A roof window can be fitted at any time of year. The roof does not care what month it is; what matters is how long the opening stays uncovered and what the weather does in that time. In winter the margin is thinner, the days are short, and an unexpected shower or a cold night catches out anyone who started without a fallback. The skill is in sequencing the work so that no opening ever meets weather the roof cannot shed.
This guide covers how we choose a day, what temporary cover goes on, the order in which the opening is cut, flashed and closed, and what happens inside once the window is in. The subject here is seasonal planning; total duration has its own page, our guide to how long a roof window takes to fit. For the whole service, start at roof windows and skylights.
Why winter is a sound time to book, and where it is harder
There are advantages to a winter fit. Roofers have more flexibility in the diary, the loft is easier to reach when it is not warm, and a new window that goes in before spring means the room is ready for the lighter months. If you have a leak around an old window, waiting for summer means another few months of wet weather on a failing flashing.
The hard parts are practical. Daylight is short, so there is less working time between the first light and the point where we want the roof closed. Wet slates and tiles are slippery, and roof work is paused when it is unsafe underfoot. Mortar, sealants and adhesives do not cure properly in the cold, so those parts of the job are timed for the warmer part of the day or avoided. And the margin for a delayed finish is smaller, because tomorrow's weather may not suit.
What we do about it
We plan around the forecast, not the calendar. A job is booked for a likely window of settled weather and rearranged if the forecast turns, and you are told when that happens. The roof is never opened on the strength of a hopeful guess. We would rather move a date than leave your ceiling exposed.
Choosing the day: what a weather window means for a roof window
A weather window is a stretch of dry, calm conditions long enough to open the roof, set the frame, flash it and close it again. For a single roof window in a pitched roof, that is a matter of hours. For a pair of windows or a loft conversion with several openings, we open and close one at a time, so only one opening is ever exposed.
The things we look at are rain, wind and temperature. Rain is obvious. Wind is the one people forget: a gusty day makes handling a large sheet of glazing or a metal flashing awkward, and a sheet of temporary cover can lift. Temperature affects sealants, foam and the tapes used round the frame, which have a stated working range, so a morning at freezing is often left until it warms.
The start of the day
We start when the roof is dry underfoot, and in winter that can mean a later start than you might expect. Frost on slate makes it unsafe, and moisture on the underlay prevents the tapes from sticking. Starting an hour late costs little; stripping a roof in poor light and rain costs a lot.
The decision to start is made on the day, on the roof, after checking the surface and the sky. A booked date is a plan, not a promise to work in any weather.
Access and scaffold
Scaffold brings its own winter considerations: boards that are dry enough to walk, ties that are secure, and a platform that gives room to work. Steep Stroud lanes and terraced hillsides can make the scaffold the longest part of the planning, and we work out access at the survey, not on the day.
Temporary cover: what keeps the roof dry while it is open
When a roof is opened, the loft below is exposed to anything that falls. The first protection is inside: dust sheets over what is stored in the loft, boards over the ceiling below the opening if the ceiling is finished, and a clear path through the loft so nothing is dragged across insulation.
The second is on the roof. A tarpaulin or heavy-duty temporary sheet is fixed over the opening and weighted or battened at the edges, with the upper edge tucked under the covering so that water runs over it and not behind. In winter the sheet is cut and waiting on the scaffold before any tile is lifted. A proper temporary cover is sized to be bigger than the opening, tucked beneath the course above, and held so a gust cannot get under it.
Closing the roof before the light goes
Whatever stage the work has reached, the roof is made weathertight before the crew leaves. If the frame is not yet fully flashed, the temporary cover goes back over it and the underlay is dressed down. The next morning begins by checking that nothing has moved. A roof opened in the morning and closed in the afternoon should never need to sit overnight under a sheet, but when the light goes early, a protected stop is part of the plan.
This is the same discipline we apply to a leaking roof: we make it safe first, then repair. It is how the work stays sound in uncertain weather.
The order of work: open, trim, set, flash, close
The order is the same as in summer, but each step is tighter. First the covering is taken up around the marked opening, tiles and slates numbered and stacked so they can go back in the same order. The battens are cut back and the underlay is slit. Then the rafters are trimmed: a pair of trimmers is fixed above and below the opening to carry the load of the cut rafters, and the opening is framed square.
The frame is then set into the opening and fixed to the trimmers, checked for level and squareness, and the underlay is folded up the frame sides so moisture reaching it is steered out across the covering. The flashing kit follows, from the bottom upwards, each piece lapping over the one beneath it. Last of all, the covering is laid back to the flashing and the sash is hung. Our guide to roof window flashings covers the kit for each covering.
Why speed is about sequence, not rush
The risk in winter is not a slow roofer; it is an out-of-order job. Opening a second opening before the first is closed, or cutting the rafters before the cover is ready, is how leaks start. We do each step to completion and photograph the result, so you can see the junction before it is hidden.
Stone slate and slate roofs take longer to open and close than machine-made tiles, because each unit is handled and the pegs or fixings are disturbed. That is why the weather window for those roofs is chosen more cautiously, a point relevant to Cotswold stone roofs in particular.
Cold-weather materials: sealants, foam, tapes and glazing
Products have a working range. Many sealants and tapes specify a minimum temperature for application, and some foams cure slowly or not at all in the cold. The data sheets give the figures, and we follow them. If it is too cold for a product to bond, the step waits or a different product is used.
Lead and aluminium flashing can be dressed in the cold, but lead is stiffer and needs care. A tool dragged across cold lead can split it where a warm sheet would bend. Cold glass is also less forgiving of knocks and of sudden temperature changes, so the glazed sash is kept out of direct sun on a frosty morning until it is hung, and it is stored upright and sheltered.
Why cold fixings need extra checks
Nails and screws go in the same, but the timber around them can be damp, and damp timber closes up around a fixing as it dries. We check the trimmers and the surrounding rafters for moisture on a survey, because a window fixed into wet timber can loosen later. Where the timber is wet, we find out why before we fix anything to it.
Condensation is also a winter question. A new window fitted in a damp loft can run with water in its first cold weeks, and the guide to types of rooflight covers which glazing and frame types suit each room, including those where damp is likely.
Finishing inside: lining, insulation and the damp problem
With the roof closed, the inside work begins. The opening is lined, the insulation is packed into the gap between the frame and the rafters, and the plasterboard or timber lining is fixed. In winter this is the stage people most want to hurry, because the room is cold and the loft is draughty. It is also the stage where mistakes show up later as condensation and mould.
Plaster and joint compounds need warmth and time to dry. A room that has been opened to the weather will take longer to dry out in cold, damp air, and trapped moisture in new plaster will show as staining or as a musty smell. Where we are only fitting the window and not plastering, we make the lining ready for your decorator and tell you what to leave to dry.
Insulation that meets the frame
The insulation around the frame is where heat loss and condensation start, as covered in our guide to condensation around roof windows. We pack it fully and make sure it runs up to the frame. Approved Document L caps a new roof window at 1.4 W/m2K, or Energy Rating Band B, and the installation has to support that figure, not undermine it.
For a home, insulation is zero-rated for VAT until 31 March 2027; the window and roof work are normally standard-rated, and the quote shows how VAT applies.
Booking in winter: what we need and what to expect
If you want a window fitted in the colder months, tell us early. Photographs of the roof from the ground, a note of the room below and any dates you cannot do help us plan. We survey and photograph your own roof, then send a written quote covering scaffold, window, flashing kit, labour and making good.
For typical figures, MyBuilder's 2026 pricing sits at about £350 to £600 to fit a standard roof window, plus scaffold near £500 if needed. Our guide to roof window costs goes through what drives the price up or down. Winter does not add a surcharge in the published ranges, but a job re-booked for weather may need the scaffold to stay up or go up twice, and the quote spells that out.
What you can do
Clear the loft area below the opening and move anything fragile. Tell us if the room below is in use. Make sure the route to the roof, whether a drive, a lane or a side passage, is clear for deliveries. And be ready for a rescheduled day. A date that moves for weather is a sign the plan is working.
Everything we fit sits under our written 10-year workmanship guarantee, and the site is cleared as we finish.