Buying new windows is a six-stage process: decide which windows need replacing and prioritise them, choose the right window type for each room, choose materials and glazing specifications, get multiple quotes from FENSA or Certass registered installers, compare quotes properly (not just headline price), and confirm the installation timeline and warranty. The whole process typically takes 8-16 weeks from initial decision to installation: 2-4 weeks for research and quotes, 4-8 weeks for manufacture, 1–2 weeks for installation. Key decisions are property style (which determines acceptable window types), room function (which determines best opening type), material (PVC, timber, or alu-clad), glazing (double or triple), and installer choice. The biggest mistakes are rushing the decision, taking the lowest quote without comparing specifications, and under-specifying windows on principal elevations.
Most homeowners over-estimate how many windows need replacement. A careful survey often shows that 40–60% of windows are sound enough to wait several years, even when the house feels generally in need of new windows. Prioritising correctly saves significant budget for the windows that really matter.
Walk through the house with a notepad. For each window, note:
Even within the urgent category, order matters. Replace first:
Less-used rooms (guest bedrooms, utility rooms) can often wait even if their windows are in similar condition, because the comfort impact is lower.
Window type — casement, sash, tilt-and-turn, picture, etc. affects both appearance and function. For period properties, the property style usually narrows the choice significantly.
Property period and architectural character determine which window types are appropriate. Listed buildings and conservation areas have specific requirements; unlisted period properties have more flexibility but still benefit from sympathetic choices.
Different rooms benefit from different window types. Bedrooms may suit tilt-and-turn for cleaning access; bathrooms suit small awning windows; living rooms benefit from large casements or picture windows. The "How to choose window type" guide covers this in detail.
Few homes use only one window type throughout. Most benefit from 2–4 different types matched to different rooms and elevations. Trying to use a single type everywhere usually means over-specifying some rooms and under-specifying others.
Premium specifications on principal elevations and main rooms, standard specifications elsewhere. This deploys budget where it has most impact and avoids wasting investment on windows where the difference is invisible.
Three quotes is the standard recommendation and works well for most projects. More than three usually adds complexity without adding clarity; fewer than three risks missing a significantly better option. For large or complex projects (heritage buildings, large extensions), four to five quotes may be worthwhile.
Quotes are only as good as the information installers receive. Provide:
Three quotes for "new windows" can vary by 50% or more without any of them being wrong. The difference reflects different specifications — frame profile, glazing thickness, security level, finish quality, installation approach. Comparing only the headline price ignores what is being compared.
Make a comparison table with these columns for each quote:
A quote that is 20% higher but includes a substantially better warranty, higher cylinder rating, and full making-good of internal finishes may be the better choice. Compare like for like before deciding.
Most installers send a surveyor to take accurate measurements before manufacture. This is the chance to confirm specifications and catch any misunderstandings before the windows are made. Be present for the survey, walk through every window, and confirm every detail.
Typical manufacture lead times are 4-8 weeks for standard specifications, 8-12 weeks for custom sizes or finishes, and 12+ weeks for heritage or specialist installations. Plan the installation to follow the manufacture period - windows ordered in October are typically installed in December or January, not always ideal weather for the work.
Installation of multiple windows typically takes 1–5 days depending on the number and complexity. Each window typically takes 2-4 hours of actual installation time. Plan for:
FENSA or Certass registered installers register the work with the relevant scheme, providing a certificate that confirms Building Regulations Part L compliance. This certificate is needed if you sell the property later — keep it with property documents.
Within 24 hours of installation, check every window:
Report any issues immediately - installer warranties typically have specific time limits for snagging items, and prompt reporting gets faster resolution.
Where whole-house replacement is beyond budget, phasing across 2-3 years works well. Replace the worst windows first, then continue in priority order. The downside is two or three separate installations (each with set-up cost), but the cash flow advantage often justifies this.
Within a single installation, specification varies window by window. Premium specifications on principal elevations (front of house, main living room) and main bedrooms. Standard specifications on side and back of house, less-used rooms. This deploys budget where it matters most.
FAQ
How long does the whole window buying process take?
›
Should I tell installers my budget upfront?
›
Are window salespeople really commission-driven?
›
Can I install windows myself to save money?
›
