🏠 Buying & Renovating
Loft Conversions: What to Check Before You Start
Head height, stairs, and structure decide whether a loft conversion is straightforward, expensive, or impossible.
Dana Whitlock · Sep 24, 2026 · 8 min read · 5 steps
A loft conversion can add a bedroom and bathroom without losing garden space, and it is one of the most popular ways to gain room in a house.
But not every loft is suitable, and the costs vary widely depending on the roof structure.
Measure the head height
Measure from the top of a ceiling joist to the underside of the ridge beam. As a rough guide, around 2.2 metres or more makes a conversion much easier. Below that, you may need to lower ceilings below or raise the roof, both of which add cost and complexity.
Types of conversion
The right type depends on your roof shape, budget, and local planning rules.
- Rooflight (Velux) — the cheapest; adds windows without changing the roof shape
- Dormer — a box extension that adds headroom and floor space
- Hip-to-gable — extends a sloping side roof up to a vertical wall
- Mansard — reshapes one slope almost vertical; the most space and the most cost
Stairs and fire safety
You will need a proper staircase, which takes space from the floor below. Building regulations also require a protected escape route, which can mean fire doors, mains-linked smoke alarms, and sometimes changes to the hallway. Plan the staircase position early — it often decides the whole layout.
Permissions and neighbours
Many simpler conversions fall under permitted development, but rules vary by area and property type, and conservation areas and flats have stricter controls. If you share a wall with a neighbour, party-wall rules may apply. Building-regulation approval is needed regardless.
Choosing a builder
Look for firms that specialise in lofts, ask to see finished projects, and get a fixed-price quote that lists structural steel, insulation, electrics, plumbing, and making good. See our guide to hiring a contractor for the paperwork to ask for.
This is general home-maintenance information, not professional advice. Building codes, permits, and safe practices vary by location — consult a licensed contractor, electrician, or plumber for work beyond your experience.