Why two rooms the same size can cost very different amounts
Floor area affects the structure, insulation, roof, cladding and internal finish, but it is only one part of the cost. A simple office with modest glazing and straightforward access is a different project from a room of the same size with bifolds, a fitted bar, media wall, canopy and extensive decking.
The ground can also change the construction method and labour requirement before the walls even start. A responsible quotation should reflect the actual plot rather than assume every garden is flat, dry and easy to reach.
The main cost drivers to put on your list
When comparing quotes, make sure you are comparing scope rather than the total on the last page. Items that are included as standard by one contractor can be optional extras with another.
- Overall footprint and height
- Foundations and groundworks
- Doors, windows and glazing area
- Cladding and external detailing
- Electrical installation and lighting
- Heating, cooling and connectivity
- Plastering, flooring and decoration
- Decking, canopies and landscaping interfaces
- Bespoke bars, media walls and joinery
- Access and materials handling
A realistic budget starts with priorities
If there is a ceiling you do not want to exceed, it is useful to say so. It lets the design focus on the features you will notice every day rather than spending money on details that do not improve the way the room works.
For some people the priority is a large bifold opening. For others it is acoustic separation, a high-quality bar or a better heating and cooling setup. Bespoke design should help move money towards the things that matter.
Ask for a defined quotation
A useful quote should tell you what construction, finishes and services are included, what assumptions have been made about the site and what is excluded. That is much more valuable than a low 'from' price that leaves the important choices unresolved.