Sound insulation · Stone wool
ROCKWOOL Safe 'n' Silent Pro
- Thickness
- 25–100 mm
- Density
- 40–100 kg/m³
- Sound absorption (NRC)
- 0.90–1.00
How do you choose wall insulation?
In short
Start from the goal: reducing heat through an external wall, or reducing sound through a wall between rooms. Then look at the wall type: a framed drywall partition has a cavity for insulation boards, while a brick or block wall usually needs an extra framed lining to make room for insulation. Then check moisture and fire requirements. Sound insulation is a result of the whole wall system, not of the insulation alone.
1. What is the goal?
| Goal | Walls usually involved | Value to compare |
|---|---|---|
| --- | --- | --- |
| Less heat entering the room | Sun-facing external walls, walls of air-conditioned rooms | Insulation R-value at the real thickness, and the whole wall's U-value |
| Less sound passing between rooms | Bedroom, meeting-room and plant-room partitions, walls between units | STC / Rw of a tested wall system |
| Both | External walls facing a road, plant rooms next to air-conditioned rooms | Check both |
If the house is hot mainly because of heat from the roof, wall insulation may not be the first step. See Hot house and How heat enters buildings. If the problem is echo rather than sound through the wall, see Room echo.
2. Framed drywall or masonry?
Framed drywall
Gypsum or fibre-cement boards on steel or timber studs already have a cavity, so stone wool or glass wool boards fit in easily — for example ROCKWOOL Safe 'n' Silent Pro or SCG Cylence ZoundBlock. Fill the cavity completely, without gaps, following the manufacturer's guide. See Installing insulation in drywall.
Brick or block walls
A solid masonry wall has no cavity for insulation. The usual option is to add a framed lining or second leaf and put insulation inside it, which takes up some room space. For sound insulation, the result depends on isolating the new layer from the existing wall, the cavity depth and sealing of gaps; details should be set by a designer or specialist.
External walls with an air space
Reflective foil such as Eskimo Foil 101F, or PE foam with a metalised film such as M-PE Standard, can be used in wall cavities where the manufacturer says so. A reflective surface only works with an air space in front of it. See Reflective foil.
3. Sound-insulating walls: insulation is one part of the system
Cavity insulation absorbs sound bouncing inside the cavity, but a wall's sound insulation comes from several parts together:
- Mass of the boards and number of layers
- Isolation of the two faces — research by the National Research Council Canada shows that if both faces are rigidly connected, cavity insulation helps very little
- Cavity depth and amount of insulation
- Sealing around wall edges, ceilings, sockets, switches and pipe penetrations
- Flanking paths through ceilings, floors or structure. See Flanking sound
Use the STC / Rw of a wall system the manufacturer has tested and fully described, and build to those details. Read more in How cavity insulation helps sound insulation and STC / Rw.
4. Moisture
- In external walls in a hot, humid climate with air-conditioned rooms inside, water vapour tends to move from outside inwards. Building-science guidance advises against vapour barriers such as polyethylene sheet on the inside of air-conditioned walls, so the position of foil facings or vapour-control layers should be decided with the designer. See Vapour barrier and Dew point and condensation
- For bathroom walls or wet areas, choose insulation and boards that the manufacturer states are suitable for damp areas
- Keep insulation dry before installation, and do not close a wall over wet insulation
5. Fire requirements
- Check what the drawings or building regulations require for that wall, such as escape-route walls or fire compartment walls
- Non-combustibility (e.g. stone wool classified to EN 13501-1) is a property of the material; a fire-resistance period in hours belongs to a wall system tested as a whole. See Fire performance terms
- For fire-resisting walls, use a system with test evidence and have a specialist specify it
Common mistakes
- Filling a drywall cavity but not sealing gaps, socket boxes or the top edge under the ceiling
- Fixing sound-absorbing panels on a wall to fix noise from next door
- Leaving the cavity partly empty, or stuffing it until boards are crushed. See Gaps and compression
- Quoting the STC of a documented wall system for a wall built differently from the tested one
See solutions: Neighbour noise · Machine noise · Hot house
Sources
- National Research Council Canada (IRC) — Control of Sound Transmission through Gypsum Board Walls
- Building Science Corporation — BSD-106: Understanding Vapor Barriers
- Building Science Corporation — Info-501: Installation of Cavity Insulation
- ROCKWOOL — Safe 'n' Silent Pro data sheet and product page
- SCG — SCG Cylence ZoundBlock installation guide and SCG Acoustic catalogue
- EN 13501-1 — Fire classification of construction products and building elements: reaction to fire
Related products
Categories and example products for this topic
- ROCKWOOL Safe 'n' Silent Pro — Sound walls: stone wool slab for drywall cavities, in four density grades
- SCG Cylence ZoundBlock — Sound walls: glass wool in a moisture-barrier wrap, 50 and 100 mm, for wall cavities
- ESKIMO FOIL 101F — Heat through walls: double-sided foil for wall cavities; needs an air space at the foil
- M-PE (Standard) — Heat through walls: closed-cell PE foam with metalized film, light and easy to install
Sound insulation · Glass wool
SCG Cylence ZoundBlock
- Thickness
- 50–100 mm
- Density
- 32 kg/m³
- Thermal conductivity (λ)
- ≤ 0.033 W/m·K
Building thermal insulation · PE foam
M-PE M-PE (Standard)
- Thickness
- 3–20 mm
- Density
- 35–45 kg/m³
- Thermal conductivity (λ)
- 0.029 W/m·K