The permitted development limits
Permitted development is a national set of rights that lets you extend a house without a planning application, as long as the work stays inside fixed limits. For roof extensions the Planning Portal lists them as follows.
- The new roof volume, including any earlier roof extensions, must not exceed 40 cubic metres on a terraced house or 50 cubic metres on any other house.
- Nothing may be higher than the highest part of the existing roof.
- On the main elevation, where it faces a road, the work must not extend beyond the existing roof slope. In practice: no front dormers.
- Materials must be similar in appearance to the existing house.
- No verandas, balconies or raised platforms.
- Side-facing windows must be obscure-glazed, and any opening part must be at least 1.7 metres above the floor.
- Except for a hip-to-gable enlargement, or one that joins the main roof to the roof of a rear or side extension, the original eaves must be kept and the work set back at least 20cm from them where practicable. Nothing may overhang the outer face of the wall.
- The house must not be on designated land, which includes conservation areas, and the rights apply to houses only, not to flats or maisonettes.
When you need a planning application
If any one of those limits is broken, you need full planning permission. The common reasons in Birmingham are a house in a conservation area, a design that goes over the volume allowance (which happens most often with L-shaped dormers on terraces), a dormer on the front slope, a mansard that rebuilds the roof profile, or a balcony on the dormer.
Permitted development rights can also be removed for a particular house: by an Article 4 direction across an area, or by a condition on the original planning permission, which is common on estates built in the last few decades. Your house's planning history, which the council holds, shows whether that has happened.
Rooflights are a separate case. They fall under a different class of permitted development and can usually be fitted if they project no more than 150mm from the slope and sit below the ridge, and that allowance is not removed just because a house is in a conservation area. An Article 4 direction can still remove it.
Birmingham's conservation areas and Article 4 directions
Birmingham City Council lists 29 conservation areas (page updated 2 June 2026). Inside any of them a roof extension needs planning permission. Eleven have Article 4 directions, which bring even minor changes, such as replacing windows or re-roofing, under planning control: Austin Village, Bournville Village, Edgbaston (part), Greenfield Road in Harborne, High Street in Sutton Coldfield, Moor Pool in Harborne, Moseley, Old Yardley, St Agnes in Moseley, Selly Park and Selly Park Avenues.
The other residential conservation areas include Anchorage Road and Four Oaks in Sutton Coldfield, Barnsley Road, Lee Crescent, Ryland Road and St Augustines in Edgbaston, Bournville Tenants, Harborne Old Village, Kings Norton, Northfield Old Village and School Road in Hall Green. The council publishes a boundary map and an appraisal for each one, and the appraisal is the best guide to what a successful design looks like there.
Estate consents: Bournville and Calthorpe
Two large Birmingham estates add their own layer. Homes inside the Bournville Estate Scheme of Management need the Bournville Village Trust's approval for alterations; at the time of writing the Trust says it processes major alterations within ten weeks. Parts of Edgbaston are covered by the Calthorpe Estate scheme of management, which sets out the rights and obligations of freeholders there. Neither replaces planning permission, and planning permission does not replace either of them.
Solihull is a different council
If you live in Solihull, Shirley, Olton or Knowle, your planning authority is Solihull Metropolitan Borough Council. The permitted development rules are the same national ones, but the conservation areas (20 of them, including Knowle and Olton) and any Article 4 directions are Solihull's, so check its maps rather than Birmingham's.
Get a Lawful Development Certificate
Permitted development needs no application, but it helps to have proof. A Lawful Development Certificate is a formal decision from the council that the proposed work is lawful without planning permission. It costs less than a planning application, it settles any doubt about the volume calculation before building starts, and buyers' solicitors often ask for it when you sell. We recommend one for every permitted development conversion.
Other permissions that are not planning
Building Regulations approval is needed for every loft conversion, with or without planning permission; our Building Regulations guide explains it. On a terrace or a semi, the Party Wall etc. Act 1996 usually applies, because beams and joists bear on the shared wall: you serve notice on the neighbours, normally at least two months before that work starts. And because bats are a protected species and often roost in roofs, a bat survey may be needed before the roof is opened if there are signs of them.
Questions people ask
Can I build a dormer without planning permission in Birmingham?
Yes, a rear dormer can be permitted development if the house is not in a conservation area or under an Article 4 direction, and the dormer stays within 40 cubic metres (terraced) or 50 cubic metres (other houses), below the ridge and off the front slope.
Does a loft conversion need planning permission in a conservation area?
A dormer, hip-to-gable or mansard does, because roof extensions are not permitted development on land in a conservation area. Rooflights often do not, unless an Article 4 direction removes that right.
How do I find out if my house is in a conservation area?
Birmingham City Council publishes a map and appraisal for each of its 29 conservation areas; Solihull Council does the same for its 20. If you are unsure, the council's planning team can confirm it for your address.
Is a Lawful Development Certificate worth getting?
Yes. It confirms in writing that the conversion is permitted development, settles any doubt about the volume calculation before you build, and is often requested by buyers' solicitors when the house is sold.
Do I need Building Regulations if I do not need planning permission?
Yes. Every loft conversion that creates a room needs Building Regulations approval, whatever the planning position.