What does a specifier check before selecting an insulation product?
They check the declared thermal conductivity, the fire classification under the standard their project uses, and the thickness needed to reach the required performance. Fire classification has become the first filter on most projects rather than a later detail.
A building services engineer is selecting insulation for a project where the fire specification will be audited.
Reviewed 4 August 2026
Scope and specifications
- Product type and base material
- Mineral wool, foam, cellular glass and aerogel behave differently in fire and moisture.
- Declared thermal conductivity
- The number every calculation starts from.
- Fire classification
- Increasingly the first filter, not a secondary property.
- Thickness range and dimensions
- Determines whether the required performance fits the space.
- Compressive strength
- Decides suitability under load.
- Water vapour and moisture behaviour
- Governs performance in service and condensation risk.
- Service temperature range
- Critical for industrial and process insulation.
Documents buyers may need
| Document | What it proves | Where it belongs |
|---|---|---|
| Declaration of Performance or equivalentAsked at: specification and approval | The regulated statement of the product's declared properties | Publish it |
| Fire classification test reportAsked at: first filter on most projects | Reaction to fire under the standard the project requires | Publish it |
| Thermal conductivity test reportAsked at: specification | Declared value measured under a named method | Publish it |
| Technical datasheetAsked at: first evaluation | All declared properties, thicknesses and application limits | Publish it |
| Environmental Product DeclarationAsked at: green-rated projects | Life-cycle data, requested on rated projects | Publish it |
| Installation guidanceAsked at: before installation | How the declared performance is actually achieved on site | Publish it |
| Batch conformity certificateAsked at: delivery | That delivered material matches the type-tested product | Per shipment |
Details for a useful enquiry
- Application and element being insulated
- Roof, wall, floor and pipework are different products.
- Required performance value
- Determines the thickness and product.
- Fire requirement
- Frequently governs the whole selection.
- Quantity and project size
- Basis of price and supply planning.
- Project location
- Freight is significant for bulky products.
- Programme dates
- Insulation sits on the critical path more often than expected.
Questions suppliers ask
Should we publish a thickness-to-performance table?
Yes. It is the calculation every specifier does, and doing it for them in a clear table both saves them time and prevents the errors that get blamed on the product. It is also the page most likely to be found by someone searching for a performance value.
How should fire classification be presented?
As the classification under the standard, with the test report reference, for each product and thickness where it differs. It has become the deciding property on a large share of projects, and presenting it as a logo rather than a classification suggests the detail will not survive scrutiny.
Is installation guidance worth the effort to publish?
It is one of the highest-value pages an insulation manufacturer can have. Installed performance is where products lose their reputation, and detailed guidance protects the product, helps the contractor and gives the specifier confidence that the declared value is achievable.
Check which documents and standards your buyer needs; requirements vary by market, customer and contract.
Plact Research. Plact's editorial desk for buyer-evidence research. Industry standards, documents and buyer questions are researched and drafted with Plact's AI tools, then reviewed by Praveen Kavuri before publication. Every claim cites the standard, regulation or public source it rests on.
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