Underfloor Heating Velcro System Slim vs. Silent – Which variant is ri

Q: What is the difference between Hook & Loop Slim and Silent?

Hook-and-loop system Slim (2 mm) is the standard version without sound insulation, construction height from 26 mm, price €6.00/m². Hook-and-loop system Silent (5 mm) has integrated impact sound insulation of 28 dB (Delta Lw), construction height from 29 mm, price €9.99/m². Installation is identical for both.

Q: Does the Klett system Silent meet the DIN 4109 sound insulation requirements?

Yes. The Klett Silent system reduces impact sound by 28 dB (Delta Lw). In combination with an 18-cm raw concrete ceiling, the impact sound level drops from approx. 72 dB to approx. 44 dB — thus falling below the DIN 4109 limit of 46 dB. MC Therm provides technical data sheets for sound insulation verification.

Q: How much thicker is Silent compared to Slim?

Silent is 5 mm thick, Slim is 2 mm thick — a difference of 3 mm. In terms of overall structure, this means: Slim from 26 mm, Silent from 29 mm. For floor construction, 3 mm is often negligible, but can be relevant at doors or stair treads.

Q: Can I use the Silent Hook and Loop System in a single-family home?

Yes, technically no problem. In a single-family house, Silent is not absolutely necessary (no DIN 4109 requirement), but those who desire increased impact sound insulation between the ground and upper floors—e.g., with small children or a home cinema—will benefit from the 28 dB insulation performance. The additional cost is €3.99/m² compared to Slim.

Q: Is laying Slim and Silent equally complicated?

Yes, identical. Both variants are laid by pressing the PE-RT heating pipe into the hook and loop fleece—no tools, no clipping. The laying speed for both is 20–30 m²/h. Only the fleece itself differs in thickness and sound insulation function.

Q: Which heating pipe fits the Slim and Silent hook-and-loop system?

Both versions use the same KLETT PE-RT EVOH heating pipe in dimensions 14×2 mm or 16×2 mm. The pipe is pressed identically into both fleece types. 14×2 mm is preferred for minimal installation height, 16×2 mm for higher heating output (lower flow resistance).

Q: Is there a complete set with Silent Fleece?

The complete Velcro system set (€120.88 / 10 m²) contains the Slim fleece. For silent projects, individual purchase is recommended: Silent fleece (€99.89 / 10 m²) + VELCRO PE-RT pipe (€129.75 / 200 m) + edge insulation strips (€50.65 / 20 m). This allows the silent components to be specifically planned for rooms with sound insulation requirements.

Hook and Loop System Slim vs. Silent: Which Hook and Loop Fleece Variant is the Right One?

The hook-and-loop system is available in two versions: Slim (2 mm, from 26 mm total height) and Silent (5 mm, 28 dB impact sound insulation according to DIN 4109, from 29 mm height). The price difference is €3.99/m². This guide explains the technical differences and shows when each version is the right choice.

⏱ 7 min. read

Silent: 28 dB DIN 4109

Slim: Installation height from 26 mm

Pre-purchase decision-making aid

When is which variant suitable?

→For detached/terraced houses without sound insulation requirements: Is the Slim hook-and-loop system (2 mm) sufficient?
→For multi-family homes/rental apartments with DIN 4109: Silent hook-and-loop system (5 mm) necessary
→Maximum installation height known (determines Slim vs. Silent)
→Floor covering plan available (tiles, parquet, vinyl)

Slim and Silent: Similarities & Differences

The Slim and Silent hook-and-loop systems differ in one single, but crucial, characteristic: the thickness of the fleece and the resulting sound insulation function. Everything else — installation principle, compatible heating pipe, suitability for floor coverings, compatibility with heat pumps — is identical. This makes the system choice clear: if sound insulation is required (DIN 4109, multi-family house) → Silent. If no sound insulation is required, and minimal installation height is desired → Slim.

The 5 most important comparison points

Technical differences at a glance: Hook-and-loop system Slim: 2 mm fleece thickness, total height from 26 mm (with 14 mm pipe + 10 mm screed). No sound insulation function. Price: €6.00/m². — Hook-and-loop system Silent: 5 mm fleece thickness, impact sound insulation Delta Lw = 28 dB, total height from 29 mm. Price: €9.99/m². Both variants are installed in the same way: roll out the fleece, press in the pipe, apply the screed. The heating pipe (HOOK-AND-LOOP PE-RT EVOH 14×2 mm or 16×2 mm) is identical for both.

Acoustic Insulation with Silent Hook-and-Loop System: What does 28 dB mean?: 28 dB impact sound reduction (Delta Lw) sounds abstract – in practice, it means that noises from footsteps, falling objects, and rolling chairs are perceived significantly more quietly on the floor below. DIN 4109 requires a weighted normalized impact sound level L'n,w ≤ 46 dB in multi-family homes. A typical 18-cm concrete ceiling without sound insulation has L'n,w ≈ 72 dB. With the Klettsystem Silent, the value drops to approx. 44 dB – thus meeting DIN 4109. Slim (without sound insulation function) would only marginally improve the value.

Overall height: Why every millimeter counts: In old buildings and during modernizations, the available installation height is often limited. The Hook & Loop Slim system (2 mm) saves exactly 3 mm compared to Silent (5 mm). This may sound like a small amount, but it can be crucial for doors, stair landings, and transitions to other floor coverings. In new builds with more generous planning, the 3 mm difference is usually irrelevant. Rule of thumb: If the installation height must be under 30 mm, choose Slim. If sound insulation is required, Silent is the right choice regardless of the installation height.

Decision Matrix: Slim or Silent?: Choose the Slim hook-and-loop system if: (1) Single-family home or townhouse without sound insulation requirements, (2) minimal installation height required (< 30 mm), (3) budget optimization is a priority. — Choose the Silent hook-and-loop system if: (1) Multi-family home or rental apartment with DIN 4109 requirements, (2) sound insulation desired against neighbors or other occupants, (3) installation height of 29–31 mm is acceptable. Both variants are installed identically and can be combined in the same building on different floors or in different apartments.

Combination: Slim and Silent in the same building: In practice, many builders and planners use both variants: ground floor (single-family home, no sound insulation necessary) → Slim; upper floor above the living area → Silent. This way, the budget is used efficiently: only where DIN 4109 applies or sound insulation is desired is the more expensive Silent variant used. Since fleece and pipe are laid identically, planning and logistics efforts are minimal.