Misted rooflights in Maidstone
Moisture between the panes means the sealed unit has failed, and a cloth will not reach it. We survey first to see whether the glass, the frame or the whole rooflight needs replacing, then fit it to measure across Maidstone and mid-Kent.
- Free survey, fixed written quote
- 10-year workmanship guarantee
The long read
Misted rooflights: causes, replacements and what the new unit must meet
Cloudy glass that no cloth can reach comes from inside a sealed unit, and it tells you the unit has stopped doing its job. The fix depends on what has failed: sometimes only the glass, sometimes the frame, flashing or kerb as well, and a survey settles which. To start with your own window, send us a few photos.
Mist between the panes, and what it means
Wipe the glass on the room side with a dry cloth. If the haze moves, it was ordinary condensation, the film that settles on a cold pane above a shower or a boiling kettle. If the haze stays where it was, or you can see a cloudy film, beads of water or a faint tide-line of dried marks that no cloth can reach, the moisture sits inside the cavity between the panes. That is a misted rooflight.
A double-glazed unit is two panes of glass held apart by a spacer bar that runs round the edge, with sealant bonded to both panes. The gap is made dry, and often filled with gas, because a dry gap insulates. When the edge seal lets air and moisture in, the water vapour condenses on the cooler pane and stays there, because the cavity has no way to dry itself out.
Checks you can make from the room
Wipe the inside face, look at the glass edges for a tide-line, and note whether the cloudiness is worse at dawn than at noon. Send us two or three photos of the glass and the whole window with the date you first noticed it.
How the moisture gets in
The edge seal is the weak point of any sealed unit, and a rooflight puts it under more strain than a wall window. The glass is tilted towards the sky, so it takes the full sun on a July afternoon and a hard frost on a January night. Each swing makes the sealant expand and shrink. Water that settles against the lower edge of the glazing, in a channel that drains badly, can sit on the seal for days after rain. A knock from a ladder, a branch or a hailstorm can crack an edge, and a frame that has moved a little can pull at the bond.
The first sign is often patchy. A unit may be clear on a warm dry afternoon, then cloud over on a cold morning, and later stay cloudy all year. By then the seal has gone for good, which is why our guide to why rooflights mist up between the panes puts the fault down to the unit itself. A short answer on whether misted rooflight glass can be cleared covers the drilling-and-drying fixes some people try first.
Every kind of rooflight can do it
Any product built from sealed double-glazed units can mist. That includes a pitched roof window in a loft bedroom, a flat rooflight on a kerb over a hallway, the glazed faces of a roof lantern on an extension, and the glass roof panels of an orangery or conservatory. A VELUX roof window fails in the same way as a unit from any other manufacturer's range, since the sealed glass inside is built the same way.
What it does to the room
A misted pane scatters daylight and blurs the view of sky, so a room that used to be bright can feel flat and grey. The insulating gap has lost its dry, gas-filled state too, so the glass loses more heat on a winter night and the pane feels colder to the touch. On a landing or in a bathroom that depends on a single rooflight for its daylight, the effect is easy to notice. A stain that appears alongside the mist is a separate matter, and the next chapter takes it apart.
Misted, damp or leaking?
A cloudy pane and a brown ring on the reveal are separate faults that sometimes turn up on the same window. Three different kinds of wet get blamed on a rooflight, and each has a different cure.
Telling the three apart
- Wipe the room side Haze that moves under a cloth is condensation on the surface.
- Check between the panes A film, droplets or tide-line you cannot reach is a failed seal.
- Study the lining and reveal Stains, soft timber or lifting paint point to water coming in from outside.
- Watch a wet day Note whether drips show during heavy rain or only after it, and where on the frame they start.
Condensation on the room face
Warm, humid air meets a cold surface and leaves a film of water. It forms on the inside of the glass or the frame, wipes away, and returns after the next shower. It points to humidity, ventilation or a cold frame, and a new sealed unit will not change that. An en suite under the roof, with a window in the slope and a fan that is rarely switched on, is the usual setting.
Moisture between the panes
This is the failed seal described earlier. It is inside the sealed unit, it never wipes off, and it is a fault of the glass itself. Replacing the sealed unit clears it. Our answer to whether a misted skylight means it is leaking goes through the signs that separate the two.
Water getting past the flashing or the kerb
A drip in heavy rain, a dark patch on the timber lining, plaster that has blown at the head of the opening or a tide-line that grows after a storm all point to water entering from outside. On a pitched roof that means the flashing, the soakers or the tiles and slates around the frame. On a flat roof it means the upstand, the roof covering dressed up it, or a cracked fillet. None of these is a glass problem, and a new sealed unit dropped into the old frame will leave the entry point as it was.
When two faults arrive together
A unit with a failed seal has often stood on the roof long enough for its surroundings to have aged too. The sealant is the same age as the flashing, and both have lived through the same winters. We look for water tracks on the lining, soft or darkened timber at the sill and fine cracks where the covering meets the frame, because that decides whether the job is a sealed-unit swap or a whole new rooflight. If the unit is leaking as well as misted, the roof gets looked at from outside first, and the glass second.
Why we go up on the roof
From the room you see the glass and the lining. From the roof we see the flashings, the kerb, the covering, the gutters that feed the unit and any moss, debris or standing water that has gathered above it. On a low flat roof we can often reach all of it from a ladder. On a steep slope or a tall house we agree access with you before we arrive, which may mean towers or scaffold, and we explain that at the survey.
Sealed unit only, or the whole rooflight?
The sealed unit is the part that has failed, but it is not always the only part worth changing. The frame around it, the flashing outside it and the kerb or lining it sits in all age at their own rate, and the decision turns on their condition.
| Finding | Usually points to | What we would price |
|---|---|---|
| Frame straight, seals and beads sound, mist only between the panes | A glass-only swap | A new sealed unit made to measure |
| Soft or stained timber at the sill, hardened gaskets, bowed frame | A whole roof window | New unit, flashing and finished lining |
| Cracked upstand or roof covering lifting at the kerb | A whole rooflight with kerb work | New rooflight and the flat roof detail around it |
| Yellowed single-skin plastic dome with crazing | A whole rooflight | Glass unit on a checked kerb |
When a new sealed unit is enough
If the frame is straight, the glazing beads and gaskets are sound, the timber or the aluminium is free of rot and corrosion, and the flashing is dry and tight, a new sealed unit into the existing frame is a sensible job. The replacement is made to measure: its outside dimensions, overall thickness and the build-up of its panes are taken from the old one so that it sits in the frame the way the original did. A new unit also lets you improve the glass, for instance with a low-emissivity coating or a laminated inner pane, within what the frame can carry.
When the whole unit should go
A frame with a soft sill, a bowed head, a corroded corner or gaskets that have hardened gives a new sealed unit a poor home. The same holds if the flashing has failed, if the old unit was a one-piece type built so that its glass cannot be swapped, or if it is too small for the daylight the room now needs. A flat rooflight on a cracked kerb is another case: the new glass would sit on the fault. In these cases we price a new roof window or rooflight, with fresh flashings and a finished lining. Our guide to new glass or a whole new unit works through the decision in more depth, and the rooflight replacement cost guide lists what shifts the figure.
Reading the size of an old unit
On a VELUX roof window a code like MK04 stands for the size: letters for the width, digits for the height. If your window has a code we use it as a starting point, then we measure the opening and the frame ourselves, because the code alone does not tell us how the glass has been built up or how the flashing sits. Windows from older ranges and other makers may have no code to read, so the dimensions come from the survey tape. Our note on swapping an old VELUX window goes into the like-for-like route.
When the old frame limits the new glass
A frame was designed around a particular thickness of glass. A modern low-e unit with warm-edge spacers can be slimmer or heavier than the glass it replaces, and the frame may not take it. We check the rebate depth and the fixings at survey and tell you if the new glass would have to stay close to the original specification. If the limit is the frame, the better answer may be a whole roof window, built to current energy standards from the start.
Replacing a failed unit: how the installation works
The sealed units are made after the survey, to the dimensions taken there, so the job runs across two visits: one to look and measure, one to fit. Between them the new glass is made, and any lining or flashing materials are ordered if the survey called for them.
Myth
A misted unit can be swapped entirely from inside the room, so nobody needs to go on the roof.
Fact
The flashings, kerb and covering that keep the rain out are on the outside, so the survey and the fitting both cover the roof side of the window as well as the room.
Replacing old or failed glass on a pitched roof
On a pitched roof the work usually begins from the roof side. We protect the floor and furniture below, open the glazing retainers, lift the old unit out and check the rebate and the frame underneath. If they are sound, the new unit goes in with fresh gaskets and seals, the retainers go back, and the glass is cleaned inside and out. A flat rooflight on a kerb follows the same pattern, with the added check that the kerb and the covering dressed up it are dry and firm before the glass goes back.
Whole roof windows
For a whole unit we strip the flashing and lift the old frame out of the opening. We look at the rafters and battens around the hole, because a leak that has run for a while can have marked the timber, and then we fit the new window to the roof structure. The flashings are dressed into whatever covering your roof has, whether plain tiles, concrete tiles or slate. Inside, the lining is boarded, insulated where needed and finished ready for your decorator. A pitched window in a loft bedroom or a kitchen lean-to takes about the same sequence; the covering is what sets how much care is needed at the edges.
Flat roofs and lanterns
On a flat roof, the glass sits on an upstand or kerb, and the roof covering is the waterproofing. We check the upstand for height, insulation and condition, and we rebuild it if the old one has softened or cracked. A misted pane on a roof lantern often means one or two glazed units have gone while the rest are sound, and the lantern frame can sometimes take new panes. On a newer extension the frame may be sound enough to keep.
Orangery and conservatory roofs
Sealed glass panels in a conservatory or orangery roof mist just as a rooflight does, and they are swapped the same way where the glazing bars are sound. A leaking bar cap or a sagging ridge is a different problem and gets its own line on the quote. If the whole roof has reached the end of its life, replacing it with a solid insulated roof and a central lantern can leave you a better-insulated room with a bright centre.
Leaving the roof closed
Before we leave a roof, the opening is closed and weathertight, the old units and offcuts go with us, and the room below is cleaned. Where the opening has to be left for a second visit, for example when a lining needs to dry, we explain what is happening beforehand.
What moves the price of a swap
- Glass-only or whole unitThe condition of the frame and flashing decides which.
- Size and glass build-upBigger panes and extra coatings or laminates cost more to make.
- Roof coveringTiles, slate, felt or single-ply each need different flashing detail.
- AccessPitch, height and a tight garden decide whether ladders, towers or scaffold are needed.
Energy limits, safe glass and paperwork
Energy rules apply to a replacement roof window or rooflight even though no new hole is cut in the roof. Approved Document L sets a limit for new and replacement glazing in an existing home, and the figure depends on the product. A replacement roof window takes the window limit of 1.4 W/m²K, or a Window Energy Rating in band B at the least. A rooflight or roof lantern takes 2.2 W/m²K. The measure is the whole unit with its frame, so a good pane in a poor frame can still fail it. Our section on energy-efficient rooflights goes further into glass, coatings and U-values.
| Product | Part L limit | Point to check |
|---|---|---|
| Roof window in a pitched roof | 1.4 W/m²K, or WER band B minimum | Opening size if it is an escape window |
| Rooflight on a kerb | 2.2 W/m²K | Kerb height and insulation |
| Roof lantern | 2.2 W/m²K | Frame strength for the glass build-up |
Frames, glass and what they do for performance
Aluminium frames are slim, and with a thermal break they hold heat well. uPVC frames cost less and are bulkier, and a white uPVC frame can match existing conservatory frames. Timber-lined roof windows suit a loft room that is finished in wood or paint. Double glazing is the starting specification for every unit we fit, with a low-emissivity coating and a warm-edge spacer. Insulation around the frame and flashing matters as much as the glass, because cold edges invite fresh condensation at the frame.
Safety, security and solar control
A laminated inner pane holds together if it cracks, so shards do not fall into the room, which matters over a bed or a stair. Laminated glass also resists forced entry, which is worth having over a flat roof that someone could climb onto. For a south- or west-facing room, a solar control coating limits summer heat while letting daylight in.
Escape windows in rooms in the roof
Where a chalet bedroom or a bungalow loft room uses its roof window as the emergency escape, the opening has set minimums: 0.33 m² of clear area, 450 mm wide, 450 mm high, with its lower edge 1,100 mm or less above the floor, and a catch that holds the sash open by itself. If your window serves a room like that, we keep to those figures when the replacement goes in. Where the house has two full storeys, a loft conversion normally relies on a protected route down the stairs and not on the window.
Planning and Building Control
Swapping a unit like for like in the existing opening normally leaves the roof outline as it was. If the new one would stand higher or project further than the old one, or if your house is listed, in a flat, or subject to an Article 4 direction, the position changes, and our skylight planning guide covers each case. At the survey we check whether the work is notifiable and handle the Building Control notification where it is. The Building Regulations guide sets out the rules in full.
Clear glass and the daylight it returns
A loft stair landing is the sort of space where a rooflight does all the work. There is no outside wall to hang a window in, the doors off it are usually closed, and a single pane in the slope is the whole daylight supply. When that pane has gone cloudy, the landing goes dull, and the lights go on at midday.
Parts of a sealed unit
- Spacer bar
- The strip round the edge that holds the panes apart and forms the cavity.
- Edge seal
- The sealant bonding the panes and spacer together; where moisture gets in once it fails.
- Low-e coating
- A thin coating on one pane that reflects heat back into the room.
- Laminated pane
- Two sheets of glass bonded to a clear interlayer so a crack stays held together.
- Flashing
- The metal or membrane that carries rain over the edge of the frame onto the roof covering.
What changes with a clear unit
A new sealed unit sends daylight into the room at the angle it was designed for, and the view of sky returns. Bedrooms in the roof feel taller when they have clear glass overhead, and a small loft study gets the even, shadow-free light that suits a desk. A bungalow hall with a sun tunnel or a small roof window above it can read as a lit room again. Where a lantern crowns an extension, the middle of the plan gets light from above and the walls do less of the work.
Brightness through the day
Overhead glass sees more of the sky than a wall window does, and the part of the sky straight above is brighter than the part near the horizon on a grey day. That is why a rooflight keeps a room usable on a dull afternoon. A misted unit gives some of that back as haze. A clear one gives it back as light you can read by, and the glass with a low-emissivity coating still lets daylight through while holding heat in.
Where the benefit shows most
A utility room with no window, a garage conversion whose side walls are shared, an en suite in the eaves and a flat-roofed garden room with doors on only one side all rely on the roof. Even a room with a normal window may have a dark corner far from it that a rooflight reaches. In the opposite situation, a south-facing loft can overheat under a clear pane, and we raise solar control glass at the survey.
Wellbeing and the way a room is used
A view of moving cloud and changing light changes how a room feels in a way a ceiling fitting does not. Daylight shows true colours for painting or cooking, and it cuts the number of lamps that run through the day. A clean pane keeps that going. For the wider picture on keeping units performing, our short answer on how long rooflights last covers what wears out first.
Homes we cover and how to book a survey
We replace misted units and failed rooflights in homes across Maidstone and the towns and villages out to roughly 30 miles by road from the town. The houses vary from Victorian terraces with a single window in the back slope to 1990s estate houses with converted lofts, bungalows with a hall rooflight and modern extensions with a flat roof and lantern.
Areas covered around Maidstone
Closest to town you will find us in Bearsted, Coxheath, Aylesford and Larkfield, and out towards Kings Hill and West Malling. Towards the Medway towns we cover Chatham, Rochester and Gillingham. To the south and west we reach Tonbridge and Royal Tunbridge Wells, and across to Staplehurst, Marden, Lenham and Charing. Each council has its own planning team, and we check the records for your address before quoting.
Booking the survey
The survey is free and happens at your home. We look at the glass, the frame, the lining, the flashing and the kerb, go up on the roof where it is safe to do so, and measure the unit and the opening. We also ask how the room is used, because that affects the choice of glass.
You then receive a fixed written quote. It names the sealed unit or the whole rooflight, its size, frame, colour and glass specification, any flashing or lining work, access, and the Building Control notification where one applies. If the survey finds something you ought to know first, such as roofing felt that has perished around the opening, it is listed on the quote separately. Our work carries a 10-year workmanship guarantee in writing.
Getting in touch
Use the quote form, or WhatsApp us on 07880 284133. Email works too: info@orchardskylightsmaidstone.co.uk. A size code, a make on the frame or a note of when the mist first showed all help us bring the right equipment.
What the written quote names
- The unitSealed unit or whole rooflight, with size, frame colour and glass specification.
- Roof work around itFlashings, kerb or upstand, and the covering dressed into them.
- InsideLining, reveals and the finish left ready for decorating.
- Access and paperworkLadders, towers or scaffold, and the Building Control notification where required.
Misted rooflight replacement guides and answers
Cloudy glass: what next?
Mine only clouds over on cold mornings. Has the seal really gone?
Mist that thins in warm weather is still inside the cavity, which means moisture has already got past the edge seal. At that stage the unit usually clears and clouds on a cycle for a while, then stays cloudy. A photo of the glass taken on a cold morning helps us at the survey.
What happens to the room while the old unit is out?
We lay sheets over the floor and furniture before the unit is lifted, and the opening is closed and weathertight by the time we leave the roof. A glass-only swap on a single window is usually an uncluttered job inside, with the mess limited to the area below the window.
My roof window is an old VELUX with a code starting MK. How do you match it?
Read the letters as the width and the digits as the height. We use it as a starting point and then measure the frame and opening ourselves, since the glass build-up and the flashing affect what will fit.
Can a new sealed unit be better than the one it replaces?
It often can, within what the frame will carry. A low-emissivity coating, a warm-edge spacer, a laminated inner pane or solar control glass can all be specified on the replacement, and if the frame cannot take them, a whole unit is the better route.
The glass roof of our conservatory has gone cloudy between the panes. Is that the same fault?
If the roof is made of sealed glass panels, it is the same failed-seal fault and the panels are swapped like rooflight units, provided the glazing bars are sound. Twin-wall polycarbonate is a different build and needs looking at separately.
What should I send to get a survey booked?
Two or three photos of the misted glass, the whole window from inside and the roof from the garden, plus your postcode, are enough to start. Send them by WhatsApp on 07880 284133 or use the quote form.
Book your free survey
Tell us about the room that stays dark. We come out, look at the room and the roof, then send a fixed written quote.
Or on 07880 284133, or call 01622 277162
No obligation. We survey before we price.