Can rooflights be fitted in winter?

Cold on its own is not the obstacle

People picture winter installation as a cold problem, and it very rarely is. A roof is opened, the structure is trimmed, the unit is set down and weathered in, and the covering is dressed back around it. None of those operations care much about air temperature in itself. What they care about is whether the roof surface is safe to stand on, whether water is arriving while the opening is exposed, and whether the wind will allow anybody to handle a large piece of glass at height.

There is also a plain reason winter is when people most want this work done. The months when a dark room is at its worst are the months being complained about, and a rooflight installed in February delivers light through the rest of the spring that one installed in July does not. Enquiries do not arrive evenly through the year. They arrive from people sitting in the problem.

What actually stops a roof being opened

Four things, and only one of them is really about temperature.

Driving rain. Water gets into an open roof faster than an open roof can be closed. Steady rain on a covered, weathered unit is unremarkable. Rain during the stage when the structure is exposed is another matter entirely.

Wind. The hardest limit of the four. Sheet material, a scaffold platform and a glazed unit being lifted into position in a gale is not a judgement call, and it is not one we quietly make to keep a booking.

Ice on the slope. Frost on a pitched roof is a safety matter for the people standing on it, and no amount of care makes a frozen slate slope acceptable to work off. It usually clears as the morning goes on, which makes a frosty start a delayed start rather than a cancelled one.

A forecast that turns. Winter weather changes faster than summer weather, and a morning that looks workable can close in. The decision to open a roof is taken against what is coming, not against what happens to be overhead.

An open roof is never left overnight

This is the rule that matters most to the person living in the house, and it does not vary with the season. An opening is formed, made weathertight and closed before anybody leaves site. The house is dry and secure when the van goes, rather than sheeted over and hoped about until the morning.

That discipline is exactly why winter working is possible at all. Because the exposure is short and deliberate rather than spread across the job, it can be placed inside a window of suitable conditions instead of taking whatever the sky offers over a longer stretch. Everything achievable without opening the roof happens first: access up, materials on site, protection laid inside, the room below cleared. The opening comes last, when conditions are right for it.

If an installer is willing to leave a roof open under a tarpaulin because the light went, that tells you something about their method rather than something about the season.

Short days change the shape of the working day

Daylight is a genuine constraint in a way that cold is not. Roof work needs light to be done safely and accurately, and there is simply less of it available through the winter. A floodlight on a slope is not a substitute for daylight.

What that means in practice is a tighter window in which the roof can be opened and closed with margin to spare. Starts are earlier relative to first light, the sequence is planned so the exposed stage falls in the middle of the available light rather than at the end of it, and internal work such as lining and making good is placed where losing the daylight does not matter.

It also means we are more conservative about what gets committed to a single visit in winter than we would be in high summer. That is planning rather than caution, and it is one of the reasons winter work goes smoothly when it has been thought about in advance rather than promised optimistically.

Materials that behave differently in the cold

Some of what goes into an installation is temperature sensitive, and that is planned for rather than discovered. Adhesives, sealants, primers and cold-applied flat roof systems all have conditions in which their manufacturers warrant them and conditions in which they do not. Those are the manufacturer’s limits rather than a convenient excuse of ours, and working outside them produces a detail that looks correct on the day and behaves badly later.

The answers are practical. Materials are stored and brought to the roof warm rather than pulled off a frozen van. Products are chosen for the conditions in which they will actually be applied, which sometimes means a different system in January from the one that would be specified in June. Surfaces are checked for frost and moisture before anything is bonded to them, because a bond made to a cold damp surface is not a bond.

Lead, by contrast, works perfectly well in the cold and always has. Much of what makes a pitched roof weathertight is mechanical rather than chemical, which is part of why pitched work is less weather sensitive in winter than flat roof work is.

A winter date needs more slack, and still beats waiting

The honest point is that a winter booking is more likely to move than a summer one. More conditions are unsuitable, forecasts turn faster, and scaffold diaries are affected by the same weather everybody else is working around. We would rather say that at the enquiry than take a deposit against a date we privately doubt. Our Carterton page sets out how a programme is planned around a fixed deadline, and the Chipping Norton page covers what cold does to the specification itself.

What follows is slack built in at the front of the programme rather than pressure applied at the back of it. Survey, specification and ordering all happen indoors and are unaffected by the weather. It is only the opening itself that is weather dependent, and that is a small part of the whole.

Which is why waiting for spring is usually unnecessary. We install new rooflights and replacements across Oxford and up to twenty five miles by road, we handle the Building Control notification, and our workmanship carries a ten-year guarantee.