Introduction
A home extension is exciting, but poor planning leads to delays, cost overruns and frustration.
Before building begins, key decisions must be locked in.
Here’s your essential checklist.
1. Purpose of the Extension
- Kitchen-diner?
- Home office?
- Additional bedroom?
- Open-plan living?
Clarity here drives layout decisions.
2. Budget (With Contingency)
Set:
- Build cost
- Design fees
- Structural engineering
- Planning fees
- 10–15% contingency
Under-budgeting is the #1 mistake.
3. Planning Permission or Permitted Development?
Check:
- Local authority rules
- Neighbour proximity
- Property type restrictions
4. Structural Considerations
Will you need:
- Steel beams (RSJs)?
- Load-bearing wall removal?
- New foundations?
Structural engineering input is essential early on.
5. Utilities and Services
- Boiler capacity
- Drainage runs
- Electrical upgrades
- Underfloor heating
6. Access During Construction
How will:
- Materials enter?
- Waste exit?
- Security be maintained?
7. Timeline
Agree:
- Start date
- Milestones
- Completion estimate
Conclusion
The more detailed your pre-build planning, the smoother the project.
An extension should add:
- Space
- Value
- Flow
Not stress.