Discuss insulation together with the existing roof assembly, moisture questions and junctions. A thickness or product name is not yet a suitable design. Keep technical assessment, desired improvement and any subsidy conditions identifiable as separate decisions.
Why does the question start with existing layers?
First establish which construction and layers are present. Drawings may help, but they need to correspond to the actual roof. Has insulation previously been added internally, is insulation already present externally, or is the assembly unknown? These differences should not disappear behind one general line for additional roof insulation.
Ask how the proposed change relates to those starting points. Moisture behaviour and connections to adjoining building components also deserve attention. This website does not prescribe a layer sequence for your property. A suitable proposal should identify known information, the assessment still needed and the basis on which the solution will eventually be selected.
Which details can change when height is added?
Additional build-up height can change the relationship with edges, outlets, rooflights and doors. Do not therefore assess only the central roof plane. A junction that worked with the existing assembly is not automatically appropriate for an altered situation.
Ask for an overview of components that will change alongside the insulation and those intended to remain. This prevents an apparently simple insulation choice from unexpectedly raising an additional edge or facade question later. The desired improvement should be discussed together with those consequences. A proposal listing only a material surface area gives insufficient visibility of the complete work boundary and the interfaces requiring coordination.
How can subsidy conditions be separated from technical suitability?
A possible subsidy does not establish that a particular assembly suits your roof. Check any current conditions with RVO and retain technical assessment as a separate step. This guide gives no amounts, surface-area thresholds or material values on which to base an application.
Ask beforehand which documentation will accompany the chosen measure, including a clear description of completed work and relevant product information. Then check whether it meets the requirements of the scheme you intend to use. Conditions can change and depend on the situation. A general roofing website should not replace that check with an automatic promise of eligibility or treat a grant as technical approval.
What should be recorded before execution?
Record which roof areas will be improved, which existing layers retained and which junctions included in the instruction. Identify who assesses the construction relationships and how unknown components will be handled during preparation. Material selection belongs within that reasoning, not apart from it.
Keep the documentation requirements alongside the proposal as well. Gathering missing information afterwards may be harder once layers are concealed. Clear preparation makes the handover traceable without inventing a performance guarantee. The local planner can record your interest in insulation as a consideration, but it does not calculate heat loss, financial payback or eligibility for a funding programme.
Worth asking
Frequently asked questions
Does this planner calculate insulation values?
No. It collects project questions and performs no building-physics calculation.
Does subsidy eligibility prove suitability?
No. Technical assessment and scheme conditions are different questions. Check them separately.
Must the roof edges always change?
Not automatically. Have available space and the selected assembly assessed before deciding what stays or changes.