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Envelope and protection

Insulation Materials

Insulation only works as part of a build-up. The same board in two different walls can behave very differently depending on what sits either side of it, how continuously it is installed, whether air can bypass it and how moisture moves through the assembly.

These entries describe what each insulation material is and the topics that surround it — moisture behaviour, air movement, fitting tolerance, compatibility with adjacent layers. They contain no thermal calculations, no performance figures and no claim that any material will deliver a given energy outcome. Those are matters for a qualified professional working on the actual build-up.

14 reference entries · educational materials reference · suitability always depends on the complete assembly and qualified professional review

Scope

What this category covers

Where the boundary of this part of the library sits, including what it deliberately leaves to qualified professionals.

  • Mineral, glass, natural-fibre, foam and reflective insulation materials
  • Insulation formats: batts, rolls, boards, blown, sprayed and panel systems
  • Composite systems where insulation is combined with a finish
  • Not covered: U-value or thermal calculations, condensation risk analysis, energy modelling

Start here

Frequently referenced entries

A starting point, not a ranking — these are simply the entries most people arrive looking for.

Mineral wool insulation →Fibrous insulation spun from melted rock and mineral feedstock, supplied as rolls, semi-rigid batts, rigid slabs and loose fill for walls, roofs, floors and partitions.Polyisocyanurate board →Rigid faced foam board formed by reacting isocyanate with polyol, produced continuously between bonded facings and used in roofs, walls, floors and insulated linings.Wood fibre insulation →Insulation made from defibred wood, supplied as flexible batts and as rigid boards, including profiled grades intended to be built into sheathing and sarking positions.

All entries

Every insulation entry

The complete set for this category, in reference order.

Mineral wool insulation →Fibrous insulation spun from melted rock and mineral feedstock, supplied as rolls, semi-rigid batts, rigid slabs and loose fill for walls, roofs, floors and partitions.Glass wool insulation →Fibrous insulation spun from melted sand and recycled glass, supplied mainly as light compressible rolls and batts for lofts, timber frames, floors and partitions.Expanded polystyrene →Rigid insulation moulded from steam expanded polystyrene beads and cut into boards, used in external wall systems, floors, cavities, formwork and below ground work.Extruded polystyrene →Rigid closed cell polystyrene board formed by extrusion, with a smooth skin and profiled edges, used in loaded and moisture exposed positions after professional review.Polyisocyanurate board →Rigid faced foam board formed by reacting isocyanate with polyol, produced continuously between bonded facings and used in roofs, walls, floors and insulated linings.Phenolic foam board →Rigid closed cell board made from a foamed phenolic resin with bonded facings, raised where a slim rigid insulation layer is wanted in walls, roofs and internal linings.Cellulose insulation →Loose fibre insulation made from recycled paper with mineral additives, installed by machine as a blown loft layer, a dense packed cavity fill or a damp sprayed application.Sheep wool insulation →Resilient batt and roll insulation made from scoured sheep wool, usually blended with a binder fibre, fitted between studs, joists and rafters in timber construction.Wood fibre insulation →Insulation made from defibred wood, supplied as flexible batts and as rigid boards, including profiled grades intended to be built into sheathing and sarking positions.Spray foam insulation →Two part polyurethane foam mixed at a spray gun and applied in place, where it expands and cures bonded to the surfaces it lands on, in open cell and closed cell forms.Multifoil insulation →Thin flexible roll built from reflective metallised films interleaved with wadding or foam layers, raised where the depth available for insulation is tightly constrained.Aerogel insulation →Insulation built around silica aerogel, most often a thin flexible blanket of aerogel held in a fibre carrier, used selectively at details where almost no depth is available.Hemp fibre insulation →Flexible batt and roll insulation made from the bast fibre of the hemp plant, usually blended with a binder fibre and mineral additives, for stud, rafter and joist positions.External wall insulation →A layered system fixed to the outside of a wall, combining an insulation layer, a reinforced base coat and a finish, together with the beads, trims and reworked opening details it needs.

Browse by role

By the role the material plays

The same entries, clustered by what they typically do in an assembly. A material can appear in more than one cluster because it genuinely plays more than one role.

Substrate and base

Backgrounds and bases that other materials are fixed or applied to.

External surface

The visible outer face of a wall or roof.

Where they appear

Parts of a building this category touches

An orientation aid only — it does not imply that any entry is suitable for that part of a particular building.

  • Foundations and groundworks · 2
  • External walls · 14
  • Roofs · 11
  • Internal walls and ceilings · 11
  • Floors · 12

Elsewhere on Build Design Hub

Planning guidance for this subject

This library explains what materials are. These sections help with choosing between them and preparing for the conversation.

Exterior materials guides →Planning guidance for the external envelope.Building envelope checklists →Preparation before envelope conversations.Renovation guides →How upgrade and retrofit work is planned.

Materials & Systems Encyclopedia

Reference entries for building materials, product formats and system components — what they are, what their behaviour depends on and what to ask about them.

Browse the full Materials Library →