Adjustments in ITZA Valuations: When and How to Apply Them
Why Adjustments Exist
The ITZA method assumes a "standard" retail unit: regular shape, adequate frontage, normal depth, good access, and a typical lease. In reality, no property is perfectly standard. Adjustments are percentage-based modifications applied to the zone rent to account for factors that make a property more or less valuable than the standard model predicts.
Getting adjustments right is often where the real skill in ITZA valuation lies. The zone calculations are mechanical — anyone can divide an area by a factor. But deciding whether a property warrants a -10% shape adjustment or a -15% one requires professional judgement and knowledge of how similar adjustments have been applied in comparable cases.
How Adjustments Are Applied
Adjustments are expressed as a percentage of the zone rent — either positive (adding value) or negative (reducing value). They can be applied to a specific zone or to the whole ground floor.
Adjustment Amount = Zone Rent × Adjustment Percentage
For example, a -10% shape adjustment on a whole floor rent of £80,000 would reduce the rent by £8,000. Multiple adjustments are applied independently and their effects are summed — they are not compounded.
Adjustments are only applied in Annual Rent mode — when you know the Zone A rate and are calculating the rent. In Zone A Rate mode (where you know the rent and are deriving the rate), adjustments are implicit in the comparable evidence already.
The Six Standard Adjustments
Shape
Irregular floor plans — L-shapes, T-shapes, tapering units, units with columns or step-backs — reduce the usable display and trading area compared to a rectangular unit of the same size. The more irregular the shape, the larger the negative adjustment.
| Characteristic | Typical Range |
|---|---|
| Minor irregularity (small step-back or single column) | -2.5% to -5% |
| Moderate irregularity (L-shape or significant narrowing) | -5% to -10% |
| Severe irregularity (T-shape, multiple changes in width) | -10% to -20% |
Shape adjustments usually apply to the whole floor, since the irregularity affects the overall trading experience.
Position in Pitch
A property's position within the high street or retail area affects its trading potential. "Pitch" refers to the relative desirability of different parts of the same street or centre.
| Position | Typical Range |
|---|---|
| Off-prime (slightly away from the core) | -5% to -10% |
| Secondary (noticeably outside the prime area) | -10% to -25% |
| Tertiary (fringe location) | -25% to -50% |
| Corner position with dual frontage | +5% to +10% |
| Next to anchor tenant or transport hub | +2.5% to +7.5% |
Note: Position is often already reflected in the Zone A rate if you're using location-specific comparables. Only apply a position adjustment if the Zone A rate you're using is for the broader area and doesn't already account for the specific pitch.
Frontage
Frontage width directly affects visibility and the ability to create an attractive window display. Narrow frontage is a disadvantage; unusually wide frontage for the depth can be an advantage.
| Characteristic | Typical Range |
|---|---|
| Very narrow frontage (under 12ft / 3.6m) | -5% to -15% |
| Narrow frontage (12–15ft / 3.6–4.5m) | -2.5% to -5% |
| Wide frontage (over 30ft / 9m for a single unit) | +2.5% to +5% |
| Return frontage (corner unit) | +5% to +10% |
Frontage adjustments typically apply to Zone A only, since that is the zone most directly affected by the shop window.
Depth
While the halving-back convention already accounts for depth (each zone is worth less), unusually deep units may warrant an additional adjustment because the rear space is difficult to use effectively. Conversely, shallow units with no depth beyond Zone A can sometimes attract a small positive adjustment for their efficient layout.
| Characteristic | Typical Range |
|---|---|
| Excessively deep (over 80ft / 24m) | -5% to -10% on rear zones |
| Very deep with poor natural light at rear | -10% to -15% on rear zones |
| Shallow, efficient layout (Zone A only) | +2.5% to +5% |
Quantum
Very large units may attract a discount because fewer tenants can afford the total rent, reducing demand. Conversely, very small units in prime locations can command a premium because they offer affordable access to a high-value pitch.
| Characteristic | Typical Range |
|---|---|
| Very large unit (over 5,000 sq ft) | -5% to -15% |
| Large unit (3,000–5,000 sq ft) | -2.5% to -5% |
| Very small unit in prime pitch (under 500 sq ft) | +5% to +10% |
Lease Terms
The standard ITZA valuation assumes a typical institutional lease. Where the actual lease terms differ materially, adjustments may be appropriate:
| Characteristic | Typical Range |
|---|---|
| Short lease (under 5 years) | -5% to -10% |
| Onerous repairing obligations (full repairing and insuring on old building) | -2.5% to -5% |
| Restrictive user clause | -2.5% to -10% |
| Break clause in tenant's favour | +2.5% to +5% |
Note: In rent review valuations, the adjustment is based on the hypothetical lease terms specified in the rent review clause, not necessarily the actual lease terms.
Combining Multiple Adjustments
It's common for a property to require several adjustments. For example, an L-shaped unit on a secondary pitch with narrow frontage might have:
- Shape: -10% on whole floor
- Position: -15% on whole floor
- Frontage: -5% on Zone A
Each adjustment is calculated independently against the relevant zone rent, and the total adjustment is the sum of all individual amounts. Be careful not to "double-count" — if a property's irregular shape is already the reason it's in a secondary pitch, applying large adjustments for both shape and position may overstate the discount.
When Not to Adjust
Not every property needs adjustments. If your comparable evidence comes from genuinely similar properties — same pitch, similar size, similar configuration — the Zone A rate derived from those comparables already reflects the property's characteristics. Adjustments are most important when:
- Your comparables are from a different pitch or position
- The subject property has unusual physical characteristics
- There is limited comparable evidence and you need to adjust from a broader area
Apply Adjustments in the Calculator
Our free ITZA Calculator supports unlimited adjustments in Annual Rent mode. Add adjustments for any reason, apply them to individual zones or the whole floor, and see the effect on the total rent instantly.