Stone wool vs glass wool — what is the difference?

5 min read · Written by our team · Updated 26 Sept 2026

A grey-brown stone wool slab standing next to a pale yellow glass wool roll, with a red heat arrow approaching.

In short

Stone wool (rock wool) is made by melting rock and spinning it into fibres; glass wool (fibreglass) is made the same way from molten glass. Both insulate against heat and help with acoustics. The differences worth checking are maximum service temperature, density, product form and where it will be installed — look at the actual values of each product in the maker's documents rather than choosing by material name alone.

1Raw material: glass wool uses glass (including recycled glass) and sand; stone wool uses volcanic rock such as basalt — proportions vary by manufacturer
2Melted at high temperature and spun into fibres
3Formed into rolls, boards or pipe sections — check each product's datasheet for its actual properties; colours here only tell the materials apart

General comparison

	Stone wool	Glass wool
---	---	---
Raw material	Molten rock (e.g. volcanic rock)	Molten glass
Common names	Stone wool, rock wool, Rockwool	Glass wool, fibreglass
Typical forms	Slabs, rolls, wired mats, pipe sections	Rolls, boards, pipe sections
Often used for	Acoustic wall infill, high-temperature and fire work	Roofs, ceilings, ductwork, pipes

This table shows general tendencies. Each product has its own values — check the manufacturer's documents.

How to choose

High-temperature or fire work — check the maximum service temperature and the fire test results
Acoustic walls — check that the maker specifies it for tested wall systems
Roofs and ceilings — compare λ, thickness and facing
Ductwork — use products made specifically for ducts