Planning viability assessment software that holds up under scrutiny.
Planning viability is where deals are made or lost. Domus gives development teams the modelling, scenario testing, and evidence trail to support section 106 negotiations with numbers they can actually stand behind.
Book a demo to see the full platform
Where things go wrong
A planning viability case is only as strong as the model behind it.
Most viability problems aren't about the numbers being wrong. They're about teams presenting numbers they can't trace, can't stress-test on demand, and can't connect to a consistent scheme record.
Section 106 obligations negotiated without a tested residual land value model
Viability assessments submitted with assumptions the team can't defend under scrutiny
Sensitivity runs done in separate spreadsheets that don't connect back to the live scheme
Planning counsel working from a different version of the numbers than the development team
What a viability review looks like in Domus
Waterside Quarter, Leeds LS10 1EJ
BorderlineSaved 2 days ago · Leeds City Council
Policy baseline
- Affordable trigger
- Triggered (>10 units)
- Affordable %
- 30.0%
- Tenure split
- 70% SR / 30% AH
- CIL zone
- Zone B
- CIL rate
- £175/sqm
- CIL index linked
- Yes
- S106 assumption
- Standard obligations
- Density guidance
- 75–150 dph
Planning constraints
REVIEW- Green Belt
- Conservation Area
- SSSI / Ecology
- Flood Zone 2
- Listed Building proximity
Scheme compliance
- NDSS compliant
- Density in guidance
- Mix matches guidance
- Affordable meets policy
Build costs
- Quality band
- Standard
- Base cost
- £2,750/sqm
- Core build
- £8,320,000
- External works
- £416,000
- Contingency (5%)
- £437,000
- Professional fees
- £782,000
- Statutory costs (CIL/S106)
- £623,000
- Total dev cost (pre-finance)
- £10,840,000
Revenue & comparable evidence
- Pricing method
- Comparable sales
- Baseline PSM
- £4,100/sqm
- New build premium
- 3.5%
- Effective PSM
- £4,250/sqm
- Absorption rate
- 3.5 units/month
- Sell-out period
- 24 months
- Evidence confidence
- 78/100
- GDV
- £19,850,000
Decision verdict
BORDERLINEBreak-even thresholds
- Max affordable housing
- 22%
- Min GDV (base costs)
- £18,940,000
- Max build cost PSM
- £2,910/sqm
- Min profit on GDV
- 10.8%
Stress matrix
| Scenario | Profit on GDV | Verdict |
|---|---|---|
| Base case | 12.5% | Borderline |
| Costs +5% | 10.2% | Not viable |
| GDV -5% | 9.8% | Not viable |
| AH at 20% | 14.8% | Viable |
Representative data only. Every field is a real input or output in the Domus viability flow.
How Domus handles viability
From residual land value to planning submission, all in one place.
Residual land value modelling
Build the RLV case properly across GDV, costs, finance, contingencies, and developer return so the viability position is defensible from the start.
Scenario and sensitivity testing
Test how changes to affordable housing percentage, cost assumptions, or phasing affect the scheme's viability. Run scenarios without rebuilding the model each time.
Submission-ready outputs
Carry the tested viability position into formal reviews and planning submissions with a clear evidence trail, not a snapshot that can't be traced back to the working model.
Section 106 viability
What section 106 viability actually requires.
A section 106 viability assessment uses the residual land value method to demonstrate whether a scheme can viably deliver the affordable housing or other obligations a local authority requires. If the RLV with full obligations falls below the benchmark land value, the scheme is considered unviable and negotiations begin.
The model needs to hold together under challenge. That means consistent assumptions, a clear evidence trail, and the ability to run sensitivity analyses that show how the viability position changes under different scenarios.
That's exactly what Domus is built for: not a standalone calculator, but a live scheme record that connects the viability model to everything that happens next.
Common questions
Planning viability: frequently asked questions.
What is a planning viability assessment?+
A planning viability assessment is a formal appraisal that tests whether a development scheme can deliver required planning obligations such as affordable housing, section 106 contributions and CIL, and still generate a competitive return. It uses the residual land value method to demonstrate viability under proposed planning conditions.
How does section 106 viability work?+
Section 106 viability uses the residual land value method to determine whether a scheme can viably meet local authority obligations. If the residual land value with full s106 obligations falls below the benchmark land value, the scheme is considered unviable and obligations can be negotiated down.
What is a benchmark land value?+
A benchmark land value (BLV) is the minimum return a landowner needs to voluntarily release a site for development, typically existing use value plus a reasonable premium. It is compared against the residual land value to determine whether a scheme can viably support planning obligations.
What is CIL viability?+
Community Infrastructure Levy viability refers to demonstrating that a scheme remains financially viable after CIL charges are applied. Developers may seek exceptional circumstances relief if CIL makes a scheme unviable, using the same residual land value methodology as section 106 assessments.
How do you calculate affordable housing viability?+
Build a residual land value model at the proposed affordable housing percentage and test whether the RLV meets or exceeds the benchmark land value. If it falls short, the affordable housing requirement is considered unviable at that level and can be renegotiated with the local planning authority.
What software is used for planning viability assessments?+
Most viability assessments are built in bespoke spreadsheet models or dedicated development appraisal software. Domus connects the viability model directly to the live scheme record, enabling scenario testing, sensitivity analysis, and submission-ready outputs without maintaining separate spreadsheets.