Two quotes for the same windows can look surprisingly different. Discover what to compare before choosing bespoke timber sash replacements for your London home.
You have counted the windows, described your home and requested quotations. Then the figures arrive, and they are surprisingly far apart. For homeowners planning replacement timber sash windows in South West London, the important question is not simply which quote is cheapest. It is whether the quotations describe the same finished installation.
Online price guides can be useful starting points, but a headline price rarely explains every assumption. A tall window in a Battersea terrace, an upper floor opening in Putney and a detailed bay in Clapham can involve different manufacturing and installation requirements. Here is how to make a meaningful comparison before committing to your new windows.
Start With Exactly What Is Being Replaced
Ask each supplier to identify the windows included and describe the replacement work clearly. The quotation should distinguish the new frame, moving sashes, glazing and hardware, rather than relying on a broad description such as new sash windows.
Check that every supplier has allowed for the same openings. A bay can contain several individual windows, so one quoted bay is not necessarily comparable with one quoted window elsewhere in the house. A simple room by room schedule prevents misunderstandings.
Supply only pricing is also different from a quotation for survey, manufacture and installation. Compare the complete agreed scope, not an isolated product price.
Compare Dimensions and Heritage Details
Bespoke timber windows are made to suit their openings. Size, proportions and decorative details all affect the amount of material and work involved. Two windows that look similar from the pavement may have different measurements or internal surrounds.
For a period home, ask whether the price includes the specified glazing bar arrangement, sash horns, mouldings and visible frame profiles. These details influence how convincingly the replacements sit within the original architecture.
If drawings are required for a consent application or design approval, establish who provides them and whether that work is included. Do not assume that a lower price covers the same level of detailing.
Check the Timber, Glazing and Finish
A quotation should identify the proposed timber and finishing system. The words timber sash window do not, on their own, tell you which material or paint specification has been allowed for.
Glazing deserves the same attention. Compare the actual proposed construction and any stated performance, rather than assuming that all double glazing is equivalent. If a figure describes the glass alone, it should not be read as a performance figure for the complete window.
For a street facing room near a busy road, explain your noise concerns at the survey and ask what the proposed specification can reasonably achieve. For heritage constrained openings, confirm that the glazing and profiles are compatible with any agreed design requirements.
Record paint colours, internal and external finishes, and hardware choices before comparing totals. Optional finishes or fittings can otherwise appear as additional costs after you thought the specification was settled.
Look Beyond the Window to the Installation
Access can change the practical demands of a London installation. Upper floors, a narrow entrance, limited parking or restricted working space may require different arrangements. Ask how the site will be assessed and whether any access equipment or parking costs are included.
Clarify who removes and disposes of the old windows, what protection will be used inside the home and what condition the surrounding area will be left in. These questions concern the scope of the replacement installation, not just the appearance of the new joinery.
The phrase making good can mean different things. Ask whether it includes the affected plaster surfaces, trims and final decoration, or whether some finishing work remains your responsibility. Obtain the answer in writing so that an apparently cheaper quotation does not leave an unexpected separate bill.
Separate Permissions From Installation Certification
A replacement project may involve more than one approval. Planning controls, listed building consent and leasehold permissions depend on the property and proposed work. Check the requirements with the relevant authority or property representative before authorising manufacture.
Building regulations certification is a separate matter. Ask how compliance will be handled for your particular installation and what documentation you will receive. Do not assume that an installation certificate replaces planning permission or freeholder approval.
For a conservation area home in Richmond or Wandsworth, identify the requirements for that address rather than relying on a general statement about the borough. Any drawings, applications or external fees should be clearly assigned within your project budget.
Compare Guarantees and Payment Terms
Read the written guarantee rather than comparing only its headline length. Check which parts of the installation are covered, any conditions and how a claim would be handled. Where insurance backing is described, ask for the relevant terms and eligibility details.
Review the deposit, payment stages and the point at which the specification becomes final. Ask how changes after approval would be priced and how long the quotation remains valid.
Manufacturing and installation dates should be discussed separately. A quoted lead time may start after a technical survey or design approval, not from your first enquiry. Knowing the starting point helps you compare proposed schedules fairly.
Use a Simple Comparison Checklist
Place the quotations side by side and check the same items: window quantities and dimensions, frame and sash specification, timber, glazing, heritage details, paint finish, ironmongery, access, removal, disposal, finishing work and certification.
Then check VAT, any exclusions, payment stages, guarantee terms and the proposed timetable. Ask suppliers to clarify missing items rather than guessing that they are included.
A larger total is not automatically better value, and a lower total is not automatically a warning sign. The useful comparison is the complete agreed specification and responsibilities. There is no single reliable price for every bespoke timber sash window in South West London.
Get a Budget Based on Your Own Home
Sash Timber Windows offers bespoke timber sash window survey, design, manufacture and installation across South West London, with heritage detailing and a choice of ironmongery. Its online price calculator can help you start planning, while a property survey and written quotation establish the proposed work for your home.
Bring a list of the windows you want replaced, photographs of the existing profiles and any known consent requirements. Clear information at the start makes it easier to receive a useful quotation and choose your replacement windows with confidence.
