Common Mistakes in Commercial Area Measurement

An inaccurate lettable area figure doesn't just sit quietly in a lease document, it flows into rent, outgoings and valuations, and eventually someone notices the mismatch. Here are the mistakes that cause it.

1. Relying on Old Plans Instead of Re-Measuring

Buildings change. Tenancies get subdivided, walls move, fitouts alter the internal layout. A plan from ten years ago, even if it was accurate then, may not reflect what's actually on site today. Relying on old documentation instead of an on-site re-measurement is the single most common source of error.

2. Applying the Wrong Methodology

NLA, GLA and GLA-Retail are calculated differently, measured to different boundaries, and include or exclude different areas. Using NLA's internal-surface measurement approach on an industrial building that should be measured to external walls (GLA) will produce a figure that doesn't match what the methodology actually requires.

3. Inconsistent Treatment of Shared Areas

Whether a storage room, alcove, or recessed entry counts toward lettable area often depends on the specific building or centre's leasing rules, on top of the base PCA methodology. Measuring one tenancy under one interpretation and another tenancy under a different one creates inconsistency that surfaces the moment tenants compare notes.

4. Not Accounting for Structural Elements Correctly

Columns, piers and structural elements are treated specifically under the PCA methodology, generally excluded from NLA. Measurements that don't correctly exclude (or include, depending on the area type) these elements produce a figure that's off, sometimes by a meaningful margin in buildings with a lot of structure.

5. Measuring Once and Never Checking Again

Area figures get treated as fixed once they're in a lease, but tenancies change, through fitout works, subdivision, or reconfiguration, without anyone updating the measurement. A rent review or renewal is a natural point to confirm the figure still matches reality, but it's often skipped.

What an Accurate Process Actually Looks Like

• On-site measurement, not reliance on old documentation
• The correct methodology (NLA, GLA or GLA-R) confirmed and applied for the specific asset type
• Consistent treatment of shared and structural areas across every tenancy in a building
• A clear area schedule and floor plan that can be checked and understood, not just a single number

How Arya Designs Can Help

We measure on site every time, confirm the correct methodology before we start, and apply it consistently across every tenancy in a building. See our Commercial Building Measurement service.

Ready to Get Started?

If you suspect an existing area figure might be out of date or inconsistent, send us the details and we'll provide a fixed quote for an accurate re-measurement.