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What changes the cost of resealing a window?
A reseal quote changes with whether you mean a draught at the frame, a seal on the sash, or mist between the panes of a double-glazed unit. This guide does not print a price, and a new glass unit is a different job from a bead of sealant.
Last reviewed:What people mean by reseal
The word covers at least three complaints, and a quote that uses only the word is hard to trust.
- Air at the edge. You feel a draught on a windy day, often at the meeting rail of a sash, at a trickle vent, or where the frame meets the wall. The glass can be clear. The job may be seals, staff beads, or mastic. It may also be a frame that has moved.
- Moisture between the panes. The view is foggy and you cannot wipe it off from either room side or the outside face. People call that a failed unit. This guide does not print a lifespan for a sealed unit, and it does not tell you the fog has only one cause. It tells you to describe the fog, not to call it a draught.
- A replacement unit or a replacement window. The glazier takes the glass out, or the whole frame. That is the point where building regulations, on the pages below, start to talk about replacement glazing. It is no longer a tube of sealant.
A sash in Crewe, a casement in Nantwich or a patio door in Sandbach can draught at the frame, fog between the panes, or need a new unit. Name the symptom, on a Cheshire window or one further away. Anyone in the UK can post the job. This guide prints no price for sealant, for a unit, or for a window.
Replacing a sill is the rotten shelf or the outside weathering. New windows is the whole unit. A single pane is a different scheduled page if the complaint is one piece of glass. Stay here if the question is the seal.
What the quote should itemise
| Line | What the writing should say | What a thin quote hides |
|---|---|---|
| The symptom | Draught, fog between panes, or both, as you described it | "Reseal windows" |
| Which windows | Room and floor, counted | "The house" |
| What they will do | Mastic, new draught seals, new unit, or new window | A method you cannot picture |
| Glass | Stays, or a glazing unit is replaced. A replaced unit is on the tell-building-control list [S1] | Glass out with no paperwork |
| Opening | Unchanged, or a new window with the escape potential kept [S2] | A smaller opener that nobody mentioned |
| Frame | Accepted as sound, or a separate repair | Sealant on a rotten frame |
| Sill | In this quote or not | A sill discovered on the day |
| Inside making good | Beads, plaster, decoration | Scars round the reveal |
| Access | Ground floor, or how they reach an upper window | A ladder assumed |
| Certificate | Only if a unit or a window is replaced, and which scheme [S3] | A certificate promised for a bead of mastic |
| VAT | Included or not. The registration threshold is £90,000 [S4] | Added later |
Draughts, without a product lecture
A draught is a gap. The useful quote says where the gap is.
- Between the sash and the frame: the draught seals or the staff beads may be the line.
- Between the frame and the wall: mastic on the outside, or a gap in the plaster inside. Sealant on top of a wet, rotten frame will not hold. Ask them to say the frame is sound, or to price the frame.
- At a trickle vent: the vent may be open, blocked, or broken. Closing every vent to stop a draught can be the wrong fix in a room that needs air. The Planning Portal, writing about replacement glazing, says the regulations apply to thermal performance and also to air supply and ventilation [S2]. This guide does not turn that sentence into a rule for a bead of mastic. It does say you should not instruct someone to block every vent without asking what the room is supposed to do for air.
Do not climb to inspect an upper sash. If you can feel the draught from the floor, describe it from the floor.
Fog between the panes
Say what you can see: "I cannot wipe the mist off either face." That sentence is enough for a glazier to know you are not talking about condensation on the room side, which is moisture on the surface you can touch. Room-side condensation is a different conversation, about the room and the glass temperature, and this guide does not explain the physics of it. It asks you not to label it a failed unit if you can wipe it away.
If the mist is between the panes, the quote is often a new sealed unit in the existing frame. GOV.UK's exception is plain: most repairs and maintenance are examples of work you do not need to tell a building control body about, except replacements of combustion appliances, oil tanks, electrical fuse boxes or glazing units, which do need to be told [S1]. A replacement glazing unit is in that exception. Since 1 April 2002 the Planning Portal says building regulations have applied to all replacement glazing [S2].
So a new unit is not "just a repair" on those pages. Ask who tells building control, or which competent person scheme the installer is on. The Planning Portal says a scheme installer can do replacement glazing without you involving local authority building control, and then gives you a certificate, and that otherwise the building control body checks the work [S2]. GOV.UK says a scheme installer should provide a certificate of compliance within 30 days [S1].
FENSA says it is a government-authorised scheme that monitors building regulation compliance for replacement windows and doors [S3]. Ask if a new unit in an existing frame is something they will certificate, or if the frame is staying and only the glass changes. Do not let a homepage stand in for the fitter's answer.
GOV.UK sets out building regulations approval. HSE explains work at height in its questions. GOV.UK: building regulations approval. QuoteZila is not affiliated with this organisation.
When the job grows
Sealant that will not stick because the frame is soft is a frame or sill job. Price it separately. Our glaziers page is the trade for the glass. Joiners and carpenters are the trades if the timber is the fault and the glass is fine.
An upper window is above floor level. HSE says you are working at height if you work above ground or floor level, where a fall could cause personal injury if precautions were not taken [S5]. The quote should say how they will reach it. This guide does not set out a climb. HSE: work at height. QuoteZila is not affiliated with this organisation.
If the whole frame is to be replaced, you have left resealing. The escape rule on a replaced window is the Planning Portal's: the opening should provide at least the same potential for escape as the one it replaces [S2]. Put that in the quote as a sentence the fitter owns.
How to compare the quotes
Citizens Advice says to try to get written quotes from at least three traders. A quote is a fixed price and an estimate is a rough guess [S6]. Some traders charge for quotes, so ask about this first [S6]. If the work will take a long time and a deposit cannot be avoided, push it down, do not agree to more than 25%, and get a receipt [S6].
Compare draught repairs with draught repairs, and new units with new units. A business must register for VAT if its taxable turnover for the last 12 months goes over £90,000 [S4]. That threshold is not a window price. Ask whether VAT is inside the figure you were given.
Jobs you might post
These are examples, not taken from real job posts.
- "Two sash windows in the front bedroom draught at the meeting rail. Glass is clear. Please quote new draught seals only, and say if the frames are too soft for that."
- "Kitchen window is misty between the panes. I cannot wipe it off. Please quote a new sealed unit in the existing frame, and say whether building control or a scheme certificate applies. Do not quote a whole new window unless the frame is unsound."
- "Lounge casement, draught between the frame and the outside wall. Please quote the mastic only if the frame is sound. The sill is a separate question."
Posting the windows
A photo of the whole window and a close photo of the mist, or of the gap, taken from inside, is enough. Up to five matched local businesses can send a quote [QZ2]. QuoteZila is free for customers and local businesses [QZ1].
Honest status: QuoteZila is new. We're starting in Cheshire, beginning with Crewe, Nantwich and Sandbach, and growing area by area. Anyone in the UK can still post a job or register a business. How fast you get quotes depends on how many local businesses have joined near you. Businesses can register and receive jobs straight away. We don't check insurance, qualifications or registrations, so please check these yourself before you hire.
Posting a job is not open yet
Questions about resealing
How much does it cost to reseal a window?
This guide does not print a figure. Sealant around a frame, new draught seals on a sash, and a replacement double-glazed unit are different quotes. Ask the glazier which of those they have priced before you compare the totals.
What is the difference between a draught and mist in the glass?
A draught is air you feel at the frame, the sash or the sill. Mist or moisture that sits between the panes is inside the sealed unit. Tell the glazier which you can see or feel. This guide does not claim a cause for every misty pane. It does say the two complaints should not share one line on a quote.
Is a new glass unit a repair or a replacement?
GOV.UK lists most repairs, replacements and maintenance as work you do not need to tell a building control body about, except replacements of combustion appliances, oil tanks, electrical fuse boxes or glazing units, which do. Since 1 April 2002, the Planning Portal says, building regulations have applied to all replacement glazing. A bead of sealant on a frame that stays is not that replacement. If the unit itself is replaced, treat it as the glazing they name.
Will resealing shrink the escape window?
Sealant around a frame should not change the opening. If the quote becomes a new window, the Planning Portal says that when any window is replaced, the opening should provide at least the same potential for escape as the window it replaces. Ask the fitter to confirm the opening size is unchanged if they are only sealing, and to say so if they are replacing the window.
Does a FENSA certificate cover a tube of sealant?
FENSA says it monitors building regulation compliance for replacement windows and doors, and that a FENSA certificate comes with a FENSA installer. That is about replacement windows and doors. This guide does not stretch it to a draught bead on a window that is staying. If the glass unit or the window is being replaced, ask whether that scheme is the one they will use.
The sill is rotten as well. Is that this job?
Not unless the quote says so. A soft board or an outside stone sill is a sill quote. A whole new window is a window quote. Keep the reseal as its own line so you can see what you are buying.
Does QuoteZila check glaziers?
No. We don't check insurance, qualifications or registrations, so please check these yourself before you hire. You can report a quote or a business from your job page.
This page is general information, not professional or legal advice. QuoteZila does not check Gas Safe, WaterSafe, NFRC, NICEIC or other registrations against the register on your behalf: look them up yourself.
Part of Cost guides. All services
Related trades
Related pages
- Triple Glazed Windows: What Changes the Price. What changes the price of triple glazed windows: frame material, size and style, glass spec, fitting, making good, building regulations, FENSA and VAT.
- UPVC Bay Windows: What a Quote Should Name. A UPVC bay quote in Cheshire should name the projection, the corner posts and whether a new bay counts as an extension. Ask who carries the wall above.
Sources
- QZ1: QuoteZila product fact. QuoteZila home and FAQ copy.
- QZ2: QuoteZila product fact. QuoteZila FAQ How does getting quotes work.
- S1: Building work, replacements and repairs to your home, GOV.UK. Accessed 2026-10-29. https://www.gov.uk/government/publications/building-work-replacements-and-repairs-to-your-home/building-work-replacements-and-repairs-to-your-home
- S2: Building regulations: doors and windows, Planning Portal. Accessed 2026-10-29. https://www.planningportal.co.uk/permission/common-projects/doors-and-windows/building-regulations/
- S3: FENSA, FENSA. Accessed 2026-10-29. https://www.fensa.org.uk/
- S4: Register for VAT, GOV.UK. Accessed 2026-10-29. https://www.gov.uk/register-for-vat
- S5: Work at height: frequently asked questions, HSE. Accessed 2026-10-29. https://www.hse.gov.uk/work-at-height/faqs.htm
- S6: Before you get building work done, Citizens Advice. Accessed 2026-10-29. https://www.citizensadvice.org.uk/consumer/getting-home-improvements-done/before-you-get-building-work-done/