Can I replace sash windows in a conservation area?

Usually yes, if the replacements match the originals in material, profile and glazing bars. Many local planning authorities accept slim double-glazed timber sashes. We record the existing windows and coordinate with the conservation officer where consent is needed.

Are timber windows as efficient as uPVC?

Modern timber windows with slim double glazing and draught seals meet the same Part L thermal requirements as uPVC, while lasting longer and suiting period buildings.

How long does bespoke joinery take to make?

Most window and door orders are manufactured within four to eight weeks of survey, depending on the number of units and the timber and glazing specification.

Build & Refurbish

Bespoke joinery & window frames

Timber joinery made in our workshop to the millimetre. Sash windows, doors, staircases and fitted furniture that match the building rather than fight it.

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Timber sash window frame on a joinery bench with hand planes and shavings

In short

What bespoke joinery does MJ Site Solution make?

MJ Site Solution makes and installs made-to-measure timber joinery: sash and casement windows, internal and external doors, staircases, and fitted wardrobes and alcove units. Existing profiles are recorded so replacements match period properties, and replacement windows meet Part L thermal requirements, including in conservation areas.

Last reviewed 21 September 2026

Products: Sash and casement windows, doors, staircases, fitted units
Manufacture: Made to measure in our own workshop
Regulations: Part L thermal performance
Conservation areas: Like-for-like replacements, planning coordinated

Scope

What is included.

Timber sash and casement windows
Like-for-like replacements for period properties
Internal and external doors and frames
Staircases, handrails and balustrades
Fitted wardrobes, alcove units and shelving
Skirting, architrave and mouldings matched to profile

Timber sash and casement windowsLike-for-like replacements for period propertiesInternal and external doors and framesStaircases, handrails and balustradesFitted wardrobes, alcove units and shelvingSkirting, architrave and mouldings matched to profile

Delivery

How we deliver it.

Newly installed bespoke timber sash window in a freshly painted reveal

Step 01 / 03

Measure

Openings surveyed and existing profiles recorded, so new work matches the old.

33%

Step 02 / 03

Make

Manufactured in our workshop from selected, seasoned timber.

67%

Restored London Victorian terraced house with new painted sash windows and black front door

Step 03 / 03

Fit

Installed, sealed and finished by the joiners who made it.

100%

Standards & compliance

Replacement windows meet Part L thermal requirements. Conservation-area and listed-building work coordinated with the local planning authority.

Questions

Bespoke joinery & window frames: common questions.

Usually yes, if the replacements match the originals in material, profile and glazing bars. Many local planning authorities accept slim double-glazed timber sashes. We record the existing windows and coordinate with the conservation officer where consent is needed.
Modern timber windows with slim double glazing and draught seals meet the same Part L thermal requirements as uPVC, while lasting longer and suiting period buildings.
Most window and door orders are manufactured within four to eight weeks of survey, depending on the number of units and the timber and glazing specification.

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