Fire Safety in London Renovation: What the Regulations Require

Fire safety regulations are among the most commonly misunderstood aspects of residential renovation in London. Since the Grenfell fire in 2017 and the subsequent legislative and regulatory response, requirements have become more demanding and enforcement more rigorous. This guide covers the key points for renovation projects in private residential properties.

When fire safety regulations apply

Part B of the Building Regulations covers fire safety and applies whenever building work is carried out. For renovation projects, this means any work that affects the means of escape, fire resistance of the structure, fire detection, or spread of flame — whether or not you are making structural alterations.

In practice, common renovation triggers include:

• —Adding a loft conversion or basement (new habitable space)
• —Changing the use of a room (e.g. dividing a house into flats)
• —Installing or extending a central heating system that requires a new boiler flue
• —Replacing a roof that was previously providing structural fire resistance
• —Refurbishing a flat in a block where the common areas and escape routes are affected

For a single-occupancy house, Part B requirements are more straightforward than for houses in multiple occupation (HMOs) or residential buildings over 11 metres in height.

Smoke and heat detection

Any renovation project requiring Building Regulations approval triggers the requirement to bring the property's smoke detection up to current standards. For residential properties, BS 5839-6:2019 applies:

• —Interlinked smoke alarms in the ground floor hallway and each storey landing
• —A smoke alarm in all principal habitable rooms (living rooms, dining rooms — typically Grade D1, LD2)
• —A heat alarm in the kitchen
• —Battery backup required (mains-powered with tamper-proof backup)

This applies even if you are renovating only one room — the detection upgrade is required across the whole dwelling. Many clients are unaware of this and are surprised when the building control inspector flags it.

Means of escape and protected routes

In loft conversions and basement conversions, the means of escape from the new storey is a primary design concern.

For loft conversions: - A protected escape route (fire-resisting construction) must connect the new floor to the final exit - In most cases this means upgrading the existing staircase enclosure to 30-minute fire resistance - Roof windows used as escape openings must comply with Approved Document B minimum dimensions

For basement conversions: - Emergency escape is required — either through the stair to the ground floor or through a compliant window directly to a place of safety - Alternative means of escape through subterranean light wells are accepted in some configurations

Fire doors

Wherever a fire-resisting structure is required (protected staircase enclosure, between a garage and the house, between a conversion and the existing dwelling), fire doors are required. These must be certified to the appropriate standard, correctly hung, fitted with self-closing devices, and fitted with intumescent strips and cold smoke seals.

Supply and fit of a certified FD30S door set (door, frame, self-closer, seals) is typically £600–£1,200 depending on specification.

Specific requirements for buildings over 11 metres

The Building Safety Act 2022 introduced the Higher-Risk Buildings regime for residential buildings over 18 metres. For the 11–18 metre band, local authorities have stronger oversight powers and certain external wall works require a competent person sign-off.

If your project involves a property in a block of flats or a tall building, fire safety compliance needs to be addressed early in design — not as an afterthought.

How this affects project planning

The most common fire safety-related problem we see is projects that are designed without adequate fire safety input, discover the requirement during building control inspection, and then have to retrofit solutions that are more costly and less elegant than they would have been if designed in from the start.

At ASAAN, fire safety compliance is part of the technical design process on every project. We include building regulations compliance as a standard part of our service, not an add-on.

If you are planning a renovation that involves structural alterations, loft or basement conversion, or any change of use, contact us for a consultation.