Planning Constraints That Kill Schemes—And Why You Need to Know Early

Here's a scenario you've probably lived:

Developer brings a scheme to you. Viability looks tight but workable. 5% edge on cost, good timing assumptions. You move forward.

Three months in, a restrictive covenant surfaces. Or a conservation area constraint you didn't factor in properly. Or an access arrangement that's harder than expected.

Suddenly, the scheme changes. Costs go up 8-10%. Timeline extends 4-6 months. That 5% edge is gone. The whole deal pivots or dies.

Cost to find that out? Three months of development team time, legal costs, extended marketing. Anywhere from £50k to £200k depending on the stage.

Could have been caught day one. If you'd known what to look for.

The Gap

Here's the problem: planning constraints aren't in one place.

Some are obvious (conservation area status, listed building, Article 4 directive). Most teams get those in outline search.

But others hide in policy documents, historic planning decisions, S106 agreements, and local plan policy detail that most developers don't read closely. And they're the ones that kill deals.

Examples From the Real World

Case 1: The Heritage Impact Developer sees "conservation area—minor constraint, visual assessment needed." What they didn't catch: the authority's heritage impact policy has a requirement for matching materials to Victorian-era buildings within 50m. All pre-cast concrete now needs bespoke cladding. Cost impact: £80k per unit. Deal dies.

Case 2: The S106 Trap Viability assumes 15% S106 requirement based on local plan. What nobody noticed until 6 months in: the last permission in the area included a £2m sports facility contribution as precedent. The authority's now expecting a higher negotiated position. Adjusted requirement: 22%. Development becomes unviable.

Case 3: The Restrictive Covenant Nobody asked the seller about old covenants affecting the land. Surfaces in legal. Requires insurance (if insurable at all) or discharge via indemnity. Cost: £15k-£40k depending on authority willingness to release. Timeline: 6-8 weeks. Suddenly your contractor can't start on schedule.

All of these are discoverable. None of them should be surprises past initial scoping.

What Proper Constraint Analysis Does

If you front-load planning constraint analysis, you:

1. **Identify policy-driven costs early** - Understand what the local authority actually expects (not what policy says on paper) based on recent decisions and S106 history.

1. **Spot restrictive covenants and access issues** - Before you're committed, before you've gone through legal's full review, before you've signed conditional contracts.

1. **Test scheme assumptions against reality** - Density assumptions, parking policy, affordable housing requirements—all validated against local authority practice, not just policy text.

1. **Build time for negotiations** - If discharge of covenant or policy exception is needed, you identify it with months to work through it, not weeks to panic.

All of this costs less to do upfront than to discover halfway through.

Why This Matters Now

Domus's planning automation is coming soon. But even today—with current tools—you should be doing more systematic constraint analysis before committing to schemes.

Read the local plan policies that actually affect your scheme. Check recent decisions by the authority in the area. Ask about covenants and easements. Get conservation area guidance if applicable.

Take a day on constraint mapping before you commit months to development.

That discipline alone will change your deal flow.