Flush casement window installers for period and modern homes
Flush casement window installers who cover your postcode survey every opening and quote in writing for windows whose opening sashes close level with the frame. Pick your frame material in the form, then ask each installer for the same pane layout, so the quotes compare.
- Say "flush" on the call. When they ring to confirm the job, ask for flush sashes, not storm-proof
- Same spec on every quote. Opening plan, pane layout and frame colour, window by window
- Free and no obligation. Say no to every quote if none suit you
We are a free quote-matching service, not an installer.
The look
What makes a window a flush casement?
A flush casement's opening sash closes level with the frame, while a storm-proof casement's sash sits on top of the frame. Bassetlaw District Council's casement guidance says traditional casements "were always set flush with the frame or recessed when closed", unlike many modern "off the peg" storm-proofed windows.
Ask flush casement installers these questions before the survey, and get the answers in writing:
| On the quote | Ask |
|---|---|
| Sash position | Does every opening sash close flush with the frame outside, or does any sit proud? |
| Profile system | Which named frame system is it, and can you show me a corner sample? |
| Sightlines | How wide are the frame and sash, in millimetres, compared with my old windows? |
| Opening plan | Which panes are side hung, which are top hung and which are fixed? |
| Pane layout | How many panes per sash, and are the glazing bars real or applied? |
For standard storm-proof casements, see our page on casement window replacement.
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Frame material
Flush casements in uPVC, timber or aluminium
Flush casement installers quote in uPVC, timber or aluminium, and the frame material changes the upkeep, the lifespan and the frame width. The Energy Saving Trust describes each one:
| Frame | Energy Saving Trust | Ask the installer |
|---|---|---|
| uPVC | Doesn't need regular maintenance and can be recycled. | How wide is the sash next to my old timber one? |
| Timber | The more sustainable option; with maintenance it can last far longer than uPVC. Often used in conservation areas where the original windows were timber. | Which timber, which finish, and how often does it need repainting? |
| Aluminium | Slim, long lasting and recyclable. | What is the whole-window energy figure, frame included? |
Historic England says uPVC window components are weaker than timber ones, so the frames "tend to be much thicker" with different detailing. That is a reason to compare sightline sizes and a corner sample on every quote, not a verdict on any one product.
For timber, see our page on wooden window replacement. For slim metal frames, compare aluminium window installers.
Period homes
Are flush casement windows suitable for conservation areas?
Flush casement windows often suit conservation areas, but the council decides, not the installer. Speak to the council before you accept a quote.
Council design guides set out what a traditional casement looks like. Bassetlaw District Council's guidance, for example, says:
- traditional casements were side hung, and top hung windows "are often inappropriate in older properties";
- extra adornments such as drip mouldings "are not appropriate";
- glazing bars were mitred to the frame, and machine routering after assembly "will not be accepted".
Your own council's guide is the one that counts, so ask each installer to quote against it.
| Your home | What applies |
|---|---|
| Conservation area, England | The Energy Saving Trust says to contact your council's conservation officer for guidance. |
| Article 4 direction | Historic England says these directions can restrict even replacing a window with one of a similar design. Your local authority tells you whether one applies. |
| Listed building | Listed building consent is needed for work that alters the building and affects its character, windows included (Historic England). |
| Conservation area, Scotland | A front window needs no notification when it matches the old one on opening mechanism, the number, orientation and colour of panes, and the frame's dimensions and colour. The material need not match (Planning Circular 1/2024). |
The Scottish test reads frame width as well as material. A flush casement that keeps the old frame size and pane pattern is the kind of match it looks for. A different material that changes the frame width triggers prior approval, and the council has 28 days to say whether it needs to approve. See double glazing in Scotland for the full Scottish rules, or try our planning permission for windows checker.
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The rules
What every flush casement must meet
A flush casement meets the same building rules as any replacement window: an energy limit, ventilation, escape and safety glass, plus a sign-off. The rules are the same whether the sash is flush or storm-proof.
| Rule | What to see on the quote |
|---|---|
| Energy, England | 1.4 W/m²K or Window Energy Rating band B, under Approved Document L since 15 June 2023. Ask for the figure per window. |
| Energy, Scotland | 1.6 W/m²K or band C for replacement windows (Scottish building standards, clause 6.2.11). |
| Vents | LABC says a replacement window needs vents if the old one had them, and must not reduce the area that opens for ventilation. |
| Escape | An escape window can only be replaced with one with the same or bigger opening and the same type of hinges (LABC). |
| Safety glass | Glass within 800mm of the floor is a critical location (LABC), so low panes need safety glass. |
| Sign-off | In England and Wales, a FENSA or CERTASS registered installer self-certifies; otherwise you apply to building control. FENSA's remit does not cover Scotland. |
Check a registration yourself on the FENSA installer search or the Certified Competent search for CERTASS before the survey.
Before you sign
How to compare flush casement quotes
Compare flush casement quotes window by window on the same specification, not on the total. The Energy Saving Trust recommends getting quotes from at least three installers. Check that each quote lists:
- the opening plan and pane layout of every window;
- the frame material, colour inside and out, and the named profile system;
- the frame and sash sightlines in millimetres;
- the U-value or energy band of each window;
- the trickle vents and escape windows, room by room;
- the guarantee, who backs it, and the scheme that signs the job off.
Our guide on how to compare double glazing quotes shows what a full quote lists.
If you sign at home, you usually have at least 14 days to cancel, but made-to-measure windows can be an exception, so check the contract before you sign: see the double glazing cooling off period.
Compare flush casement quotesFree, no obligation
FAQ
Flush casement windows: common questions
Who will contact me after I ask for quotes?
A short call confirms the job first. Local installers who cover your postcode then contact you to book a survey and send a written quote.
What is the difference between flush casement and standard casement windows?
A flush casement's opening sash closes level with the frame, while a standard storm-proof casement's sash sits on top of the frame. Bassetlaw District Council notes that traditional casements were always set flush or recessed.
Are flush windows or casement windows better?
Neither suits every home. A flush casement matches the traditional look that council design guides describe, and in a conservation area or a listed building the council has the final say.
Do flush casement windows need planning permission?
Flush casement windows need consent in a listed building, and an Article 4 direction can restrict even a window of a similar design. In a Scottish conservation area, a front window that changes its opening method, panes or frame size means notifying the council first.
Get your flush casement quotes
Answer a few questions, take one call to confirm the job, then compare written quotes from local installers. To start from the homepage, compare double glazing quotes.
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Sources
Rules checked 8 October 2026.
- Bassetlaw District Council, Guidance Note: Traditional Casement Windows (January 2011)
- Historic England, repair or change windows in an older home and what permission might I need?
- Energy Saving Trust, energy efficient windows and doors
- Scottish Government, Planning Circular 1/2024, section 7 and building standards technical handbook 2022: domestic, section 6.2
- Approved Document L, Volume 1 (2021 edition incorporating 2023 amendments), Table 4.2
- LABC Front Door, fire escape windows, ventilation with windows and doors, safety glass and who can install windows and doors
- FENSA, about FENSA and find an installer; Certified Competent, installer search