Fencalc XA2021
Measure consistently
Projection and height must be taken from the correct points on the opening and shading feature. Inconsistent measurement can change the result.
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
Decide whether an overhang should be treated as compliant shading.
Side extension
A shading feature should cover the opening adequately, including side extension where relevant.
Practice Task
- Sketch one overhang.
- Record projection, height and side extension.
Calculator Tip
Keep the sketch with the project report.
Worked Example: Overhang Check
Scenario
A north-facing window has height relationship H = 900 mm. The proposed overhang projects P = 600 mm from the wall face.
Calculator Entry
Enter the shading method, projection and height relationship only if the drawing evidence supports it.
Step-by-step method
- 1Confirm the shading is external and fixed.
- 2Measure H and P from consistent points on the section.
- 3Apply the required multiplier for the project context.
- 4Record whether P is deep enough and whether side coverage is adequate.
Expected conclusion
If the overhang cannot be measured or justified, treat the opening as unshaded until confirmed.
Common Mistakes
- Claiming shading that is not external, permanent or measurable.
- Measuring projection and height from inconsistent points on the opening.
- Counting uncertain future screens or occupant-controlled items as compliant shading.
Quick Knowledge Check
1. What should you confirm before applying this lesson to a project?
Projection is recorded.
2. Which piece of evidence should support the main input in this lesson?
Sketch one overhang.
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.