Drylining and building regulations: fire, sound and thermal rules explained

Updated 6 November 2026 · By the Drylining team

Short answer: Most like-for-like drylining in an existing home does not need building regulations approval, but approval is usually required when work forms part of a loft conversion, extension or conversion to flats, affects a fire escape route or an integral garage, or renovates 25% or more of an external wall. The relevant parts in England are Part B for fire, Part E for sound and Part L for energy.

When drylining is usually fine without approval

Re-lining internal walls with plasterboard after stripping old plaster
Overboarding ceilings in an existing house
Building a simple non-loadbearing partition that does not affect escape routes, light or ventilation
Boxing in pipes

Even where approval is not needed, the work should still be safe and should not make the building worse in terms of fire, sound or ventilation.

When building control is usually involved

Situation	Main regulation	What it usually means for drylining
Loft conversion	Part B fire, Part L energy	Fire-rated floor and protected escape route, insulated slopes and walls
Extension	Part L energy, Part B fire	Insulated walls and ceilings meeting current targets
House converted into flats	Part E sound, Part B fire	Separating walls and floors with sound testing, fire-rated construction
Integral garage wall or ceiling	Part B fire	Fire-resisting construction between garage and house
Renovating 25% or more of an external wall	Part L energy	Insulation to the renovation U-value where practical
New partition creating an inner room or blocking an escape route	Part B fire	Layout may need changing or extra fire measures

Fire-rated walls and ceilings

Approved Document B requires certain walls and floors to resist fire for a set time, most commonly 30 minutes in houses. Examples include the wall and ceiling between an integral garage and the house, the enclosure to a protected stair in a loft conversion of a two-storey house, and floors and separating walls in flats. A fire rating comes from a complete tested system: the right board type and thickness, the right frame, fixings at the specified centres, sealed joints and fire-stopping at gaps and service penetrations. Swapping one component can invalidate the rating.

In practice this means using fire-rated board where the specification calls for it, rather than standard board of the same thickness, and following the manufacturer's tested system details for stud size, layers and screw centres. Gaps where pipes and cables pass through a fire-rated wall or ceiling need sealing with a suitable fire-stopping product. Downlights in a fire-rated ceiling usually need to be fire-rated fittings or have fire hoods fitted. Loft hatches in a fire-rated ceiling may also need to be fire-resisting.

Sound rules

Approved Document E covers sound between dwellings in new homes and conversions, and within new homes for internal walls next to bedrooms and rooms containing a WC. Separating walls in new homes need to achieve at least 45 dB airborne sound insulation on site, and 43 dB in conversions, normally proven by pre-completion testing. Ordinary partitions in an existing house are not covered, but conversions and new flats are.

Thermal rules

Part L applies to extensions and conversions, and to renovating a thermal element, such as adding a new lining to an external wall, when 25% or more of the wall is affected. The target for internal insulation of a solid wall is 0.30 W/m²K where practical. Insulated drylining needs careful vapour control so meeting the energy rule does not create a condensation problem.

Other things to check

Electrical work: moving sockets is often minor, but new circuits may be notifiable under Part P
Ventilation: a new partition must not leave a room without required ventilation or a window
Listed buildings: internal alterations usually need listed building consent
Flats: leases often control alterations to walls, floors and ceilings
Wales, Scotland and Northern Ireland have separate regulations and guidance

If you are unsure, a short call or email to your local building control body before work starts costs nothing and avoids problems when you come to sell.

How approval works in practice

In England, building control is provided either by the local authority or by a registered building control approver, the private alternative. For domestic work there are two common routes. A full plans application involves submitting drawings and specifications for approval before work starts, which suits larger or more complicated projects such as loft conversions. A building notice lets smaller jobs start after notice is given, with the details checked on site, and is only available for some types of work.

Apply or give notice before the drylining starts, not after
Expect inspections at key stages, often before walls and ceilings are closed up
Keep product data sheets for fire-rated, acoustic and insulated boards used
Ask for sound test results where Part E testing applies
Keep the completion certificate safely, because buyers' solicitors will ask for it

Work that should have had approval but did not can cause delays when the property is sold, and the local authority can in some cases require it to be opened up or altered. Fees vary by council and project size, so ask for a quote from the building control body when you apply.