Small repairs, such as refixing slipped tiles or renewing a flashing, do not usually need building regulations approval. Official guidance says approval is normally needed if the work affects 50% or more of the roof, or 25% or more of the whole building envelope, or if the new covering is 15% or more heavier than the old one. Above those limits, Part L normally expects the insulation of the whole roof to be upgraded. You can either notify your council's building control, or use a roofer registered with a government-authorised competent person scheme, who can sign off their own work.
Building regulations are separate from planning permission. For planning, see our guide do I need planning permission for roof work?.
When does roof work need building regulations?
The official limits
The Planning Portal says that repairing or re-covering an existing pitched or flat roof does not normally need building regulations approval if:
- less than 25% of the total building envelope is affected (the envelope means the walls, floor, roof, windows, doors, roof windows and rooflights together), and
- less than 50% of the roof is affected.
Approval is needed if:
- the work goes beyond either of those limits
- you make structural alterations
- the new covering increases the weight of the roof covering by 15% or more
- the new covering would perform significantly differently in a fire
So everyday repairs, such as refixing slipped tiles, repointing a ridge or renewing a flashing, normally fall well inside the limits. Re-covering a whole roof, or most of one, normally does not.
Councils can differ
Some council building control teams set out their own guidance, and a few take a stricter view of what counts as a repair. If you are unsure, check with your local council's building control team, or make sure your roofer is handling it.
The thermal upgrade under Part L
When you renovate a roof, Approved Document L (conservation of fuel and power) normally expects the insulation to be brought up to current standards. The key points are:
- Where you renovate more than 50% of the surface area of the roof (the "thermal element"), or more than 25% of the surface area of the whole building envelope, the whole roof should normally be upgraded to the required standard.
- The upgrade is expected where it is technically, functionally and economically feasible. If the full standard cannot reasonably be met, the insulation should be improved as far as is practical.
- On a pitched roof, that might mean extra insulation at ceiling level or between and over the rafters. On a flat roof, it often means a "warm roof" build-up with insulation boards above the deck.
Adding insulation changes how moisture moves through the roof, so ventilation matters too. Re-roofing often needs better ventilation, such as eaves, tile or ridge vents, or a breathable underlay, to stop condensation.
Structure, weight and fire
- Heavier coverings. If the new covering increases the weight of the roof covering by 15% or more, for example some concrete tiles in place of slate, you need approval and the roof structure must be shown to cope. It may need strengthening, so get it checked by a structural engineer or surveyor before work starts.
- Structural changes. Altering rafters, removing a chimney or changing the roof shape needs building control involvement.
- Fire. The new covering should not perform worse in a fire than the one it replaces.
Who signs it off?
You have two main routes:
- 1A roofer registered with a competent person scheme. Members of a government-authorised roofing scheme can sign off their own work as meeting the building regulations, so you do not need to apply to building control yourself. Your roofer, or their scheme, should notify the council and give you a certificate of compliance once the work is finished.
- 2Building control. If your roofer is not registered, you or your roofer apply to your council's building control (or a registered approved inspector) before work starts. They inspect the work and issue a completion certificate.
Without the right certificate, you may run into problems when you sell your home. Councils can also take action over unauthorised work.
Party walls
If you live in a semi-detached or terraced home, re-roofing can involve the wall you share with your neighbour. Under the Party Wall etc. Act 1996, work such as cutting into a party wall, raising it, or cutting into a neighbour's wall to insert a flashing usually requires you to serve notice at least two months before the work starts, unless your neighbour agrees in writing. Routine re-covering that does not touch the party wall is less likely to be covered, but it is worth checking early.
In Essex, Hertfordshire and Cambridgeshire
The age of the roof makes a big difference to how much upgrading is involved.
- In Potters Bar, many 1930s roofs still have their original tiles and battens, often with no proper underlay. Stripping and relaying them on new battens and breathable membrane is a common job, and it is the point where insulation and ventilation need thinking about.
- In Chelmsford, Victorian and Edwardian terraces around Moulsham and the West End have slate roofs suffering from nail fatigue, often leading to full re-slating.
- Cambridge terraces around Romsey and Mill Road often have rear extensions with tired felt flat roofs, where re-covering can bring in a warm roof upgrade.
- In Hemel Hempstead, new town neighbourhoods such as Adeyfield and Bennetts End have many flat-roofed garages, porches and extensions due for replacement.
- Braintree has large estates from the 1960s onwards with concrete tiles and felt garage roofs, alongside old clay tile roofs in the town centre and Bocking, where building control may take a more flexible approach on historic buildings.
How First4Roofcare can help
We explain what building regulations apply to your job before we start, including insulation and ventilation, and make sure the right sign-off is arranged. Whether you need a new roof or a replacement EPDM flat roof, book a free survey and we will give you a clear written quote.