Joinery, Windows and Doors in London Renovations: Specification Guide

**Timber sash windows:** The original window form of London Victorian and Edwardian terraces. Sliding sash windows (double-hung sash) are the defining feature of the London terrace street scene and are strongly protected in Conservation Areas.

• •**Timber sash — new or refurbished:** Original sash windows can be refurbished (re-sashcord, re-glazing, draught-proofing) at relatively low cost. Full replacement in a like-for-like timber sash (softwood painted or hardwood) is more expensive than uPVC or aluminium but often required in Conservation Areas.
• •**Slim double-glazed timber sash:** Modern slim-profile double-glazed sash units in softwood or hardwood replicate the original appearance while improving thermal performance. Cost: £1,200–£2,500 per window supply only (softwood); £2,000–£4,000 in hardwood.

• **Aluminium windows:**
• Slim-profile aluminium windows (typically powder-coated anthracite grey or black externally) are popular for contemporary extensions and rear elevations of London properties:
• •Slim sightlines — better glass-to-frame ratio than uPVC
• •Low maintenance (no painting or staining)
• •Can replicate traditional profiles (Crittall-style steel window aesthetic) at lower cost than steel
• •Planning: acceptable in Conservation Areas on rear elevations where not visible from the public highway; front elevations often require like-for-like replacement
• •Cost: £1,500–£3,500 per window supply only depending on size and specification

• **uPVC windows:**
• The most cost-effective specification:
• •Wide range of profile shapes and colours available
• •Lower cost than timber or aluminium: £400–£1,200 per window supply only
• •Planning: generally not accepted as a like-for-like replacement for timber sash in Conservation Areas on front elevations
• •Suitable for non-sensitive locations and rear elevations

**Secondary glazing:** For listed buildings or Conservation Area properties where double-glazing the original windows is not acceptable, secondary glazing (an internal second pane within the existing reveal) provides meaningful thermal improvement (reducing heat loss through the window by approximately 60–70%) without altering the external appearance. Cost: £400–£1,200 per window supply and install.

**Building Regulations and replacement windows:** Replacement windows must meet minimum thermal performance requirements under Building Regulations Part L. Self-certification via a FENSA or CERTAS registered installer satisfies the Building Regulations requirement without a separate Building Control application.

• **Bifold doors:**
• The most popular glazed opening for London rear extensions and kitchen-diners:
• •Fold and stack to one or both sides of the opening
• •Available in aluminium (most common), timber, or timber-aluminium composite
• •Opening widths up to approximately 7–8m (limiting factor is structural span and stack space)
• •Key considerations: stack space (bifold panels stack inside or outside — inside stacking reduces headroom clearance at threshold; outside stacking reduces patio width); weather sealing performance (lower than sliding doors on exposed elevations); threshold detail (floor finishes inside and outside need to be coordinated at design stage)
• •Cost: aluminium bifold door 3–4m wide: £4,000–£8,000 supply only

• **Sliding doors / lift-and-slide doors:**
• The premium alternative to bifolds:
• •Individual panes slide horizontally — no stacking inside the room, better weather sealing, narrower sightlines
• •Lift-and-slide operates by lifting the door off the sill seal for smooth operation, then lowering it back onto the seal when closed — better weatherproofing than standard sliding
• •Typical widths: 2.4m to 6m+ (wide-span sliding systems available from specialist suppliers)
• •Cost: aluminium sliding or lift-and-slide 3–4m wide: £5,000–£12,000 supply only

• **Front doors:**
• The front door is often the strongest aesthetic element of a London terrace. Options:
• •**Timber painted:** The traditional choice — warm appearance, paintable to any colour, period-appropriate for Victorian properties. Good quality hardwood front doors last 40–60 years. Cost: £1,500–£5,000 supply only.
• •**Aluminium composite:** Aluminium-clad timber or composite core — thermally efficient, lower maintenance than solid timber while retaining a traditional appearance. Cost: £2,000–£5,000 supply only.
• •**uPVC:** Most cost-effective; planning-sensitive in Conservation Areas. Cost: £800–£2,000 supply only.

**Planning for external door replacement:** In Conservation Areas, replacing external doors (front or rear visible from the public highway) in a material or style that does not match the original character of the property typically requires planning permission. Like-for-like replacement (same material, colour, style, proportions) is usually acceptable without permission.

Internal joinery — doors, skirtings, architraves, dado rails, and staircases — defines the interior character of a London home. In Victorian and Edwardian properties, original joinery in good condition is a significant asset.

• **Internal doors:**
• •**Original Victorian/Edwardian panelled doors:** 4-panel or 6-panel hardwood or softwood doors, typically solid pine. Where originals are in place, restoration (stripping to bare wood or repainting) is strongly preferred to replacement.
• •**New doors to match period:** Period-style panelled doors in solid softwood or engineered hardwood are available from specialist suppliers and should match the profile of the originals (panel depth, moulding profile, proportion). Standard off-the-shelf 'colonial' doors do not match Victorian profiles and look incongruous.
• •**Contemporary doors:** For contemporary extensions or modern refurbishments where a period-style house is being updated: flush internal doors in veneer or painted MDF, concealed frame systems.

**Skirtings and architraves:** The profile of skirting boards and door architraves in Victorian and Edwardian London houses is typically ogee or torus profile, in substantial section (150–230mm height skirting). Modern standard skirtings (50–75mm MDF, square-edged) are immediately out of character with period properties.

For renovation work in period properties: replicate the existing profile (measure the section and order matching profiles from a specialist supplier or local joinery workshop). For full renovations where all joinery is being replaced: select a period-appropriate profile of the correct scale for the room.

**Staircases:** Original Victorian staircases are typically close-string softwood with turned newels and balusters. Where renovation reveals the original staircase under carpet, restore if possible — sanded treads, painted risers and strings, restored balusters. Where the staircase is at end of life or is being relocated, new staircases in the period style are available from specialist suppliers.

**Fire doors:** Where Building Regulations require fire doors (escape routes in HMOs, between an integral garage and the house, loft conversion escape route), these must be FD30S rated fire-check doors with appropriate ironmongery. They can be finished in a period style on the visible face while meeting the fire rating requirement.