


Heka Acoustic panel Relief
Relief is a panel with a sculpted surface. Grooves cut into 24 mm felt form a three-dimensional pattern of lines, waves, circles or rhombuses.
This gives the surface a larger developed area and breaks up reflections at varying angles, which helps above all in rooms with parallel walls. Visually it reads as an architectural element rather than a technical lining.
It suits prestigious meeting rooms, lobbies and executive areas. We can adapt the pattern to the architect's drawing, including a company logo.
Key features
- 24 mm thick, V-groove 10 mm wide and up to 18 mm deep
- Four standard patterns: lines, waves, circles and rhombus
- Pattern to the architect's drawing on request
- Sizes up to 2400 × 1200 mm, made to measure in 10 mm increments
- NRC 0.80 to ASTM C423-22 for 24 mm felt
- Ten felt colours from the standard palette
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Technical data — Relief
Materials and construction
Material: 100 % polyester (PET felt), with at least 60 % recycled content from used bottles according to supplier data. The boards are fully recyclable.
Density: 9 mm approximately 1,900 g/m², 12 mm approximately 2,400 g/m², 24 mm from 3,500 to 4,000 g/m².
Fire classification: EN 13501-1, class B-s1,d0 according to the supplier's certificate (for individual batches B-s2,d0 — the certificate for the particular batch is supplied with the delivery).
Emissions: OEKO-TEX Standard 100 and REACH, formaldehyde-free, low emissions of volatile organic compounds.
Thickness: 24 mm. Machining: CNC V-groove 10 mm wide and up to 18 mm deep. Largest board: 2400 × 1200 mm.
Acoustics and absorption
24 mm felt, board directly on the wall (ASTM C423-22): αs 0.25 / 0.45 / 0.88 / 1.06 / 0.85 / 0.97 at 125, 250, 500, 1000, 2000 and 4000 Hz. NRC 0.80, SAA 0.82. To ISO 11654 this is αw 0.55, class D.
With a 50 mm air gap: αw 0.65, class C. With a 100 mm gap: αw 0.90, class A. With a 200 mm gap: αw 0.95, class A.
An honest note: the cut pattern enlarges the developed surface and scatters reflections, but for this exact groove profile we do not yet have our own measurement to ISO 354. We therefore quote the values of smooth 24 mm felt and do not count the pattern towards absorption. Where a project calls for a proven class, we reach it with an air gap or with infill behind the panel.
The values quoted come from the data sheets of the PET felt, measured to ISO 354:2003 or ASTM C423-22 and classified to ISO 11654:1997. They apply to material of this thickness in the mounting described. For a specific room we prepare a reverberation time calculation based on the floor plan.
Installation
Adhesive pads: the board sits on the wall, with no air gap.
25 mm spacers: the basic gap, which improves absorption at mid frequencies.
Substructure with a 50 to 100 mm gap: the version for projects that require class C or A. The substructure is priced separately.
Magnetic brackets: a removable version for rented premises.
The pattern runs across the joint between two boards, so state the total width of the wall when ordering. We set out the layout so that the lines line up.
Care and cleaning
In normal use the felt needs no special care. Vacuum it regularly with an upholstery nozzle or clean it with a soft brush, roughly twice a year.
Remove individual stains with a slightly damp cloth and a mild detergent, then let the surface air-dry. Do not use aggressive cleaning agents, solvents or steam cleaners.
A damaged board can be replaced on its own, so the pattern does not have to be renewed as a whole.
Delivery and lead times
Standard sizes: production and delivery 2 to 3 weeks.
Made to measure: 4 to 6 weeks, depending on the size of the order.
Delivery: Slovenia and the EU with our own vehicles or through a forwarder. For larger projects we agree floor-by-floor delivery and an installation schedule.
Returns: 14 days for standard products in line with the law. Made-to-measure products are excluded.
PROJECT SUPPORT
For architects and specifiers
Acoustics are decided at the design stage, not when the space is handed over. We send architects and specifiers data sheets, an absorption calculation for the actual floor plan and drawings to place in the project.
CAD, DWG and data sheet
We send drawings and data sheets for the project documentation on request.
Absorption calculation
Send the floor plan and the room height to sales@heka-interior.com. We will prepare a coverage proposal and an estimate of the reverberation time.
Colour samples
We send the felt sample set free of charge, so that you can confirm the colour in the light of the room before the project goes on site.
Volume discounts
On projects with a pattern to drawing we include the preparation and a trial section of the wall.
Documentation and samples
Everything you need to decide, or to place the product in your project.
Data sheet — Relief
Dimensions, absorption by frequency, materials and fire classification data.
CAD and DWG
Drawings to place in a floor plan or in project documentation. Sent on request.
Felt colour sample set
Ten colours from the standard palette. We send the samples free of charge, so that you can confirm the colour in the room.
Standard patterns
Board thickness in mm
Largest board in mm
Felt colours
Frequently asked questions
Which pattern should I choose?
Lines look calm and make the room appear taller. Waves soften the strict geometry of a meeting room. Circles and rhombus are more pronounced, and we recommend them on one feature wall rather than on all of them.
Can you cut our logo?
Yes, from a drawing in vector format. The pattern preparation and the machine time are priced in the quotation; send your request to sales@heka-interior.com.
Does dust collect in the grooves?
The grooves collect about as little dust as smooth felt does. You vacuum them with a narrow nozzle along the groove, roughly twice a year.
How large is the largest board?
2400 × 1200 mm. Larger walls are made up of several boards, and we place the joints so that the pattern carries on across them.
Is Relief more effective than a smooth panel?
The developed surface is larger and the reflections scatter more, but for our groove profile we do not yet have our own measurement. We therefore sell it with the values of smooth 24 mm felt. The measurable difference is made by the air gap behind the panel.
Is it available in a thinner version?
No. The V-groove requires a 24 mm base, otherwise the grooves would cut through the board. For thinner wall finishes use the Kvadro panel.
Haven't found your answer?
Write to sales@heka-interior.com or call +386 1 361 90 28. We answer inquiries within one working day.
What you get besides the product
Acoustics are a project, not an item. That is why, along with the boards, you get a calculation, samples and someone to talk to who also manufactures the product.
Our own production
Cutting to size, edge finishing and final work are carried out in the Hit Preless production facility in Medvode, and the felt is sourced from proven suppliers. That is why a custom size is the rule, not the exception.
Recycled PET felt
The material is made of recycled polyester, free of formaldehyde and with low emissions of volatile compounds. At the end of its life it is recyclable.
Honest figures
We publish the absorption both without an air gap and with one. The difference between the two classes is made by the installation, not by an advertising figure.
OUR OWN PRODUCTION
Made in a production facility that fits out entire buildings
Heka Interior is a brand of Hit Preless from Medvode. In the same production facility where bespoke furniture for offices and hotels is made, we also manufacture acoustic wall finishes. That is why special sizes, lengths and versions are feasible even in small batches.










































NEXT STEP
Do you have an architect's drawing?
Send the floor plan and the room height to sales@heka-interior.com or call +386 1 361 90 28. We will prepare a coverage proposal, an absorption calculation and a quotation with a volume discount.

