There is no single insulation material that suits every home. Start with the part of the building you want to improve, how it is built and the problem you want to solve. Then compare complete installation proposals.
A cheap product can still be an unsuitable choice for the job. Equally, an expensive material does not prove that the design or installation will be right.
Identify what is being insulated
Ask the installer to describe the existing construction and the proposed location of the insulation.
- Loft floor or roof: insulating an unused loft floor is a different job from insulating roof slopes around a living space. Flat roofs also need a suitable design. Energy Saving Trust's roof guide explains these distinctions.
- Walls: cavity walls and solid walls need different approaches. Solid-wall insulation may be fitted internally or externally; those options have different effects on rooms, finishes and the outside of the building. See the solid-wall insulation guide.
- Floors: a suspended timber floor differs from a solid floor. The floor construction and access affect the work needed. See the floor insulation guide.
Do not choose a system from the property's age alone. Ask what has been established about this building and what still needs checking.
Compare the material as part of a system
Rolls, boards and other insulation products are installed in different ways. The material name is only one part of the specification.
Ask for the product, thickness and proposed layers in writing. The installer should explain why these suit the location and existing construction. Also ask how corners, gaps, edges and openings will be handled, and what finishing work is included.
For example, two internal-wall quotes may cover different rooms, finishing work or alterations. Comparing their totals without checking those differences will not tell you which offers better value.
Ask about moisture and ventilation
Insulation changes how a building loses heat. The design also needs to consider moisture and ventilation. Existing damp or leaks deserve attention before work is specified.
Traditional construction may need a different approach from a modern wall. Use Historic England's guidance for older homes to prepare questions, then obtain advice for the actual building. Terms such as "natural" or "breathable" do not, by themselves, establish that a complete system will be suitable.
Ask the designer to explain how the proposal addresses the building's moisture behaviour, ventilation and relevant fire requirements. A sales description of the material is not an answer to those design questions.
What should a comparable quote include?
Send the same brief to each installer. Ask each to identify:
- The rooms or areas covered, and the construction they have identified.
- The specified materials and thicknesses.
- Preparation, installation, finishing and waste removal.
- Any ventilation changes or associated work.
- Relevant permissions and who will check whether they are needed.
- Exclusions, warranties and the person responsible for the design and installation.
If an item is missing, ask about it before comparing prices. A supply-only price is different from a proposal that includes preparation and making good.
Use your EPC to prepare questions
An EPC may recommend insulation, but it does not provide a detailed specification for every part of the building. Read what your EPC can tell you and take the certificate to your adviser.
A useful question is: "Which recommendation addresses my concern, and what needs checking before you can specify it?" That keeps the discussion connected to the home rather than a product brochure.
For the wider decision, read about the benefits and limits of energy-efficiency improvements. If you need an EPC for a London home, check the property price.
Sources checked: 22 October 2026. Material selection and installation design require advice suited to the building.