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Text Lesson 2 of 3

Thermal Performance

Understand R-value and thermal performance concepts.

20 minExternal Walls Compliance
Diagram for Thermal Performance
External Walls Compliance Thermal Performance
How to use the diagram Read the visual first, then connect each label to the lesson text and your calculator inputs. The aim is to make every assumption visible before you calculate.

Learning Objective

Connect wall build-up to thermal performance evidence.

Whole assembly thinking

Wall performance depends on the complete build-up, including insulation continuity and thermal bridges.

Lightweight risks

Lightweight walls often need closer attention to insulation and declared product performance.

Practice Task

  • Build a wall layer schedule.
  • Flag penetrations or discontinuities.

Calculator Tip

Use tested or manufacturer-supported values wherever possible.

Worked Example: Wall Build-Up Review

Scenario

A project uses cavity masonry on most elevations and lightweight framed walling at a feature bay.

Calculator Entry

Enter separate wall assemblies where construction differs materially.

Step-by-step method
  1. 1Group walls by assembly rather than by elevation only.
  2. 2List layers, insulation and thermal bridge risks for each group.
  3. 3Check that drawings and specifications describe the same assemblies.
  4. 4Keep evidence for each wall type in the report pack.
Expected conclusion

Different wall systems need separate evidence so the report stays reviewable.

Common Mistakes

  • Reporting a wall value without listing the complete wall build-up.
  • Missing thermal bridges, lightweight framing or insulation discontinuity.
  • Letting drawings, specifications and compliance notes describe different assemblies.

Quick Knowledge Check

1. What should you confirm before applying this lesson to a project?

Layers are listed.

2. Which piece of evidence should support the main input in this lesson?

Build a wall layer schedule.

3. What is the safest action if the information is incomplete?

Flag the missing evidence, use a conservative assumption where appropriate, and avoid claiming compliance until the information is confirmed.

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