5 Fenestration Mistakes to Avoid

Glazing calculations are often the most complex part of a SANS 10400-XA compliance report. Based on our review of hundreds of submissions, here are the top 5 mistakes professionals make when assessing fenestration.

1. Using Glass-Only Values

Many people mistakenly use the U-value and SHGC of the glass pane itself. SANS 10400-XA requires the whole-window value, which includes the framing material. Aluminum frames conduct heat much faster than uPVC or timber, significantly changing the overall performance.

2. Incorrect Orientation Sectors

Labelling rooms by name (e.g., "Bedroom 1") instead of using the outward-facing facade direction is a common error. Always use an outward arrow perpendicular to the external facade to assign it to the correct orientation sector (N, S, E, or W).

3. Calculating Glazing Percentage Wrong

Glazing percentage must be calculated per storey, not across the entire building all at once. A highly glazed ground floor might fail even if the upper floor has very few windows.

4. Claiming Unverifiable Shading

To claim shading benefits, the overhang or shading device must be external, permanent, and measurable. You cannot claim shading for internal blinds, trees, or future planned screens that aren't on the working drawings.

5. Missing Product Evidence

Submitting results that cannot be traced back to drawings or product data is an immediate red flag. A pass result in Fencalc is only useful if the evidence pack supports it. Ensure every window specified matches a real product data sheet.