Updating Interior Doors in Your Home

Interior doors shape both the aesthetics and day-to-day practicality of a home, yet they are often the last thing homeowners consider during a renovation. Questions about which style suits a Victorian terrace or whether a solid-core door needs a new frame typically arise during a kitchen remodel, loft conversion, or whole-house refresh — moments when existing doors suddenly look out of place or simply no longer function properly.

Key points

• Standard UK internal door sizes are 1981 mm × 762 mm and 1981 mm × 686 mm, but pre-1970s properties frequently have non-standard openings that need made-to-measure doors.
• Fire doors rated FD30 are required under Building Regulations Approved Document B in specific locations — including between an integral garage and a habitable room, and on escape routes in flats on upper floors.
• Solid-core internal doors typically weigh 35–45 kg; hollow-core equivalents weigh around 10–15 kg. Heavier doors need correctly rated hinges (usually three 76 mm or 100 mm hinges) and a structurally sound lining.
• Door linings often need replacement when upgrading from hollow-core to solid-core, as original linings in older homes may be too slim or damaged to carry the additional load.
• Replacing standard interior doors does not require building regulations approval in most cases, but installing or replacing fire doors on an escape route must comply with Approved Document B.

Hollow-core, solid-core, or glazed: choosing the right door type

The three common interior door constructions each suit different situations. Understanding the trade-offs before purchasing avoids costly returns or a poor result.

If you are unsure whether a location legally requires a fire door, check Building Regulations Approved Document B or consult a qualified installer before purchasing.

How to measure for a replacement door

Measuring accurately before ordering is the most common point of failure in door upgrades. Measure the frame opening (the reveal), not the existing door leaf.

1. Measure the width at the top, middle, and bottom of the opening — use the narrowest figure.
2. Measure the height on both sides — use the shorter measurement.
3. Note the thickness of the existing door (typically 35 mm for standard doors, 44 mm for fire doors).
4. Check the door lining rebate depth — standard UK linings are typically 107 mm or 133 mm depending on wall thickness.
5. If measurements fall between standard sizes, order made-to-measure rather than over-trimming. Check the manufacturer's data sheet — some engineered doors have a trim allowance of just 6 mm per side, and some cannot be trimmed at all.

For pre-1919 terraces and inter-war properties, door openings are often out of square. Made-to-measure or custom-trimmed doors are frequently the only practical solution.

Door styles and what suits your property

Style choices work best when they reflect the property era and the existing architectural details.

• Victorian and Edwardian homes: four- or six-panel moulded doors or original period-style hardwood. Flush doors can look out of place alongside original cornicing and skirting.
• 1930s semi-detached: three- or four-panel doors with gentle Art Deco lines, or glazed doors to complement original picture rails.
• 1960s to 1980s estates: flush doors or simple contemporary styles suit the architecture. Replacing with panel doors can appear mismatched unless the whole interior is being updated at the same time.
• New-build flats: flush, contemporary, or slim-framed glazed doors. Standard metric sizes usually fit without modification.

Ironmongery — handles, hinges, latches — should be consistent throughout an open-plan floor and ideally match other metals in the space such as taps, light switches, and radiator valves.

Homeowner checklist: before you buy or install

• Measure the opening width, height, and thickness at three points each
  
• Check whether the location legally requires a fire door (garage-to-house link, flat escape route, licensed HMO)
  
• Assess the condition of the existing lining and frame — look for rot, twist, or structural damage
  
• Confirm door construction (solid-core or hollow-core) and the correct number and size of hinges
  
• Establish whether you need a pre-hung door or a door leaf only
  
• Confirm the trim allowance with the manufacturer before cutting
  
• Choose ironmongery before installation — handles and latches affect the mortice size and door edge specification
  
• If the door includes glazed panels, confirm the glass specification complies with Approved Document N (safety glazing in critical locations)
  

When to get professional help

Most interior door replacements are manageable for a competent DIYer or general handyperson. Professional help is advisable when:

• The work involves fire doors on an escape route or between a garage and living space — incorrect installation can void the fire rating and create a safety risk.
• The opening requires structural adjustment such as widening or raising, which may need structural engineer input and building regulations approval.
• The lining or frame shows signs of rot or structural damage, particularly in solid-wall or timber-frame constructions.
• You are fitting doors in a listed building — even internal alterations may require listed building consent from your local planning authority.
• You have several doors to hang and lack the tools or experience to achieve a consistent, gap-free fit throughout the property.

How Housey can help

If you need a professional to supply and fit new interior doors — particularly fire doors, made-to-measure installations, or a full programme of replacements across the property — Housey connects you with vetted window and door installers in your area. Submit a request to receive quotes from qualified local professionals.

Frequently asked questions

Do I need building regulations approval to replace interior doors?

No, in most cases replacing like-for-like interior doors does not require building regulations approval. The exception is fire doors on escape routes — replacing these must comply with Approved Document B, and the installation may be subject to building control inspection if it is part of a wider regulated project such as a loft conversion.

How much does it cost to replace interior doors in the UK?

A hollow-core door leaf typically costs £30–£80; a solid-core or engineered door usually costs £80–£250. Professional installation adds roughly £60–£120 per door for a straightforward fit, rising for made-to-measure doors or lining replacement. Indicative UK costs, last reviewed 2026-05-19. Always obtain at least two quotes before proceeding.

Can I hang interior doors myself?

Yes, if you have basic DIY skills, the right tools — a plane, saw, drill, and spirit level — and accurate measurements. Fire doors should only be fitted by someone familiar with the relevant requirements; a gap of more than 3 mm around the door leaf can compromise the fire rating and render the door non-compliant.

What is the difference between a pre-hung door and a door leaf?

A pre-hung door is supplied already fitted into its frame or lining, making installation simpler where the existing lining is damaged or non-standard. A door leaf is the door alone, fitted into an existing lining. Pre-hung doors are often more practical for replacements where the original frame cannot be reused.

Sources and further reading

• Building Regulations Approved Document B — Fire Safety — GOV.UK
• Building Regulations Approved Document N — Glazing Safety in Relation to Impact — GOV.UK
• British Woodworking Federation — Door Guidance — British Woodworking Federation