over the EPS boards, vertical up stands of insulation should be provided and be of sufficient depth to fully separate the screed or slab from the wall. During construction, the EPS boards and overlays must be protected from damage by moisture from sources such as water spillage, plaster droppings and traffic. Before laying EPS boards above a slab, care should be taken to ensure sufficient time
for the dissipation of constructional moisture.
Exposed or semi-exposed intermediate timber floors
Before installing the EPS boards, the floor should be inspected thoroughly for possible defects and its condition should
meet the recommendations of SANS 10109 Part 2. The surface of the floor should be smooth and flat to within 5 mm when
measured with a 3 metre straight-edge.
5.3.10 Installation Procedure
The EPS boards are cut to size, as necessary, and laid with closely butted, taped joints. Cement-based screed overlay Perimeter edge pieces are cut and placed around the edges. A properly compacted screed of at least 65 mm is laid. The relevant clauses of SANS 10109 Part 2 will apply.
Chipboard overlay
Before laying the EPS boards, preservative treated battens are positioned at doorways and to support partitions. Adequate time should be allowed for CCA based preservatives to become fixed, and for the solvents from solvent-based preservatives to evaporate. Where EPS boards are laid on a dpm, a vapour check consisting of 0.25 mm (250 micron) polyethylene sheet is laid between the EPS boards and the chipboard. The polyethylene sheet has 150 mm overlaps taped at the joints and is turned up 100 mm at the walls.
The selection of chipboard/particle board must be in accordance with SANS 50312. An expansion gap between the chipboard and the perimeter walls should be provided at the rate of 2 mm per metre run or a minimum of 10 mm, whichever is the greater.
Where there are long, uninterrupted lengths of floor, e.g. corridors, proprietary expansion joints should be installed at intervals on the basis of a 2 mm gap per metre run of chipboard. Before the chipboard panels are interlocked, either a PVA or mastic adhesive is applied to the joint.
Once the chipboard is laid, temporary wedges are inserted between the walls and the floor to maintain tight joints until the adhesive has set. To prevent cold-bridging suitable compressible filler, e.g. pieces of expanded polystyrene, should be fitted around the perimeter of the floor between the chipboard and the walls when the wedges are removed and before the skirting boards are affixed. Where there is a likelihood of regular water spillage, e.g. in rooms such as kitchens, bathrooms, shower and utility rooms, additional chipboard protection should be considered, for example a continuous flexible vinyl sheet flooring with welded joints and cove skirtings.
Cement-based screed overlay
5.3.11 Inclusion of Services
The maximum continuous working temperature of the EPS boards is 80ºC. The EPS boards must not be used in direct contact with electrical heating cables or hot water pipes.
5.3.12 Suspended beams and blocks floors
5.3.13 Other types of floors
Where possible, electrical conduits, gas and water pipes or other services should be contained within ducts or channels withinthe concrete slab. Where this is not possible, the services may be accommodated within the insulation, provided they are securely fixed to the concrete slab. Electrical cables should be enclosed in suitable conduit. With hot pipes the insulation must be cut back to maintain an air space. Where water pipes are installed, either within the slab or the EPS boards, they must be pre-lagged. For floors incorporating chipboard overlays, where access to the services is desirable, a duct may be formed by mechanically fixing to the floor, timber bearers of the same thickness as the insulation to provide support for a chipboard cover. The duct should be as narrow as possible and not exceed the maximum chipboard spans recommended.
5.3.14 Timber intermediate floors
5.4 SUSPENDED FLOOR
The Total R-Value required is achieved by adding the R-Value of the basic floor and the R-Value of any additional insulation
that is incorporated.
6. Walls6.1 DESIGN CRITERIA
6.1.1 Introduction to CR-Value
The thermal capacity of a material is known as the “C-Value” and it reflects the ability to store heat during the day and to radiate the heat during the night, this process is also known as thermal lagging, and masonry products such as bricks, will typically have a high C-Value, illustrating its ability to provide consistent internal temperatures. The R-Value of a material is the thermal resistance which refers to the ability to resist conducting heat through the material. The higher the CR-Value, the greater the ability of the composite system, i.e. brick wall, to moderate the internal temperature of a building and to minimise the effects of external climatic conditions on the interior of a building.
1. R-Value = 0.5 and R-Value = 1.0 refers to the thermal resistance of the insulation only, expressed in m²K/W. Thermal resistance that is added to external walling with high thermal capacity, should be placed in between layers, for example in the cavity of a masonry wall. Thermal resistance should not be added to the internal face of a wall with high thermal capacity.
2. Wall systems that have low thermal capacity or resistance (or both) will not meet the minimum CR-Values, in hours, for external walling in accordance with SANS 204 Table 3.
3. Designers should consider that interstitial condensation occurs in walling systems which are not able to prevent or accommodate moisture migration. The selection of vapour barriers and appropriate construction materials, including insulation, is important for the thermal efficiency of walling in climate zones where damp and high relative humidity is experienced.
4. Internal walls in buildings with external walling should ideally have CR-Values of at least 20 h but this is not a requirement for compliance.
6.2 EPS CAVITY WALL INSULATIONS
Expanded Polystyrene (EPS) insulation, when installed in accordance with this Guide, is effective in reducing the thermal transmittance (U-Value) of the walls of new and existing buildings. Recommended density for wall insulation is both standard or high density. High density is recommended for cold humid areas. EPS cavity wall insulation is made from standard EPS boards in thicknesses and edge profiles to suit the applications. EPS boards are for use as a complete or partial fill to reduce the thermal transmittance of cavity walls with masonry inner and outer leaves. The installation of EPS insulation during the construction of walls must be carried out by competent contractors.
6.2.2 Site Handling and storage
EPS boards are delivered to site in protective plastic packaging and should be stored under cover. The EPS boards shouldbe stored on a firm, clean, level base, off the ground and under cover until required for use. Care must be taken when handling the insulation to avoid damage. The EPS boards must be protected from prolonged exposure to sunlight, either by storing opened packs under cover or recovering with opaque polyethylene sheeting. Care must be taken to avoid contact with solvents or materials containing volatile organic components such as coal tar, pitch, timber newly treated with creosote, etc. The EPS boards must not be exposed to open flame or other heat sources and should not be stored near flammable liquids.
6.2.3 Design Data
EPS boards are not to be considered as contributing to the structural strength of the walls. The width of the EPS boards and any additional gaps are considered as the cavity for structural purposes. Cavity walls must comply with the rules of the National Building Regulations or be designed in accordance with SANS 10164-1 by a competent person. Adequate wall tie densities must be achieved in both vertical and horizontal planes.
6.2.4 Properties In Relation To Fire
In the opinion of EPSASA it is highly unlikely that the EPS board will ignite in the cavity. The use of the EPS boards will not introduce any additional hazard in respect of behaviour in fire when compared with traditional walls. However, in terms of SANS 10177-5, EPS boards on their own are considered combustible. Cavities are to be bricked closed horizontally and/or vertically around the perimeters of defined fire rated compartments, and around any openings e.g. windows, doors, to prevent movement of toxic fumes or hot gases. EPS boards must not be stored near flammable liquids, waste etc. and not exposed to heat or open flames.
6.2.5 Moisture Penetration
6.2.6 Thermal Insulation
For the purpose of U-Value calculations to determine if the requirements of building regulations or other regulations are met, the thermal conductivity (k-value) of the insulation may be taken as 0.037 W/(m.k.) This value allows for an increase in thermal conductivity due to ageing and water absorption. Where the insulation has not been continued into window or door reveals due to a lack of clearance, there will be a risk of cold bridging at these points. Where door and window frames are to be replaced, it is recommended that their size be adjusted to permit the reveals to be insulated. Depending on constructional details, cold bridging can also occur at the eaves and at ground-floor level, and care should be taken to minimize this, e.g. roof or loft insulation should continue over the wall head, ensuring that ventilation openings are not obstructed.
6.2.7 Durability
EPS boards for cavity walls are effective as insulation for the life of the building. EPS boards are rot-proof, offer no food value and will remain durable and stable. EPS boards must be stored in terms of 7.2.2.
6.2.8 Technical Specification
a) The walls are constructed leading with either the inner or outer tier. If a residual cavity is specified the inner tier must thenbe constructed ahead of the outer tier and the insulation fixed to the cavity face of the inner tier. Fixing EPS boards in this manner enhances the thermal performance.
b) EPS boards are fixed to the cavity face of the leading tier with wire ties which are additional to the cavity ties specified. These additional ties may be standard cavity ties or may be made from 2 mm diameter L-shaped galvanized wire. They must be installed at the same height and mid-way between the specified cavity ties. The EPS boards must be held firmly in place while these additional ties are bent in position. Ties are bent up and down alternately to secure the lower and upper edges of the EPS boards.
• After a few rows of EPS boards have been positioned the building of the second tier progresses insuring that if a residual cavity is required the cavity ties and cavity itself remain clear of mortar droppings.
d) The thickness of the wall tiers and the cavity widths define the horizontal spacing of the cavity ties. Ties are installed at vertical spacings of 600 mm and coincide with the horizontal joints of the EPS boards. Where window and door openings are provided, and at control joints the vertical spacing of the cavity ties must be reduced to 300 mm. EPS boards must be cut to accommodate these ties. During installation of the EPS boards care must be taken not to loosen the cavity ties
embedded in mortar joints.
e) The use of cavity boards and battens helps to keep cavities and the exposed top edges of the EPS boards free of mortar droppings.
f) EPS boards may be cut using a sharp knife or a fine tooth saw to fit round window or door openings. No gaps must be left in the insulation. Cut pieces of EPS boards must be glued in position to completely fill open spaces.
6.2.9 Installation
7.2.9.1 Brick or block gauges must be set so that cavity ties coincide with the width of the EPS boards at the horizontal joints of the wall insulation.
7.2.9.2 The embedded depth of the cavity ties must be at least 50 mm in the mortar joints of each leaf. Crimped wire ties and single wire type Z-ties with central dished drips cannot be used. Cavity ties must meet the requirements of SANS 28 Metal ties for cavity walls. Suitable wall tie types for cavity widths less than 75 mm are:
• Vertical Twist
• Modified PWD
For cavities greater than 75 mm in width, only vertical twist ties (with a stiffness equal to hoop iron – mild steel 20 mm wide and 4 mm thick) must be used.
6.2.9.3 The wall ties spacing for various cavity widths must be:
Horizontal spacing of ties with vertical spacing of 600 mm to comply with the tie density as required in table 7 of SANS 10164 (nominal thickness of each leaf 90 mm or more).
6.2.9.4 If EPS boards with shiplap joints are used, the shiplap joints must be arranged to disperse water from the inner leaf (see fig 16).
6.2.9.5 Debris and mortar must be removed from the cavity and exposed edges of installed EPS boards as work progresses.
6.2.9.6 EPS boards must be interlocked tightly with no gaps at the top and bottom of the wall, at the corners and around windows and other openings.
EPS CAVITY INSULATION
6.3 NON-MASONRY WALLS WITH EPS INSULATION
6.3.1 Design criteria
6.3.2. General
Expanded Polystyrene (EPS) insulation, when installed in accordance with this Guide, is effective in reducing the thermal transmittance (U-Value) of the non-masonry such as light steel frame buildings or timber frame buildings. EPS cavity wall insulation is made from standard EPS boards in thicknesses and edge profiles to suit the applications. EPS boards are for use as a complete fill to reduce the thermal transmittance of cavity walls in non-masonry external walls. The installation of EPS insulation during the construction of walls must be carried out by competent contractors.
6.3.3 Site Handling and storage
EPS boards are delivered to site in protective plastic packaging and should be stored under cover. The EPS boards should be stored on a firm, clean, level base, off the ground and under cover until required for use. Care must be taken when handling the insulation to avoid damage. The EPS boards must be protected from prolonged exposure to sunlight, either by storing opened packs under cover or recovering with opaque polyethylene sheeting. Care must be taken to avoid contact with solvents or materials containing volatile organic components such as coal tar, pitch, timber newly treated with creosote, etc. The EPS boards must not be exposed to open flame or other heat sources and should not be stored near flammable liquids.
6.3.4 Design Data
EPS boards are not to be considered as contributing to the structural strength of the walls. Cavity walls must comply with the rules of the National Building Regulations or be designed in accordance with SANS 10400 Part K by a competent person.
6.3.5 Properties In Relation To Fire
In terms of SANS 10177-5, EPS boards on their own are considered combustible. EPS boards used in the cavity of nonmasonry walls shall however be tested as a complete system in accordance with SANS 10177-2 Fire testing of materials, components and elements used in buildings Part 2: Fire resistance test for building elements. EPS boards must not be stored near flammable liquids, waste etc. and not exposed to heat or open flames.
6.3.6 Moisture Penetration
A vapour permeable waterproofing membrane must be attached to the outside of the steel structure and cover the entire surface of external walls, excluding doors, windows and other penetrations. Damp proof courses must be provided underneath bottom wall plates of all exterior walls.
6.3.7 Thermal Insulation
For the purpose of U Value calculations to determine if the requirements of building regulations or other regulations are met, the thermal conductivity (k-value) of the insulation may be taken as 0.037 W/(m.k.) This value allows for an increase in thermal conductivity due to ageing and water absorption. Where the insulation has not been continued into window or door reveals due to a lack of clearance, there will be a risk of cold bridging at these points. Where door and window frames are to be replaced, it is recommended that their size be adjusted to permit the reveals to be insulated.
Depending on constructional details, cold bridging can also occur at the eaves and at ground-floor level, and care should be taken to minimize this, e.g. roof or loft insulation should continue over the wall head, ensuring that ventilation openings are not obstructed.
7.3.8 Durability
EPS boards for cavity walls are effective as insulation for the life of the building. EPS boards are rot-proof, offer no food value and will remain durable and stable. EPS boards must be stored in terms of 8.3.3.
7.3.9 Installation
7.3.9.1 Insulation must be installed so that it abuts or overlaps adjoining insulation, meets window or door frames or elements of the steel structure without a gap, and forms a continuous barrier with the insulation of the roof, ceiling, floors or other parts of the building envelope.
7.3.9.2. EPS insulation boards must be installed so that it maintains its position and thickness, except where it has to be compressed to accommodate services.
7.3.9.3 The sealing and flashings around doors, windows and other penetrations through walls shall be such as to prevent uncontrolled air flow through the joints, and to cause any moisture to drain to the outside of the building, for which weep holes must be provided. Refer to Figure 17.
7.3.9.4 The joints between the internal cladding and the ceiling or floor must be sealed using elastic sealant, caulking, cornices and / or skirting to minimize air leakage through these joints, to enhance the thermal and acoustic insulation properties of the wall assembly.
7.3.9.5 If the external cladding consists of weatherboard, fibre cement sheeting or metal sheeting a thermal break with an R-Value of at least 0,2 must be installed between the steel frame and the cladding. Expanded polystyrene of not less than 12 mm or timber of not less than 19 mm thickness may be deemed to have an R-Value of at least 0,2.
7. Roofs7.1. Roofs
The type and design of thermal insulation in new buildings depend on the construction and subsequent use of the building. Different levels of thermal insulation for the shell of the building are required based on the purpose of the building and must be fulfilled. The thermal properties include the effects of thermal bridging.
8.2 ROOF STRUCTURES
Pitched or flat roofs can be built in various designs, irrespective of the shape of the roof. A distinction is made between light and heavy styles. Pitched roofs are usually built in light wooden structures and flat roofs in heavy concrete or light metal designs.
8.2.1 Pitched roof
Pitched roofs can generally be fitted with over-rafter or between-rafter insulation, or a combination, as under-rafter insulation.
Pitched tile roof with flat ceiling
Pitched metal roof with flat ceiling
8.2.2 Flat roof
In conventional flat roofs, insulation is added over the supporting roof construction. The insulating material must be able to permanently withstand the load of the sealing, gravel layers or terracing or green roof system.
Flat roof and cathedral ceiling – ceiling lining under rafters
Flat roof and cathedral ceiling – ceiling lining on top of rafters (exposed rafters)
8.2.3 Site Handling and storage
8.2.4 Design Data
EPS boards are not to be considered as contributing to the structural strength of the roof. Roofs must comply with the rules of the National Building Regulations and be designed in accordance with SANS 10400 Part L – Roofs and Part T – Fire protection.
8.2.5 Properties In Relation To Fire
In terms of SANS 10177-5 Fire testing of materials, components and elements used in buildings Part 5; Non-combustibility at 750 °C of building materials, EPS boards on their own are considered combustible. This does not mean that the product cannot be used. It is a requirement for all manufacturers of EPS boards or composite boards (laminated with facings) to test their individual products in accordance with the type of installation system as it would be in practice, i.e. over purlin, under
purlin or suspended ceiling application, in accordance with SANS 428 Fire performance classification of thermal insulated building envelope systems.
EPS boards must not be stored near flammable liquids, waste etc. and not exposed to heat or open flames.
8.2.6 Thermal Insulation
For the purpose of thermal calculations to determine if the requirements of the building regulations are met, the thermal conductivity (k-value) of the boards may be taken as:
• SD – 0.038 W/(m.K)
• HD – 0.035 W/(m.K)
• EHD – 0.032 W/(m.K)
8.2.7 Durability
8.28 Installation
The installation must be strictly in accordance with the Manufacturers installation specifications.