The short answer
There is no bad season. A skylight can be installed in any month, and the work is planned around the weather rather than cancelled by it. Late spring to early autumn gives the longest dry days and the easiest drying conditions. Winter jobs go in too, with shorter working days and a tighter watch on the forecast. Book for when you want the light, not for the calendar.
What the season really changes on the day
The season does not change what a good installation is. It changes how much of each day is usable, and how carefully the opening is covered while the old unit is out.
Two things set the pace: daylight and dry surfaces. Daylight decides how long the crew can work on the roof, since nobody should be on tiles or a flat deck in poor light. Dry surfaces decide when sealants, adhesives and flat-roof membranes can be laid. Both are easy in July and more demanding in January.
The cover matters too. Once a unit is out, there is a hole in your roof until the new one is in and sealed. In every season we plan the job so the opening is never left uncovered at the end of a working day. A full replacement is often finished between morning and mid-afternoon, and a larger lantern may take longer. Our page on how long a new rooflight takes goes through the stages.
Summer, when the work is easiest
Long days, dry decks and warm materials make summer the simplest season to install in. It is the most forgiving, not the only choice.
Sealants and adhesives cure more predictably when it is warm and dry. A flat-roof rooflight needs its upstand built and its roof covering dressed up to the frame, and that finish behaves best on a dry deck. A roof lantern is heavy glass and aluminium that has to be lifted and set square, and a long dry spell helps with that.
The trade-offs are plain. Summer is a popular time to book work on the house, so the diary can fill sooner. Very hot roofs are uncomfortable to work on, so some jobs start early in the day. And a loft bedroom can be warm with the old unit out, so it helps to clear the room.
Autumn and spring, the middle ground
These months are mixed, with the weather changing inside a single week. That is fine, provided the plan allows for it.
A run of showers does not stop a job, because a roof window can be swapped quickly and closed in. What it does is influence the order of work. We choose a day with a clear window for the opening-up and the weathering. Check the page on installing in the rain for what that looks like in practice.
Autumn has one real advantage for our kind of work. Rain is the best test of a rooflight's sound. If you are choosing glass for a loft or a kitchen, a wet week lets you hear what the current unit does in the weather you actually get. We listen for that at the survey, and it goes into the written quiet spec. A dry summer survey is still fine, but we then judge by the build of the roof rather than by the sound on the day.
Winter, and what we do differently
Winter installation is normal. The working day is short, and in southern England midwinter daylight is only around eight hours, so we plan tighter.
| Winter issue | What we plan for |
|---|---|
| Short daylight | Start at first light, finish weathering early |
| Wet or frosty decks | Wait for a dry, frost-free window |
| Wind on a lantern lift | Pick a calm day for the crane or lift |
| Cold room below | Keep the opening covered, work fast |
A flat-roof job is the one most affected, because a wet or frozen deck is not a good base for a roof covering. Where the weather blocks that stage, we wait for a dry day rather than push on. A slope-mounted roof window is less fussy. It goes in over the existing tiles and can be done in a shorter window.
Winter also has a reward. Low sun comes in deep, so a new rooflight shows you at once how much light it delivers in the darkest months. It is a fair test of a position. You can read about where to position a skylight before you choose.
Picking your month
Start with the reason you want the rooflight, then work back to a window of time. The best month is the one that solves your problem.
If the problem is a failing unit, do not wait for summer. A unit that lets in cold, mist or noise is costing you comfort every day, and replacement goes ahead safely in any season. The signs a rooflight has failed will help you judge whether it is time.
If you are building an extension, the rooflight follows the roof, so the roof programme sets your month. Lanterns and flat rooflights are fitted once the structure is ready, and our flat roof rooflight installation and roof lantern installation pages explain the sequence.
If the room is a bedroom, think about early light as well. A summer install means you live with bright early mornings straight away. There is a page on whether a bedroom skylight will wake you at dawn.
Timing questions people send us
A few practical points about booking and about the weather on the day.
Is it cheaper to install in winter?
Do not count on it. Prices follow the size, the glass and the roof, and the season is not a reliable factor. Our guide to what a quote should include shows what to compare instead.
Will a winter install leave my room cold?
Only for the hours the opening is being worked on. The old unit comes out and the new one goes in within the working day, and the room is covered at night. Clearing furniture from underneath makes it smoother.
Do I need scaffolding in any season?
That depends on the roof, not the month. Access for a roof window is often simpler than for a lantern. Whether you need scaffolding to replace a skylight is covered on its own page.
How far ahead should I ask?
As soon as you know the room. The survey comes first, and the quote and its written spec follow it. Ask early and you can pick your season. Start with a quote request, or look at the skylight and rooflight installation overview.