All information on this page is copied material from Gulvfakta, which is a technical reference material, Source: Gulvfakta

3.1 Introduction
For a floor to function satisfactorily, it must have a number of properties which depend on the intended use, i.e. the floor must have properties so that it can:
• Fulfill the functions it must have, e.g. to form a floor surface, to provide walking safety, to be heat-resistant, to be waterproof and to be wear-resistant
• Cope with the influences it is expected to be exposed to, eg static and dynamic forces, temperature fluctuations, chemical influences and wear.
The functions of the floor and the expected impacts during use must be clarified during the design.

The properties the floor must have will be the same for most applications. They must, for example, be able to withstand mechanical loads and chemicals. The requirements, on the other hand, depend on the current use, e.g. how heavy loads are expected or which chemicals the floor must be able to withstand. The most important properties and their importance are briefly discussed below in qualitative form. There is therefore no reference to test methods or assessment criteria. These are given in the description of the respective materials. Depending on the type of coating, the test methods used to document the properties may be different.

Flatness
The floor must be so level and horizontal that people can occupy it and furnish it without hindrance. In certain cases, there are stricter requirements for flatness, for example in high-rise warehouses and TV studios.
During renovation tasks or when laying a floor on concrete elements with pile height, the substrate may have large deviations from the horizontal. In such situations, it should be considered whether a slight slope on the floor is acceptable, as it may entail large additional costs to make an alignment to the horizontal. Strict requirements for flatness will usually make the floor laying work more difficult and thus more expensive.
Strength and stiffness
The floor (floor covering) must be able to withstand the static and dynamic loads, e.g. from payloads, furniture, people and rolling traffic, which must normally be expected to occur during the intended use. In the intended use, the floor must not be deformed to such an extent that it disturbs the use.
Robustness
The floor (floor covering) must be so robust that it can withstand minor mechanical impacts during use, e.g. from furniture legs or falling objects, without breaking or causing permanent marks on the surface.
Walking safety
The floor (floor covering) must not present a danger of people slipping or tripping during normal activities. The most frequently used floor coverings usually have an acceptable slip resistance if they are clean, dry and free of oil, grease and other slippery substances. The walking safety of a floor therefore depends not least on the daily cleaning and maintenance of the floor. If wet floors are expected, and especially where water is combined with waste from production, as is often seen in the food industry, special measures must be taken to avoid falling accidents, as such floors can become very slippery.
Walking comfort
The floor (floor covering) must be so springy and/or soft that no unpleasant hardness is felt during normal use. Fire engineering properties

The floor (floor covering) must have such fire-resistant properties that, in the event of a fire, it does not increase the risk of personal injury by:
• Not protecting underlying material from ignition
• Even contributing to the spread of fire
• To develop heavy smoke or toxic gases.

Abrasion resistance
The floor (floor covering) must be so durable that other properties, e.g. flatness, ease of cleaning and appearance, are maintained to a satisfactory extent during the intended period of use.
For floor coverings that require surface treatment, the wear resistance with/from the surface treatment should be assessed. The price of the treatment should be included in the decision-making process. The price must reflect the scope of work and the time interval between treatments.
Heat resistance
The floor (floor covering) must not change its other properties or take permanent damage from deformations caused by heat. Floor coverings etc. to be used in connection with underfloor heating systems must be able to withstand the temperatures that can be expected to occur in the current construction.
Stability against moisture
The floor (floor covering) must not suffer harmful deformations due to moisture effects from normal use.
Resistance to chemical influences
The floor (floor covering) must be able to withstand the effects of chemicals, including cleaning agents, which are expected in the intended use. The assessment must take into account whether it is a short-term impact, e.g. from stain removers, or a long-term impact, e.g. normal waste in an industrial production. If exposure to special chemicals is expected, their impact on the floor material should be investigated.
Electrostatic properties
The floor (floor covering) must not be responsible for such large electrostatic charges from people walking on it that it can give rise to annoying electrical discharges.
In addition to being a nuisance to people, electrical discharges can cause problems in connection with electronic equipment or explosive materials.
Thermal comfort
The floor (floor covering) must feel warm and pleasant to step on. This can either be achieved by using floor coverings that are in themselves thermally comfortable, or by using underfloor heating systems. The property is particularly important where longer stays are expected or where children play on the floor.
Acoustic properties
The floor (floor covering) must be able to help prevent the sound of footsteps or wind noise from contributing to the noise level in the same or adjacent rooms in a disturbing way. It should be noted that, in addition to the influence of the floor materials, there is a large influence from the execution, for example whether there are "sound bridges" in a floating floor construction.
Water tightness
Floors (the floor covering) in wet rooms, including joints and pipe passages, must be waterproof.
Cigarette glow
In certain cases, the floor (floor covering) must be able to withstand short-term exposure to cigarette embers without permanent burn marks or other damage.
Flexibility
Floor coverings of track goods, when they are used in pits etc., must be so flexible that they are not damaged due to bending.
Life
The floor (floor covering) must be able to maintain its properties to a satisfactory extent over a long period of time exposed to normal degradation factors, e.g. UV light, moisture or physical stresses from use.

3.2 Building moisture
Concrete is a porous material and contains water even though it appears dry.
When laying cement-based products, water and cement are mixed into a mushy mass. The cement begins to harden immediately after being mixed with water and gradually forms a solid structure. The water is bound to the cement chemically and physically, respectively. The mixing ratio between water and cement is called the "water-cement ratio". At a mixing ratio of 0.4 (ie 2 parts water to 5 parts cement) all the water will be bound to the cement, 25% will be bound chemically and 15% will be bound physically. The cement is said to be self-drying. If there is more water in the mixture, it will still be found in the cement's pore system (as steam), it is this water that determines the cement's moisture content. The "free" water will evaporate from the concrete, as long as the humidity in the concrete is higher than the humidity in the surrounding air. Below are a number of examples of equilibrium curves for different materials.

In Denmark, we often indicate the moisture content of the concrete in %RH. What we are actually reporting is the moisture content of air that is in equilibrium with the concrete.

Building moisture
Construction moisture (residual construction moisture) is the moisture that is not consumed in the concrete's hardening process and must therefore be removed. Before laying the floor, it is necessary that construction moisture in the substrate has dried out to a moisture level that is acceptable for the current floor covering.

Drying out construction moisture can be a very time-consuming process, which can take several months in the worst case. There is therefore good reason to carry out the subfloor so that it only contains modest amounts of construction moisture. There are two possibilities for this. Either you can choose substrate types that do not contain building moisture, for example sheet materials that are protected by a moisture barrier if necessary. Otherwise, material compositions can be used in which no more moisture is added than is needed.

It is not always possible to completely avoid construction moisture, but it will often be possible to choose material compositions so that the amount of construction moisture is significantly limited, e.g. self-drying concrete, i.e. a concrete composition with a low water-cement ratio.

In the Concrete Book (published by CtO), a calculation model for the drying time of concrete floors is specified (table 3.4 -4 on page 197)

Table 2. Schedule from CtO. (Drying times for concrete floors).

The calculation model is based on traditional Danish concrete types and execution methods and takes into account, among other things, water-cement ratio, thickness and drying conditions. By using the model on the actual concrete floor, the time for laying the floor can be calculated based on estimates. As the calculations are only indicative, the moisture content must always be checked by measurement before the floor installation begins.

For screeds, information on building moisture and drying times must be obtained from the supplier.

Moisture requirements for the construction site when laying the floor
All work that can add moisture to the building, e.g. brickwork and basic painting including plastering must be completed. The building must be in equilibrium with a normal humidity for the season at approximately 20°C. For concrete or lightweight concrete decks, it will require a few months of drying out. If necessary, drying must take place by moderate use of dehumidifiers. Wooden floors place particularly high demands on the moisture-technical conditions on the construction site.

The dimensions of wood depend on the moisture content of the wood, which in turn depends on the relative humidity (RH) and temperature of the surroundings. Examination of moisture conditions in connection with the laying of floors on concrete cannot normally be done by measuring relative humidity, but must be done in the substrate. The reason is that air conditioning or strong ventilation can lower the relative humidity of the air without a sufficient lowering of the moisture in the concrete.

If floors are to be laid in conditions where it is necessary to protect against building moisture from the underlying concrete, moisture build-up can be prevented by using a suitable moisture barrier, e.g. cast asphalt or epoxy with documented functionality. For floating wooden floors and wooden floors on joists, 0.20 mm PE foil can be used.

Checklist for flooring:
• The relative humidity in the building must be between 35 and 75% (for wooden floors between 30 and 65%), depending on the season, and the temperature approx. 20°C. These conditions should be observed before, during and after the floor is laid.
• The building must be closed, and during the heating season the heating system must be installed and in use
• The maximum moisture content in concrete, lightweight concrete, etc. on which floor coverings must be glued appears under requirements for the place of execution for the individual floor covering types

Construction of floor structures
Problems with moisture in floors can either be due to incorrect construction of moisture-sensitive constructions, e.g. terrain decks and crawlspaces, or insufficient drying of building moisture before applying moisture-sensitive materials.

To ensure a moisture-technically correct construction, floor constructions should be carried out in accordance with the guidelines given in SBI instruction 224: Moisture in buildings.

3.3 Moisture measurement in concrete decks
For many floor coverings, it is a prerequisite for problem-free use that there is no severe or long-lasting influence of moisture from below during construction and use. Exposure to moisture can partly lead to dimensional changes and deformations of the floor covering, partly to breakdown of glue and putty. Before laying the floor, it must therefore always be ensured that there is not too much moisture in the substrate.

For new tires this must be ensured by measuring the moisture content in the tire before the floor laying work begins. For this type of deck, there is a real risk of an excessively high moisture content arising from the construction process (residual construction moisture), see also the section on construction moisture. On old well-dried decks, where only the floor covering needs to be replaced, moisture in the deck will rarely be a problem.

In older all-terrain decks, basement decks and the like, there may be rising ground moisture due to a lack of moisture barriers in the construction. Moisture measurement should therefore also be carried out in such constructions if diffusion-proof floor coverings are to be laid. If a moisture content of over 65% RH is found in older concrete decks, the structure should be examined more closely before the floor is laid.

The building regulations
The building regulations prescribe that buildings must be constructed so that water and moisture do not cause damage or inconvenience, including reduced durability and unsatisfactory health conditions. This means that when tendering, planning, projecting and carrying out building constructions, the measures that are necessary for proper execution due to climatic conditions must be taken.

This provision must, among other things, ensure that no materials with mold are built in during the construction period, and in the regulation's guidance text it can be read that the functional requirement is ensured, among other things, by an appropriate quality assurance procedure, and that the responsibility for the necessary drying lies with the client (or his advisers) as the client in the tender and timetable must explicitly set aside time for the necessary drying of building materials and building structures.

Subsequently, it is equally important to check that the acceptable moisture level has been reached. For laying all types of floor coverings, it is crucial that the residual moisture content in the concrete subfloor is measured with an accurate moisture measurement.
If floor coverings are to be laid directly on a concrete deck, the following general requirements apply to RF in the substrate.

Table 1. Maximum permissible relative humidity percentage in concrete as a substrate for floor coverings. For wooden floors, please also refer to the section on choosing glue. ATTENTION! Concrete deck with underfloor heating

Gulvfakta's guidance on moisture measurement and maximum moisture percentages cannot be used in concrete decks with underfloor heating. It is therefore recommended that the client engages a consultancy firm with knowledge of moisture measurement before the floor is laid.

In the following, a description is first given of how concrete decks dry out, followed by a description of the moisture control that should be carried out by the client and contractor respectively.

Moisture content in concrete
The moisture distribution in a concrete slab is in practice three-dimensional. The moisture will vary over the surface and over the cross section. The moisture distribution over a floor surface can vary considerably, depending on the casting time, difference in concrete composition, sunlight, draft etc. The moisture distribution can be determined relatively easily with a surface scanner, but be aware that the values measured with a surface scanner are not accurate. The readings will, in addition to the moisture content, depend on the composition (quality) of the concrete and measurements with a surface scanner can thus only be used to determine the moistest and the driest areas - the moisture distribution over the floor surface.

Concrete slabs dry out from the outside towards the centre. A concrete slab with two-sided drying (ie with drying from both the top and bottom) will consequently have the highest humidity in the center of the slab, see figure 6a.

When a more or less dense floor covering is laid out on a concrete slab that has not fully dried, there will be a redistribution and equalization of the moisture in the concrete slab. The principle for this is shown in Figure 6a (for two-sided drying). The exact shape of curve C will depend on how closely a coating is fitted to the concrete slab.

Figure 6a: Moisture profile with two-sided drying. a=moisture profile before drying, b=moisture profile after and during drying, c=moisture profile installation of floor covering, H=thickness of the concrete slab.

The "equivalent depth" is found in the intersection between the curves b and c. At this depth, you have the same moisture % before and after installing the floor covering. The "worst imaginable situation" is achieved with a completely diffusion-tight floor covering. In this situation, the equivalent depth = 0.2 x the thickness of the concrete slab (with two-sided drying).

For a concrete slab with one-sided drying out (basement floors and floors on terrain decks), the drying out profiles will look like shown in Figure 6b. The equivalent depth will here be 0.4 times the thickness of the concrete slab.

Figure 6b: Moisture profile with one-sided drying. a=moisture profile before drying, b=moisture profile after and during drying, c=moisture profile installation of floor covering, H=thickness of the concrete slab.

With reference to the above, it is important to measure at the right depth if you want to assess whether a "raw" concrete floor (with one-sided drying) is ready for flooring in terms of moisture. If you measure "too deep" (>0.4xH) too high values are obtained - the floor is not as moist as it is measured - if you measure "too high" (< 0.4xH) you get too low values - the floor is more moist than it seem. The same applies to tires with two-sided drying. It is rare that, in connection with construction, there are problems with the drying out of deck decks (decks with two-sided drying). If there are problems, it is often on the one-sided dried out tires, such as off-road and basement tires. In practice, there are many uncertainties associated with moisture measurements in concrete decks. The flooring industry therefore recommends that you always measure at a depth corresponding to 0.5 x the tire thickness for all-terrain tires and other tires with one-sided drying and at a depth corresponding to 0.25 x the tire thickness for tires with two-sided drying.

In what follows, scope, responsibility and methods are described. As previously mentioned, it is the responsibility of the builder to ensure proper drying of the building and, via quality assurance, to document this. The builder's quality assurance should document the ongoing drying of the concrete surfaces (and the building in general) until the time when the floor laying work begins. While the floor contractor's moisture measurement should only be considered as a confirmation of the builder's measurements. A receiving inspection carried out on a random sample basis.

The builder's moisture control includes:
• A non-destructive mapping of the distribution of moisture over the floor surface
• A number of (destructive) measurements of the moisture in the tire.
The developer must also ensure that channels in element decks are emptied of water when the building is closed.

The contractor's moisture control includes:
• A non-destructive mapping of the distribution of moisture over the floor surface
• A destructive measurement in the most humid area.
The procedure is the same for both the client and the flooring contractor, but since the responsibility for drying out lies with the client, the flooring contractor generally only includes a destructive measurement. A measurement that simply verifies the builder's measurements. It is recommended that the check be carried out approx. 14 days before the floor work begins.

Procedure - mapping the distribution of moisture
When mapping the moisture distribution, it is recommended that the floor be divided with a modular grid. The modular grid from the drawing material can be used as a starting point, as element assemblies, columns, window placements and the like follow this system. The grid is chosen so that within each mesh in the module grid there are approx. 5 - 10 m2. A non-destructive measuring device is used, for example a capacitive moisture meter, which is suitable for recording moisture differences. It is measured at the intersection points in the network. The display of the instrument is noted on the drawing. Based on the recorded values, the wettest and the driest areas can be located. On the basis of the registration, the points are selected where the actual moisture measurement (destructive measurement) is to take place. The measurements can usually be limited to an examination of the moisture content in the most humid areas, as it is these that determine whether flooring can be laid or not. The moisture content is determined as the equilibrium moisture content of the concrete, measured in % relative humidity (RH).
Destructive measurements
You can choose between performing the measurement on site in a "measuring hole" (often called a borehole measurement) or measuring on a material sample that has been brought to the laboratory. The two methods are subsequently described.
Borehole measurements
With this method, the moisture content of the concrete is measured on site. The measurement is carried out in drilled holes or embedded liners in the floor, see figure 6c.

Figure 6c. Moisture measurement in concrete by measuring relative humidity in boreholes.

For concrete decks with one-sided drying, off-road decks etc. drill a hole of approx. 0.5 x the concrete thickness. The borehole is thoroughly cleaned of dust, the sides of the borehole are insulated for moisture penetration to a depth of approx. 0.4 x the thickness of the concrete slab and plugged. It is important that the plugging is airtight and that the hole can be kept closed until equilibrium has been achieved between the moisture in the concrete and the air in the hole. According to experience, this takes 4-5 days.

The relative humidity in the borehole can now be measured with a calibrated moisture meter. The temperature must be between 15 and 25 °C when measuring, and any floor heating system must be switched off during the measurement. The insulation of the inside of the borehole can be done with a simple plastic pipe, e.g. a ø16 mm installation pipe that is adjusted in length. If this pipe is used, the plugging can be done with a "dibidut no. 17" (plastic plug). Borehole measurements give correct results, but they are very sensitive and in practice - under construction site conditions - can be difficult to perform correctly. The sensor (or a special casing) is placed in the hole and sealed around the sensor with a rubber gasket or similar, see figure 6c. If, before equilibrium is achieved, it is found that the moisture content is increasing and that it is above the permissible level, the measurement can be interrupted, as the moisture content will in any case be too high.

This method allows for repeated recording of the moisture state in the same measuring points. It is thereby possible to follow the change in moisture content over time. The method is recommended for the client's ongoing control of the moisture conditions on the construction site. The temperature in concrete must be in the range 17 - 25°C. As an alternative to the borehole, measurements can be taken in a casing which is already sealed at the desired depth, whereby the waiting time until equilibrium can be reduced. Measurement can also be carried out in embedded pipes. However, embedding pipes can be difficult, as leveling the concrete surface will easily cover or damage the measuring pipe. Furthermore, it is not certain that the measuring tubes are placed where you want to measure.

Laboratory measurements on samples taken
A safer method is to take a sample of the concrete (in the most humid place) and send it to a professional laboratory, where it is placed in a climate chamber. In the climate chamber is achieved after approx. two days an equilibrium state and the relative humidity can now be determined. The samples should be cut up from the floor, with a hammer and chisel, to avoid heating or moisture during drilling. The samples are crushed and placed in glass or plastic containers with lids, or in resealable plastic bags. The volume of broken up material must correspond to approx. ½ coffee cup. The material must be taken at the depth in which the moisture content is to be measured. For concrete decks whose temperature conditions differ from 17-25°C, testing on chipped test pieces is preferable. In such cases, assessment of the tire's moisture conditions should be left to a moisture expert.
Floating mortar and screed
If screeding has taken place on a dry underlying structure, it is only necessary to measure the moisture content of the screed layer. Unless very thick screeds are involved, measurement on a chipped sample is normally used. With thick screeds, measurements can be made in boreholes for approx. 2/3 of the thickness of the screed.
When the humidity level is high
Residual building moisture can be removed by artificial drying. The drying process must take place in a controlled manner, as excessive drying can mean that only the surface dries out and that the construction as a whole is not dried out. Subsequent control of the moisture content at different depths is therefore necessary in connection with artificial drying. If the construction schedules do not allow drying to a moisture level acceptable to the floor covering, a moisture barrier can in some cases be laid out between the concrete and the floor covering. Laying a moisture barrier is specialist work and suppliers and contractors should always be consulted.

3.4 Flatness and floors
Floors should be level in order to:
• Furnishing
• Walking and standing comfort
• Installation of foot panels
• Installation of fixed fixtures
• Aesthetics
• Durability
• Uniform properties

Floors are normally expected to be level and horizontal within certain tolerances. The exception is floors for special purposes, e.g. floors in wet rooms, which in water-stressed areas must be installed with a slope towards the floor drain. The requirements for flatness and horizontality apply to the finished floor. However, many floor covering types will not be able to contribute to an improvement in the flatness of the floor and therefore the requirement for flatness and horizontality will also often apply to the subfloor.

Flatness
Flatness means that all points of the floor lie in the same plane, which can be horizontal or have an incline. Deviations are noted as lumps or elevations. The flatness is desired to ensure that furnishing and movement can take place without problems. The floor must also be level for aesthetic reasons, i.a. installation of baseboards and fixtures must be possible without joints of varying width appearing under panels or fixtures.
Horizontalness
Horizontality means that all points of the floor are both in the same plane and that the plane is horizontal. Deviations are detected as the slope of the floor. Horizontality may be necessary to ensure that furniture or the like. can happen without problems. In order to achieve a level floor, a leveling must often be done, e.g. of the pile height on concrete elements. Such leveling can be extremely expensive if it is to result in a floor that is not only flat but also completely horizontal. In many cases, it will be acceptable that a floor is not completely horizontal, but the floor must not become unusable, e.g. shelves must not lean excessively when placed on the floor. As an example, floors in older properties often have a drop of one percent or more, without being considered unusable for that reason. If a smaller slope, e.g. 0.5%, can be accepted, considerable savings in material and time consumption can often be achieved. It therefore makes good sense to assess how strict the requirements must be for the horizontality of the floor. For example, it should be assessed whether leveling of an arrow height should be done for flatness only, or whether leveling should be done for both flatness and horizontality.
Tolerance
The requirements for flatness must be set in connection with the measured distance. For example, it may be acceptable for a deviation of ± 2 mm to occur within 2 m, while it will be unacceptable if the same deviations occur within 0.25 m. In addition to the requirements for flatness and horizontality, there may be additional requirements for other surface characteristics, see below. Requirements for flatness and horizontality are set in the form of tolerance requirements, i.e. how large deviations from flatness and horizontality, respectively, can be accepted. This is explained in more detail in the following, where first a description is given of the various concepts used in connection with the characterization of floor surfaces, then GSO's measurement method for flatness and horizontality is described, and finally suggestions are given for commonly used tolerances for flatness.

Note that it is important to both agree on which requirements must be met and how they must be measured. If reference is made to different methods, requirements and measurement results will not be comparable. The specified tolerance requirements apply to measurements carried out according to the described method.

Level
If it is required that the floors in neighboring rooms must be at the same level, for example because there is a doorway between the rooms, or because it must be possible to use movable partitions, this must be stated in the tender material, and level markers for use by the flooring contractor must be placed in all rooms.

Terminology
Flatness
Flatness means that all points of the floor lie in the same plane, which can be horizontal or have an incline. Deviations are detected as depressions or elevations, see figure 8.

Figure 8. Measuring flatness with a straightedge of 0.25 m and 2.0 m respectively.

Horizontalness
Horizontality means that the floor is flat and that the plane is horizontal. Deviations are detected as the slope of the floor, see figure 9.

Figure 9. Deviations from horizontality are detected when the floor is tilted.

Local defect
Local defects are understood to mean single defined irregularities, e.g. jumps (difference in level between boards etc.) or burrs (elongated local elevation on the surface), see Figure 10.

Figure 10. Designations for local defects.

Washboard
Slightly larger, regularly repeated bumps. Seen, for example, with moisture-damaged wooden floors, where the boards curve across the width due to expansion of the underside, see figure 11.

Figure 11. Washboard is caused by transversely curved boards.

Tolerance
Tolerance is used to define which limits for deviations are acceptable. A deviation can be either positive or negative. A symmetrical tolerance is normally used, i.e. equal deviations in positive and negative direction are accepted, eg ± 2 mm deviation on flatness. See figure 12.

Figure 12. Measurement of flatness.
Deviations are noted as lumps or elevations.

Measurement of flatness
The flatness of floors is most often determined using a straight edge, for example in the form of an aluminum rail. A straight log with legs is used, the height of which must correspond to the tolerance required by the floor, see the figure for flatness. The legs cause the rectal cavity to be raised above any elevations that lie within the established tolerance requirement. If the elevations become larger, the legs of the retholt will be lifted from the surface. Measuring blocks with a thickness equal to 2 times the tolerance are used to check for gaps, e.g. a 4 mm thick measuring block is used to check a tolerance of ± 2 mm. The block must only be able to pass under the right hole. If there is air between the block and the straight hole, the gap is deeper than the set tolerance requirement. The measuring block can possibly be replaced by a measuring wedge, which makes it possible to measure the actual deviation. Straight bars of 2.0 m are normally used. In special cases, a straight bar of 0.25 m can be used.
Measurement procedure
When measuring flatness, the side of the rectangle that does not have legs is used first. The straight hole is pushed across the floor in a sliding motion from wall to wall. The measurements are made evenly distributed over the floor, but with a preponderance along walls and in front of doors and windows. Measurements are taken in both directions of the room. If the initial measurement reveals unevenness, turn the rectangle so that it rests on the legs. Regardless of the position of the straight hole, it must rest on both legs at all times, and the measuring block must only be able to pass under it. If there is air between the retholt and measuring block, the tolerance requirements have been exceeded.
Tolerance requirements
In the following, suggestions are given for tolerance requirements for different types of floor coverings. If nothing else has been agreed, the proposed requirements can be expected to be complied with. The tolerance requirements are established based on measurement according to the above-mentioned method. In some methods for measuring flatness, measurement of "downstitch" from a straight log without legs is used, and straight logs of other lengths than those mentioned here are used. These methods can be used as alternatives to the proposed one, but in that case the tolerance requirements must also be changed, just as attention must be drawn to the fact that a different measurement method is to be used when tendering.

Both requirements for tolerances, i.e. both too long and too short straight, must be observed. Even when tolerances are met, board joints, trowel strokes and other small irregularities will be visible when thin, smooth coatings are used. This is especially true where there is, for example, stray light from window sections or backlight from spots etc. Polished and varnished surfaces will emphasize unevenness to a greater extent than floor surfaces with low light reflection.

Form 1. Examples of tolerance requirements.

*) Thermoplastic-based floor coverings will always follow the flatness variations of the substrate. See the section: Seamless floors.
**) Flat-woven carpets are defined as a loop-woven carpet or a carpet without pile. Carpets are defined according to ISO 2424 and carpets without pile are classified according to DS/EN 15114.

3.5 Visual assessment of floors
After both new laying and renovation of floor coverings, a check should be carried out to see if the outcome requirements have been met. The inspection should include a visual assessment of the floor, combined with control measurement of the floor's desired flatness and horizontality.

For visual assessment, the following applies:
Assessment of a floor surface for possible faults and defects must take place in normal daylight and at normal eye level (approx. 160 cm above the floor) and in ambient light. The temperature and relative humidity must be stable between 18 and 23° C and 30 and 65% RH. Conditions that must be indicated and are not visible under the previously mentioned conditions are not considered an error. Just as conditions that only appear in special lighting conditions, or can only be observed from certain places in the room, are not considered faults. The use and decoration of the premises (furnishings and lighting) are taken into account in the assessment.

If normal daylight cannot be established or if this is not present in the normal use of the room, the floor must be assessed using artificial light. It is therefore recommended to use lamps that are fitted with tubes or bulbs that emit a light with approx. 6500 Kelvin (1) and approx. 1100-2000 Lux on the subject, no light may be placed with direct light on the subject(s). Halogen lighting must not be used. Halogen lighting shines in a directional manner, and gives a false image, as the light varies greatly from the center to the cone of light. In addition, attention is drawn to the importance of the subfloor. For many semi-hard and jointless coatings, minor inaccuracies in the subfloor will over time appear visible through the top coating. They say they telegraph through the coating. Examples include panel joints between chipboard and fibreboard, putty layers and glue tracks. The importance of the subfloor is further discussed under the different product types. Functional defects and cosmetic defects that are not judged to be negligible must, as a rule, always be corrected.
Read more about tolerance requirements at tolerancer.dk.

3.6 Sound and floors
Sound problems in connection with floors often occur. This is partly due to the fact that the theoretical background for processing sound is complicated, and therefore planning is not always optimal. In addition, the sound conditions are very dependent on the practical implementation. Just a single sound bridge can mean a significant deterioration of the acoustic conditions. In the following, a brief explanation of some sound concepts is given, and some practical aspects of special interest in connection with floors are discussed.

The production is largely based on SBI's instructions on sound, which provide information on most matters. For a more in-depth treatment of the subject, reference is therefore made to:
• SBI guideline 166, "Building acoustics, theory and practice", Jørgen Kristensen and Jens Holger Rindel, SBI, 1989.
• SBI instruction 172, "Sound insulation of buildings, newer buildings", Jørgen Kristensen, SBI, 1992.
• SBI instruction 173 "Sound insulation of buildings, older buildings", Jørgen Kristensen, SBI, 1992.
The publications provide a theoretical review of and practical advice on the sound technical conditions for some typical floor constructions both in new construction and in renovation.

Concepts and terminology
When talking about sound, a number of specific terms are used to describe the sound conditions, e.g. air sound, footstep sound and reverberation time. The most common terms that are important when talking about floors are briefly explained below:
Air sound
The sound that is produced and propagates in the air, for example when we speak and play music, is called airborne sound. If the air sound has to pass through a building structure, it can either be done through openings or by the sound going into the structure and out into the air again on the opposite side of the structure, see figure 13.
(Air) sound insulation
(Air) sound insulation refers to the reduction that occurs when sound is transmitted from one room to another.
Building sound
When the sound propagates inside the building constructions, it is called building sound. Building sound is transmitted through both constructions and installation systems, and the transmission conditions depend on, among other things, of the materials and assemblies used.
Footstep sound
The special building sound that is produced when a person walks on a deck structure and/or a floor is called footsteps. The sound of footsteps propagates directly through the floor separation and any other constructions to the lower and surrounding rooms, see figure 13.

Figure 13. Transmission of airborne sound and footfall sound through floor separations with floating floors. Due to flank transmission, the improvement in air sound insulation is inferior to the improvement in the step sound level.

Footstep sound level
The footfall sound level is a measure of how much sound is transmitted to a neighboring room when the floor of another room is impacted with a standardized knocking machine.
Footstep sound reduction
Footstep sound attenuation is the term for the attenuation (reduction) in the footstep sound level that occurs by providing a deck structure with a floor covering or the like.
Drum sound
Drum sound is the term for the special form of footstep sound, which is emitted in the same room where the impact occurs. Drum sounds are known, for example, from long corridors, where considerable noise can occur when walking.
Absorption
When sound waves hit a building surface, part of the sound energy will be absorbed. This causes the sound pressure level to decrease/the sound to be muffled. The absorption can be used to lower the noise level in a room. Of floor coverings, thick carpets in particular are sound absorbent, but the total sound absorption in a room will usually depend on the surfaces of many different building parts as well as fixtures and people.
Reverberation time
In connection with sound absorption, reverberation time is often spoken of. The reverberation time is an expression of how quickly the sound pressure level in a room falls over time.
Legal requirement
The requirements for the sound conditions of buildings are found in particular in the two building regulations to which reference is made. In addition, there are, for example, sound requirements in the Environmental Protection Agency's guidelines.

Sound insulation of floor separations
The sound insulation of a floor separation depends on the acoustic quality of both the load-bearing part of the floor separation - the deck - and of the floor or floor covering. Floors' impact sound attenuation is calculated in relation to the impact sound level under decks without floor. For concrete decks, impact sound attenuation is largely independent of the deck type. For floating floors, a deterioration of footfall sound absorption of up to 5 dB can occur over time due to compression of the substrate, mostly for floors with high footfall sound absorption. For wooden floor separations, both floating floors and thin floor coverings usually provide significantly less improvement in footfall sound levels than can be achieved with molded decks.

Floor coverings
Hard floor coverings such as terrazzo, concrete wear layers and clinker on cast decks can insulate satisfactorily against airborne sound but not against footstep sound. The same applies to plank floors nailed to wooden joist layers or wooden floors on joists, which are laid out without soft pieces under the blocks. Thin, resilient floor coverings are linoleum, vinyl, polyolefin, cork, rubber and carpets. Of these, cork and especially carpets provide the greatest impact sound reduction. The greatest attenuation is achieved with thick, soft carpets. Linoleum, vinyl, polyolefins and rubber provide only modest attenuation (at high frequencies).

By using soft substrates under the floor coverings, a damping similar to what can be achieved with cork can be achieved, see figure 14.

Figure 14. Example of step sound attenuation of semi-hard flooring on concrete.

While the step sound reduction can be significant for thin floor coverings on hard surfaces, only a modest reduction can be expected under floating floors and wooden floor separations. The reason is that the attenuation of the footfall sound level mainly occurs at high frequencies, while the need for footfall noise reduction under floating floors and wooden floor separations is mainly found at low frequencies.

Figure 15. Examples of step sound dampening properties.

1. Linoleum.
2. Linoleum + cork.
3. Vinyl + foam plastic or felt.
4. Carpeting.

Floating floors - general conditions
Floating floors are understood, in sound engineering terms, as independent floor constructions on top of concrete decks or wooden beams and separated from this and from walls by elastic intermediate layers, e.g. rubber cork, mineral wool or the like. Great step sound attenuation is achieved by high compressibility of the middle layer and a heavy floor construction. Floating floors can be made as wooden floors on joists laid out on soft tiles, or as slab floors made of wood, plaster, asphalt or concrete on elastic substrates of e.g. mineral wool or foam plastic. Floating floors can also be made as board, parquet or laminate floors laid directly on an intermediate layer, which are usually thin special products, e.g. foils with a felt backing, rubber cork or thin foam plastic, but can also be laid with thicker elastic substrates, e.g. foam plastic insulation. In the latter case, the supplier's laying conditions must be strictly observed to ensure sufficient stiffness of the floor slab.

Figure 16. Execution details for step sound dampening of floating floors.

Floating concrete floors are usually cast on 30-50 mm thick substrates. Floating asphalt floors can be made in small thicknesses, approx. 35 mm with underlay, and can at the same time provide significant step sound attenuation. Substrate materials for floating floors must be able to withstand a compression of approx. 10% at the floor's useful load without losing elasticity, and they must not over time undergo excessive deformation as a result of variable load. The greatest step sound attenuation is achieved with substrate materials with high compressibility and with a large thickness.

In contrast to this, there may be a desire for rigid materials with little thickness, if the floor is to be able to be used for heavy loads without being deformed. Footstep sound absorption can be reduced with increasing load on a floating structure, and the reduction in footstep sound absorption will not always disappear when the floor is relieved. It must be avoided to create sound bridges in the form of fixed connections between the floor slab and the supporting structure, as even a single sound bridge will result in a significant reduction of step sound attenuation.
Suppliers of floors and floor coverings can be asked for advice on sound conditions and provide information on step sound attenuation in concrete floor constructions.

Figure 17. Design details that ensure step sound attenuation of screed floors.

3.7 Slip resistance
Slippery floors are dangerous and can lead to falling accidents resulting in personal injury. Falling on the floor is the most frequently reported accident and accounts for approx. 1/6 of all reported accidents.

The above is a fact that cannot be neglected. With the right choice of floor covering, falling accidents can be prevented relatively easily, but it requires that you pay attention to the situation in connection with the choice of the floor covering. The need for slip resistance naturally depends on the way you want to use the floor, and if the floors are wet or greasy, the risk of falling accidents increases significantly. There are no clear rules that define how non-slip/smooth a floor must be in relation to the work functions that must take place on the floor. The safety around the floors is the responsibility of the builder/employer, and must be assessed in relation to the activities that must take place on the floor, as well as in relation to the cleanliness of the floor.

The Norwegian Working Environment Authority can be helpful with an assessment that will be based on the specific work situation, but there are currently no general guidelines. The Norwegian Working Environment Authority writes the following in their "Guidance on prevention of falls on the floor" (AT guidance A.1.6):
The floor covering should have a high slip resistance if there is a risk of spilling liquid and grease. Slip resistance means that the coating provides a lot of friction in relation to the soles of the shoes.

Be aware that the degree of ease of cleaning decreases as the slip resistance increases.

Definitions, concepts and methods.
Friction: Defined as the resistance to movement caused by contact between two surfaces. The resistance to movement will naturally depend on the nature of the surfaces and the weight of the object to be moved. The resistance to movement is often expressed by a coefficient of friction (µ). The coefficient of friction is defined as the ratio between the force that presses on the body (called gravity) and the force required to move the body at a constant defined speed (µ=Ft/Fb).

In connection with floors, one rarely talks about a floor covering's coefficient of friction. The term "slip resistance" of the floor covering is used instead, but it means the same thing. As mentioned before, the coefficient of friction or slip resistance will depend on the nature of the surfaces that are pressed against each other. In order to provide uniform / comparable values, some standardized test methods have been developed for use in such measurements. The most used are DIN 51130, DIN 51097 and EN 13845. The measurements can be carried out on dry or wet surfaces. The results will of course be different and we therefore often talk about the slip resistance in dry and wet conditions respectively.

The ramp test
The most common test is the so-called RAMPE test. The principle of the test is as follows: A piece of the floor covering to be tested is mounted on a movable ramp. A test person wearing shoes with a uniquely defined rubber sole and relevant safety equipment is placed on the ramp. The test person walks on the spot while one end of the ramp is raised. At some point, the test subject will lose his footing. The angle of the ramp is noted, this angle is called the slip angle. The slip angle will be affected by the friction between the test person and the floor covering, and you must therefore be aware that the RAMPE test is carried out in several variants, which are described in different standards. DIN 51130, DIN 51097 and EN 13845 are described below.

DIN 51130: The test person is wearing shoes with well-defined rubber soles. The floor covering on the ramp is lubricated with a lubricant (a well-defined motor oil). The slip angles are recorded and classified in the table below

DIN 51097 is very similar to DIN 51130, but stipulates that the test person is barefoot and that the cleaning agent is soapy water. The classification appears in the table below:

EN 13845 classifies PVC floor coverings with increased slip resistance according to a model very similar to the RAMPE test cf DIN 51130 & 51097. The slip-resistant vinyl is mounted on a ramp that can be tilted. To simulate a wet room/bathroom, liquid (soapy water) must constantly flow over the floor covering with a flow of 6 l/min. The ramp is tilted and the play angle is noted (the angle at which the test subject loses his footing, similar to DIN 51130 & DIN 51097). The test can be performed barefoot or with shoes. Classification and associated criteria appear from the following:

NB: EN 13845 only deals with vinyls with particle reinforced surfaces.

Overview.

The ramp tests are laboratory tests and can only be performed with difficulty on a "real" floor surface. It is not uncommon for there to be uncertainty about how slip-resistant a floor is. The ramp test is not suitable in such situations. In these cases, the so-called PENDULEST test can be advantageously used.

The pendulum tent
The pendulum test is described in several common European standards, including EN 13036 and DS CEN TS 157676. The principle of the pendulum test is that you start a pendulum swing from a horizontal position. The pendulum has a well-defined "sole" on the underside. The arm length of the pendulum is adjusted so that the pendulum just touches the floor in a well-defined area, thereby limiting the upswing.

The height of the "swing" is measured in terms of the angle between the horizontal and the arm at the point where the movement of the arm changes from being upward to being downward; EN 13036 defines 3 slip resistance classes

Pendulum angle (o) 0-24 25-35 >36
Slip resistance class Low Medium High

The connection between the ramp test and the pendulum test

In the section on seamless hard plastic floors, you can read how this type of floor can be made non-slip and similarly, in the section about elastic floor coverings, you can read about how vinyl floors can be made non-slip.

3.8 The flooring industry's digital Quality Assurance
The flooring industry's digital KS tool is not a tool in the traditional sense, i.e. something physical. The tool is a database in which you can find the industry's control plans with corresponding reference to norms and standards for all the building parts that would normally fall under the "Floor" area.

To gain access to the control plans, you must use one of the software packages that have implemented "Gulvbranchens digital KS", because currently two IT companies have access to the database. The technical content of the control plans is prepared by the Flooring Industry's technical committee and is maintained centrally by the Flooring Industry's secretariat. By using "Gulvbranchens digital KS" you ensure that the checks relevant to the task are carried out and documented. The plans must of course be adapted to the specific project. In this process, as a flooring contractor, you must assess whether there are special conditions on the task that must be checked and documented, or whether there are some of the control activities the plans are "born with" that are irrelevant. A process that must also be carried out with traditional KS . Method descriptions have been drawn up for selected control activities to help executors and supervisors. You can find the method descriptions at www.gulvbranchen.dk