Compare the four approaches
| Type | Main change | First question to ask |
|---|---|---|
| Rooflight | Uses the existing roof volume, with windows in the roof slope | Is there enough usable height after the floor and insulation are built? |
| Dormer | Projects out from a roof slope | Where would the extra standing space improve the room? |
| Hip-to-gable | Changes a sloping roof end to a vertical gable | Does the existing roof have a hip that can be altered? |
| Mansard | Substantially reshapes a roof slope | Is this level of roof alteration appropriate for the property? |
Start with a room, not a roof shape
Describe how you expect to use the space. A desk needs a comfortable place to sit and move around; a bedroom needs a sensible bed position and storage; a bathroom brings plumbing and ventilation into the brief. Sketch where furniture might go before becoming attached to one conversion type.
Ask for a section drawing as well as a floor plan. A floor outline alone can make low areas beneath a sloping ceiling look more useful than they are.
Consider the rooms below
The new staircase may affect a room or landing below. Ask how the proposed layout changes circulation, doors and storage on the existing floors. Check how the new layout affects the rooms you already use.
Your next decision
- Choose a preferred use and one alternative.
- Gather existing drawings if you have them.
- List the parts of the house you do not want to compromise.
- Request an assessment before relying on a particular conversion type.
Sources & review
Published by Coalesce Local Ltd. Reviewed 18 September 2026.