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Sempatap supports you from A to Z in your renovation and insulation projects, to help you make the right choices and ensure the success of your thermal insulation, sound insulation and sound absorption works. 

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  • Sound absorption
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Sound absorption

1) What is sound absorption?

The purpose of sound absorption is to reduce or control the propagation of sounds within a room. It therefore helps to:

  • limit sound reverberation
  • reduce echoes
  • reduce the level of the sound wave
  • improve intelligibility of speech in a room

The sound absorption of materials is described by an absorption coefficient (αw).
The closer the αw is to 1, the more absorbent the material. The closer the αw is to 0, the less absorbent the material, meaning that the sound is totally reflected. Therefore, a material with an absorption coefficient of αw=0.8 absorbs 80% of incoming sound.

Discover Sempatap's sound absorption products. 

2) What is the difference between sound absorption and sound insulation?

Sound insulation refers to all of the measures aiming to reduce exchanges of noise nuisance between the outside and inside of a premises, and from one room to another.

Sound absorption deals with sounds reflected within a room. It reduces reverberation and the level of the sound wave within the room, for improved listening comfort.

Discover the SempaPhon range of sound insulation products

Discover the SempaTap range of sound absorption products

If you're not sure which solution to use, the Sempatap team is on hand to help you identify your needs and advise you on the most suitable product.

3) What is acoustic comfort?

Sound regulations for buildings aim to ensure a good sound environment, and impose limits for:

  • Reverberation in premises (resonance effect of a building or room)
  • Noise insulation against external airborne noise (road, rail or air traffic) and internal noise (conversations, television, hi-fi), impact noise (moving furniture, dropped objects) and equipment noise (lifts, plumbing, ventilation).

These regulations apply particularly in the renovation of public spaces, with (in France) minimum acoustic treatment sound absorption of 25% (alpha sabine absorption coefficient = 0.25). In new construction in France, thermal and acoustic requirements are defined in the RT 2020 or NRA standards.

For improved acoustic comfort, discover the SempaTap® range of absorbent products.

4) What is reverberation?

Reverberation is the persistence of a sound after the source of the sound stops, due to multiple reflections from the walls or contents of a space.

5) What is an echo effect?

Echo and reverberation are often confused, but they are two completely separate phenomena. In the case of reverberation, the reflected sounds are spaced at very short intervals, so the ear cannot differentiate one sound from the last.

An echo is the reflection of a sound wave which repeats itself, and reaches the ear of the listener after a certain interval. Thus, the separation time between the two sounds is long, and the ear hears the repetitions clearly.

Discover SempaTap® sound absorption products to correct the echo effect.

6) Qu’est-ce que la fréquence ?

Frequency determines the pitch of a sound and is measured in Hertz (Hz). A low frequency produces a deep sound, a high-frequency produces a high-pitched sound. We can therefore distinguish 3 types of frequencies:

  • low frequencies (20 to 400 Hz)
  • medium frequencies (400 to 1600 Hz)
  • high frequencies (1600 to 20,000 Hz)

7) Where does the absorbent power of Sempatap products come from?

Sempatap has developed Wraptech®, an innovative technology that allows latex to be mixed to create multiple alveoli. The air contained in these pockets absorbs noise nuisance.

Sound insulation

1) What is sound?

Sound is the emission of sound vibrations which are audible to humans. These are characterised according to their mode of transmission (airborne or through the structure of the building itself) and their origin (impact, environment or equipment).

The common unit for measuring sound is the decibel (dB). We use a sound scale going from 0 dB (audibility limit) to 130 dB (pain limit). Most sounds in everyday life are between 30 and 90 decibels. Levels over 90 dB are primarily found in professional life, particularly in industry and construction.

2) What is sound insulation?

Sound insulation aims to reduce or stop the propagation of sounds between two spaces. This means protecting against noise nuisance from outside the premises (sourroundings, terraced or semi-detached house) or protecting the surroundings against noise produced oneself or through professional activity.

3) How is sound insulation performance measured?

Sound insulation is not described for a single material, but through comparison with and without insulation. In other words, it involves measuring the values before and after treatment.

For Sempatap to offer you the ideal solution to your problem, you need to:

  • identify the nature of the noise (voices, impact)
  • locate the origin of the noise (machine, television)
  • identify the nature of the walls or partitions to be treated (hollow bricks, concrete, honeycomb partitions, plasterboard, wood floor or slab floor, etc.)

4) Which Sempatap product guarantees good sound insulation?

Sempatap offers various sound insulation solutions adapted to walls or floors, to protect you, and to protect those around you against noise from inside.

Sempatap has designed SempaPhon® ISO, an anti-noise barrier to stop the diffusion of noise through the structure of the building, using the "Mass-Spring-Mass" principle. SempaPhon® ISO has the advantage of being a particularly effective form of insulation relative to its thickness, compared with existing partition solutions. The SempaPhon® ISO range guarantees very good performance with a very low thickness.

To see the characteristics of SempaPhon® ISO, click here.

5) What is the difference between sound insulation and sound absorption?

The sound insulation of a wall prevents sound passing from one side of the wall to the other. The objective is to minimise the sound heard on the other side to the noise source. This is the purpose of SempaPhon®, which helps to stop noise passing from one room to the next, or to the surrounding area (impact noise Delta dB).

Discover the SempaPhon ISO range

SempaFloor® solutions are designed to reduce floor impact noise.

Discover the SempaFloor® range

Remember: sound absorption absorbs the sound generated in a room, to reduce the echo or reverberation time. This is the purpose of the SempaTap® range, which provides sound absorption and more.

Discover the SempaTap® range

Thermal insulation

1) What is thermal insulation?

Thermal insulation refers to all the products and techniques that help to reduce or eliminate heat loss between two environments of different temperatures. It also improves comfort in both summer and winter.

Thermal insulation work involves treating the walls, floors or ceilings of a building, to minimise the amount of internal heat escaping to the outside.

Discover Sempatap's buildings solutions for walls, floors and ceilings

2) What are the advantages of sempatap thermal insulation?

Sempatap's thermal insulation products offer excellent quality, because, among other benefits, they help to:

  • limit heat loss associated with thermal bridges
  • save energy
  • improve everyday thermal comfort
  • protect a building against premature ageing
  • add value to real estate assets
  • reduce your environmental footprint by limiting greenhouse gas emissions

3) How do I know if my house is well insulated?

Before conducting energy renovation works, it is important to recognise the signs of poor insulation.

A building is poorly insulated if, in winter:

  • the walls and floors are abnormally cold,
  • certain rooms are harder to heat than others,
  • you can feel drafts,
  • the heating costs are too high,
  • mould develops on internal walls.

In summer, poor insulation leads to:

  • high air conditioning costs,
  • the air inside being constantly too hot.

To be sure, it is simplest to call a professional, who can carry out a thermal diagnosis on your home.

4) What is a thermal bridge?

A thermal bridge is a structural element where the thermal resistance is not homogeneous because of differences in materials or structural problems in a building. Consequently, heat loss can seriously increase energy bills.

Thermal bridges can be found at different points in a home:

  • wall/ceiling join
  • wall/roof join
  • window frames
  • openings in the roof…

The majority of thermal bridges are not visible to the naked eye. However, the appearance of damp stains or the formation of condensation can indicate the presence of certain thermal bridges. A specialist assessment is therefore recommended.

5) What is heat loss?

Heat loss refers to the loss of heat from one environment relative to another. According to ADEME, the main sources of heat loss are:

  • roofs and attics (25 to 30%)
  • walls (20 to 25%)
  • windows and glazing (10 to 15%)
  • low floors (7 to 10%)

6) What is thermal conductivity?

Thermal conductivity refers to how well a material conducts or insulates heat. Written λ (lambda), it is measured in W/m.K (Watts per metre-Kelvin).

Note: the higher the conductivity (high λ), the more the material lets heat through. Conversely, the lower the conductivity (low λ), the more insulative the material.

7) What is thermal resistance?

Along with thermal conductivity, thermal resistance is one of the indicators of insulation performance.

Thermal resistance is usually indicated by the letter R, and measured in m².K/W (kelvins per watt). It indicates the capacity of thermal insulation to resist temperature differences: the higher the thermal resistance (R), the more effective the insulation. This thermal resistance is directly proportional to the thickness of the product.

This is the case of SempaTap® 10mm, with its R=0.0212, characterising it as thin insulation or low-thickness insulation with high performance. Note that for the same thickness, Sempatap and rock wool will have equivalent thermal resistances.

8) Which Sempatap product guarantees good thermal insulation?

The products in the SempaTap® range are low-thickness solutions with low thermal conductivity, characteristic of excellent insulation materials.

This is why the products in the SempaTap® range are recommended for insulating walls and ceilings, because they considerably reduce heat loss in winter and provide a pleasant and well regulated room temperature in summer.

To discover the whole SempaTap® range, click here.

Questions/answers for a successful preparation, application and pasting of Sempatap products.

  • Preparation
  • Installation
  • Pasting

Sempatap's recommendations for successful preparation

Note: before applying the product, always ensure that the walls or ceilings are clean and dry. This is essential for successful installation of your Sempatap insulation.

1) For plasterboard walls

For plasterboard walls, it is sufficient to apply a primer paint.

2) For wallpapered walls

For wallpapered walls, it is first necessary to remove the existing wallpaper and treat the wall with a primer.

3) For cracked walls

It is essential to fix cracks in the walls: open up the cracks and refill them by applying a filler. It is advisable to cover the surface to be treated with our specific renovation product SempaTap RENOV. The wider and deeper the cracks, even if filled, the more important it is to choose a higher grammage of SempaTap RENOV.

4) For painted walls

The products must be applied to a sound, clean and dry surface.

For painted walls, it is vital to wash and rinse them, to remove any traces of dirt, grease or mould.

For glycerophtalic (alkyd) paint, it is possible to use SempaFix T20 (Sempatap KLEBER) adhesive, diluted in 20% water. Apply the SempaFix T20 diluted adhesive mixture using a roller and leave to dry for 24 hours before putting the covering on.

Sempatap's recommendations for successful installation

1) How do I cut Sempatap products?

Equipment required: a cutter with a new blade.

Be careful with the angle of the cutter blade: choose a very low cutting angle of around 10°. For perfect results, use a spatula or metal ruler to guide the cutter along the wall or into corners.

2) How do I join the strips?

Technique 1: Butt joint
The "butt joint" technique involves placing them side-by-side.

Technique 2: Double cut

  • Step 1: Place the strip for application so that it overlaps with the preceding strip by around 4 cm.
  • Step 2: Cut the two strips 2 cm from the edge (in the centre of the overlap) with a cutter, resting against a ruler.
  • Step 3: Remove the cut parts and place the edges of the strips together, so that they join perfectly.

In the event of an application error, whatever your joining technique, remove the strip and put it back on immediately.

3) How do I avoid air bubbles?

During the application phase, it is necessary to smooth the product carefully, to avoid air bubbles getting trapped. Press the covering down using a plastic spatula in a vertical direction, starting from the centre and moving towards the edges.

4) What is the drying time?

Before applying paint or wallpaper, allow Sempatap coverings to dry for:

  • 48 hours on absorbent surface (e.g. plasterboard)
  • 4 to 5 days for a non-absorbent surface

Sempatap's recommendations for successful pasting

1) Which side should I put my adhesive on?

Whatever the Sempatap product, apply the foam side of the covering to the surface you are treating.

2) What adhesive should I use?

Choosing the right adhesive is essential for successful application of an insulative wall, floor or ceiling covering.

To find out which to use, please refer to the product application instructions.

If you have any questions, ask the Sempatap team for advice by clicking here.

3) What spatula should I use to apply sempatap, sempaphon and sempafloor products?

For products in the SempaTap, SempaPhon and SempaFloor ranges, choose an A2 spatula.
Grooved A2 spatula: 400 to 500 g/m² consumption.

Useful notes:

  • Grooved A3 spatula: 600 to 700 g/m² consumption.
  • Grooved A4 spatula: 800 to 900 g/m² consumption.
  • Grooved A5 spatula: 300 g/m² consumption

4) How do I ensure that the adhesive sticks well to the surface?

To ensure that the adhesive sticks well:

  • prepare the surface appropriately: dust and clean off traces of grease and dirt, roughen overly smooth surfaces,
  • spread a uniform layer of adhesive (the spatula will allow you to get the right quantity per m²),
  • use vigorous and even pressure using the smoothing technique.

5) What is the activation time?

The activation time refers to the time needed for evaporation of the water contained in the adhesive before final assembly.

For Sempatap products, this is 5 to 10 minutes at a temperature of 20°C

To find out the activation time on your site, use the following test: touch the freshly spread adhesive. When this starts to form thin filaments between the surface and the finger, optimum activation time has been reached.

6) How do I remove adhesive marks?

If the adhesive is fresh, act immediately before it dries. To remove it:

  • take a clean cloth
  • dip it in lukewarm water
  • gently rub until the mark has been removed

7) How do I clean my tools?

Before the adhesive dries, wash your tools in clean water.