PIR insulation
Changing insulation after signing the contract: what should the variation record?
At a glance
A supplier cannot deliver the specified board and offers another of the same thickness. Record precisely what would change: just the manufacturer, the facing, the board format or the way the layer is installed. Without that detail, one party may expect an equivalent material while another has priced a cheaper assembly with different accessories. Here is a practical way to compare the two proposals and record a decision before delivery. It is especially useful when the client buys the material and a separate contractor installs it.
Identify the original item
Give the room or roof slope, drawing number and estimate revision. “Change the insulation in the house” is too broad.
Enter the original product designation and the adjacent layers. If the documents specify performance for the whole assembly, keep that requirement with the item. A thickness in millimetres does not fully describe the work.
List the differences side by side
Compare exact variants in two columns. Check the declared thermal resistance at the offered thickness and the board edges, dimensions and facings relevant to installation. Attach documentation for each proposal.
Mark a missing entry as “to be confirmed” and name the person who will obtain it. A blank load or adhesive entry does not mean the products perform alike.
Who checks suitability for this location?
The installer can assess changes to the work on site. Have the designer review changes affecting the design assumptions. The supplier can provide board data, but a quote does not establish the effect on a complete roof or floor.
Record each answer against the specific question. Acceptance of a board beneath the garage screed does not extend to façade insulation merely because the same brand supplies both.
Include consequential work
A different format changes the board count and cuts. Request a revised cutting layout where there are many corners and clarify who pays for unused packs. Compare totals for the same work area.
If the substitute requires different fixings, an intermediate layer or substrate preparation, include materials and labour. A cheaper board may not reduce the bill for the completed stage.
Define where the change starts
If work has started, mark the boundary between the two products on plan and agree the joint detail. Different edge profiles need not fit like two boards of the same type.
Account for unopened packs from the original order. Returning them, keeping spares or using them elsewhere are separate decisions that affect the amount of new material needed.
Close out the variation
Attach dated documents, price, scope and timing. Keep the product description as well as any shop link: an updated product range may put a different revision at the same address.
After installation, compare the actual changeover line with the drawing. A label photo from the new batch and its installation location will help the owner identify compatible materials for a future repair.
7 branches. Materials closer to your project.
