The short answer
Building regulations and planning permission are two separate things, and they apply differently to bifold doors. Building regulations always apply: every new bifold must meet thermal-performance targets (Part L glazing / U-values), structural support and safety glazing, and a FENSA-registered installer can self-certify this. Planning permission usually is not needed if you fit the doors into an existing opening of the same size or smaller, under permitted development. It changes if you widen the wall opening — which needs a structural lintel and building-regs sign-off, and can need planning if it alters the external appearance — or if your home is listed, in a conservation area, or a flat, where stricter controls apply and you should check with the local planning authority first.
Two questions come up on every bifold job: do I need building regs, and do I need planning? Building regs always apply; planning depends on whether the opening is widened and where you live. The detail below is what matters.
The rules in brief
- Building regsalways apply (Part L, glazing)
- FENSA installercan self-certify the work
- Existing opening, same sizeno planning (usual)
- Widened openinglintel + building regs; may need planning
- Listed / conservation / flatcheck local authority first
Building regulations and Part L
Unlike planning, building regulations apply to every replacement door, including bifolds. The doors must meet Part L thermal-performance targets (a maximum U-value for the glazing), provide adequate structural support, and use safety glazing in the critical areas. The straightforward route is to use a FENSA-registered installer, who can self-certify the work to building control and issue a certificate — which you'll want when you come to sell. If the installer is not registered under a competent-person scheme, the work has to be notified to building control separately.
Structural openings and when planning applies
Fitting bifolds into an existing opening of the same size or smaller is normally permitted development and needs no planning permission. The moment you widen the wall opening, two things change: you need a structural lintel sized for the new span with building-regs sign-off, and if the change alters the building's external appearance you may need planning permission as well. Stricter rules apply to listed buildings (listed building consent), conservation areas and national parks, and flats and apartments, which often do not share a house's permitted-development rights — in all of these, check with your local planning authority before starting. A structural engineer's input is sensible whenever a load-bearing wall is opened up.
| Situation | What applies |
|---|---|
| Existing opening, same size, house | Building regs only — no planning (usual) |
| Widened opening, house | Lintel + building regs; planning may apply |
| Listed building | Listed building consent (usual) |
| Conservation area / national park | Check local authority first |
| Flat or apartment | Often needs planning — check first |
General guidance — confirm your own case with your local planning authority. Sources: Planning Portal and trade guidance.
Want a quote with building regs covered?
We'll match you with a FENSA-registered door installer who self-certifies the work, sizes any lintel, and flags any conservation-area, listed-building or flat check for your property.
Frequently asked questions
Do bifold doors need building regulations?
Yes. Every new bifold must meet building regs for thermal performance (Part L glazing / U-values), structural support and safety glazing. A FENSA-registered installer can self-certify the work and issue a certificate.
Do bifold doors need planning permission?
Usually not if you fit them into an existing opening of the same size or smaller, under permitted development. You may need planning if you widen the opening, or if your home is listed, in a conservation area, or a flat — check with the local authority first.
Do I need a lintel for bifold doors?
If you widen the wall opening, yes — a structural lintel sized for the new span is needed, with building-regs sign-off, commonly adding £500–£1,500 for the lintel. Fitting into an existing opening of the same size usually does not need new structural work.
Sources & further reading
Figures on this page are typical UK ranges drawn from published sources and depend on your specific opening and material. They are guidance, not a quotation.