What to discuss
Explain how you use the space below the roof and whether the covering is also due for renewal. This helps compare work from inside and outside. Specify the insulation material, thickness and intended thermal resistance, along with connections to the existing layers.
Agree what is included
A clear proposal distinguishes what stays, what is removed and what is newly installed. Ask which connections and finishes are included and which findings remain uncertain. Record changes and their price before giving approval.
What affects the price?
Compare the same roof sections and tasks before comparing prices. The total should explain materials, preparation, removal, access equipment and finishes, with clear exclusions and a process for approving additional work.
Preparing the work
Take photographs only from a safe place. Do not climb onto the roof yourself.
Tell us about your roof
Give the address, affected roof section and when the problem occurs or what you want to improve.
Inspection and proposal
Agree the inspection and its fees, then review materials, tasks, costs and any open questions.
Agree the work and access
After approval, arrange access and scheduling. Changes and additional work are discussed before proceeding.
Completion and maintenance
Review the completed work, keep the documents and agree how to report concerns and arrange maintenance.
Examples: insulation thickness in centimetres
| Selected λ (W/m·K) | Rd 3.5 | Rd 4.5 | Rd 6.0 |
|---|---|---|---|
| 0.022 | 8 cm | 10 cm | 14 cm |
| 0.035 | 13 cm | 16 cm | 21 cm |
| 0.040 | 14 cm | 18 cm | 24 cm |
Insulation materials and checks
| Material | Application | What to check |
|---|---|---|
| PIR / PUR boards | Rigid boards in a compatible roof build-up | Declared Rd, facings, joints and fire performance |
| Glass wool / stone wool | Rolls or boards; product depends on application | Avoid gaps and compression; roof boards need suitable load performance |
| EPS | Lightweight foam boards | Compressive strength, temperature and compatibility |
| XPS | Including suitable inverted roofs | Water exposure, drainage and system design |
| Wood fibre | Flexible or rigid products | Moisture behaviour, weight and suitability |
| Cellulose | Blown into suitable enclosed cavities | Fill density, settlement and airtight enclosure |
| Flax, hemp, cork and sheep wool | Product-specific bio-based options | Lambda, additives, moisture and fire behaviour |
| Cellular glass | Specific load-bearing insulation systems | Complete system and installation |
| Vacuum panels and aerogel | Specialist solutions for restricted space | Detail design, protection and product limits |