Most loft conversions do not need full planning permission, but the rules depend on your home and where you live. Here is the straight version, and we handle the whole process for you.
We tell you what your roof allows and give you a fixed price, in one visit.
Book your free survey Call free, 7 days 0800 028 0099For most houses in London and Kent, a loft conversion falls under permitted development, which means no full planning application is needed. That covers the majority of rear dormers, hip to gables and Velux conversions on ordinary houses.
You are more likely to need full permission if you live in a flat or maisonette, in a conservation area, in a listed building, or if the design goes beyond the permitted development limits, for example a large mansard or anything that changes the front roof slope.
Separately, and this catches people out, every loft conversion needs building regulations approval even when planning permission is not required. That covers structure, fire safety, insulation and the staircase.
All housing and community permission guidelines are different, so it is important to always check before going ahead. We can help with this after the design process.
Planning permission asks whether you are allowed to change the outside of the building. Building regulations ask whether what you have built is safe. They are different approvals from different departments, and the second one applies to every loft conversion without exception, including the ones that sail through under permitted development.
This is where most of the technical work on a conversion actually sits, and it is worth knowing what your builder is being held to.
The existing ceiling joists were never designed to carry a floor. New floor joists have to be sized and installed to take the load, usually spanning onto the supporting walls rather than resting on the old ceiling. Where a chimney breast or a wall is removed, steel is calculated and specified. This is why structural calculations get produced before anyone starts, not during.
Adding a habitable floor changes the fire strategy of the whole house, which surprises people. The staircase becomes a protected route, which usually means fire doors to the rooms opening onto it and interlinked smoke alarms on every floor. On a three-storey house the requirements step up again. It is the most common reason a conversion done cheaply fails sign-off.
There is no minimum ceiling height written into the regulations for a loft room itself, which is a common misunderstanding. What is fixed is the headroom over the staircase, and that is what usually decides where the stairs can go and how much of the room is genuinely usable. A survey measures this before any design work, because it constrains everything after it.
The new floor has to meet current thermal standards, which are considerably tighter than they were when most of these roofs were built. Ventilation matters just as much: a well-insulated loft with nowhere for moisture to go is how condensation problems start. Both get designed in rather than added at the end.
We handle the calculations, the drawings and the building control sign-off as part of the job, so you are not appointing a separate engineer or chasing an inspector yourself.
The starting point for most homeowners: when permission is needed and when it is not.
Read the guideThe rules that let most loft conversions go ahead without a full planning application.
Read the guide → DormersDormers are the most common London conversion, and the most common planning question.
Read the guide → By conversion typeHow the type of conversion you choose changes the planning route.
Read the guide → The 10-year ruleWhat the rule change means for older, unauthorised conversions.
Read the guide → The four-year ruleThe rule this replaced, and why it still comes up.
Read the guide → Getting startedPractical advice for getting your project off to the right start.
Read the guide →Many loft conversions are allowed under permitted development, which means no full planning application. But flats, maisonettes, homes in conservation areas, listed buildings and larger designs such as some mansards usually do need permission. We check exactly what applies to your property on the free survey.
Permitted development is a set of national rules that allow certain building work without a full planning application, within volume limits and design conditions. Most rear dormers on houses fall inside it. Flats are excluded, and conservation areas have tighter rules.
If your conversion involves work on a wall you share with a neighbour, which is common on terraces and semis, you must notify them under the Party Wall Act. It is a legal notice, not planning permission, and it protects both sides. We guide you through it as part of the project.
Yes, always, even when planning permission is not required. Building regulations cover the structure, fire safety, insulation, stairs and head height. We handle the structural calculations and the building control sign-off for you.
Conservation areas have tighter rules, particularly on anything visible from the street, and permitted development rights are often restricted. It does not mean you cannot convert, it means the design needs to be handled carefully. We advise on what will get through.
We do. Our in-house team prepares the drawings, submits any planning application and handles the structural calculations and building control, so you are not chasing an architect and a builder separately.
Book a free, no-obligation design visit. We will tell you what your roof allows, show you what it could look like, and give you a fixed price. No pressure, no jargon.
A short conversation about the house and what you are hoping to do. No sales pitch.
We measure up and tell you honestly what your roof allows, what it would look like, and what it involves.
Itemised, with no hidden extras, and a ten-year written guarantee on the finished work.
