How to Install Wood Wool Acoustic Panels: Walls, Ceilings and the Air Gap

Wood wool cement board, known across much of Europe as fibrolite, is one of the most forgiving acoustic materials to install. The panels are rigid, screw straight into place and need no specialist tools. Still, a few decisions made before the first screw goes in decide how good the finished wall or ceiling will look and how well it will absorb sound. This guide walks through them.

Direct fix or battens?

There are two standard ways to mount Sonablock wood wool panels:

• Direct fixing. Panels are screwed straight onto a flat substrate such as plasterboard, OSB, concrete or an existing ceiling. This is the fastest method and works well where the wall behind is solid and reasonably flat.
• On battens with an air gap. Panels are fixed to timber battens or a metal grid, leaving a cavity of 20 to 50 mm behind the board. The cavity can be left empty or filled with mineral wool.

Acoustically, the air gap is the single cheapest upgrade available. A 25 mm panel fixed directly to concrete absorbs well in the speech frequencies, but the same panel mounted with a 30 to 50 mm cavity absorbs noticeably more low-mid energy, because the panel plus cavity acts as a deeper absorber than the panel alone. If the room has a boomy, low rumble problem rather than just echo, choose battens.

Which side faces out?

Wood wool panels have a natural face and a slightly coarser back. The face side is the one with the more even fibre texture. On Sonablock panels the difference is subtle, so check each panel in raking light before fixing, especially with the Natural colour where texture variation shows most.

Fixings and screw pattern

Use screws with a flat, wide head, or dedicated wood wool screws with a small washer head, in a colour close to the panel. For a 600 x 600 panel, four to six screws are enough; a 2400 x 600 panel typically takes eight to ten. Drive the screw until the head sits just flush with the fibre surface. Overdriving crushes the fibres and leaves a visible dimple; underdriving leaves the head proud and catches the eye.

Screw heads in a matching colour practically disappear into the open fibre structure from a metre away. If you want a completely fixing-free look, panels can also be glued to a flat substrate with a construction adhesive suitable for cement-bonded boards, though gluing makes later removal destructive.

Cutting

Wood wool cement board cuts cleanly with a circular saw with a dust extractor, or a hand saw for single cuts. Cut from the face side to keep the visible edge crisp. Edges can be left exposed; the cement-bonded structure does not fray. For a neater junction at walls, a shadow gap of 5 to 10 mm looks better than a forced tight fit, and it forgives walls that are not perfectly straight.

Layout tips

• Dry-lay the first two rows before fixing anything. Panel texture varies slightly, and mixing panels from different pallets evens out the tone.
• Keep a consistent joint width. Chamfered edges give a tidy, tile-like grid that hides small alignment errors.
• On ceilings, start from the centre of the room and work outwards so cut panels land symmetrically at the edges.
• Leave the panels in the room for 48 hours before installation so they acclimatise to the humidity level they will live at.

What you do not need

No wet trades, no skim coat, no acoustic fabric stretching. This is where wood wool differs from many acoustic systems: the panel is the finish. Once it is screwed up, the job is done, and a damaged panel years later can be unscrewed and swapped in minutes.

Sonablock panels by Stiga RM come in 15 mm and 25 mm thicknesses, sizes from 600 x 600 up to 2400 x 600 mm, five standard colours and a B-s1,d0 fire classification. Browse the range in our wood wool acoustic panel collection, and if your project has an unusual substrate or you are unsure about direct fix vs battens, write to us and we will help you spec it.