A clear budget starts with clear scope.
The cost follows from the existing building and the agreed work.

Compare the complete intervention
Compare the glazing, rooflight and terrace reinstatement together in the budget. If a cheaper door system requires a different floor build-up, include that consequence in the same comparison.
Which trade-off matters?
A wide garden opening takes away wall space for cupboards. Compare a fully glazed rear wall with a smaller opening and a targeted rooflight, looking at both from the same seat.
What belongs in the budget?
- Survey, investigations and design preparation.
- Demolition, foundations, structure and new building elements.
- Electrical, water, heating and ventilation work.
- Windows, floors, walls, kitchens and bathrooms.
- Access, protection, scaffolding and waste removal.
- Clearly identified provisional sums and change arrangements.
A starting price needs a defined scope.
Ask for work, materials, VAT, assumptions and provisional sums to be clearly described. Undecided items should remain visible so an early estimate is not mistaken for a fully developed final budget.
Compare the content
Consider preparation, protection, timing and reinstatement alongside the total price.
Read the quote comparison guide