Can you replace a rooflight in winter?

Most of a rooflight swap happens in a short span. The old unit comes out, the new one goes in and is weathered, and from that point the opening is closed. If the work is planned so that the roof is sealed again the same day, the weather outside matters mainly for the hours in between.

That planning is simple but it matters. The new unit is on site and checked before the old one is touched. The flashing kit or the upstand materials are laid out. A temporary cover is ready for the case where the weather turns before the work is done. None of this is special to winter, but winter is when it counts most.

A few conditions make us move a date, and they are the same ones any roofer would name.

• Strong wind. Lifting a large pane or a roof lantern in a gale is unsafe, and a loose sheet or tile can become a hazard.
• Ice and frost on the roof. A frosted slate slope or a frozen flat roof is slippery, and the work waits until it has cleared.
• Heavy and persistent rain. A brief shower is manageable. A day of steady rain over an open frame is not, particularly on a large opening.
• Standing water on a flat roof. Roof coverings need a dry surface to be formed properly around a kerb.

When one of these is forecast, we agree a new day with you. A short delay is far better than a rushed job in bad conditions.

Some materials are sensitive to temperature, and winter planning allows for that. Sealants and adhesives have a working range, and a cold, damp surface can stop them bonding properly. Flat roof coverings that are bonded or welded need the right conditions to cure and seal. For these, the choice of product and the timing are adjusted to the day.

The glass is not a concern. A modern sealed unit is made to go through winter, and fitting it in cold weather does not affect its performance. What does matter is that the unit is handled with care, because cold glass is more brittle at its edges and a knock is less forgiving.

The other side of the job is the room. When the old unit is out, cold air comes in, and a heated bedroom or kitchen will feel it. We keep the time the opening is exposed short and protect the room beneath. Furniture is moved or covered, and the floor is sheeted so that falling debris or a spot of water does not mark it.

If you are replacing a misted or failed unit because the room has been cold or the glass has been clouding, the winter job gives you a quick change in comfort. There is more on why units fail in signs a rooflight needs replacing.

The finishing is more affected by winter than the roof work. Plaster dries slowly in a cold, damp house, and an unheated room can take noticeably longer to be ready for paint. A lime plaster in an old cottage is slower again, and in a cold snap it can be held up. Painting over plaster that has not dried leads to patchy colour, flaking and sometimes mould, so the schedule allows for dry time and does not rush to meet a date.

Heating the room, with a gentle and steady heat and some ventilation, helps. A dehumidifier is also useful. We will tell you what the room needs once the plaster is on. The finish schedule states whether the opening is left prepared for your own paint or already painted, so nobody is guessing what is finished on the day.

Short winter days shape the schedule more than the cold does. A job that would finish comfortably by late afternoon in June has less margin in December, because the roof must be closed and weathered before the light goes. So a winter day starts early with the roof work, and the finishing inside is left until the opening is sealed. We would rather split a large job across two days than leave an opening covered only by a temporary sheet overnight.

Daylight also helps the finish. A fresh plaster edge is judged by eye, and a low winter sun raking across the lining shows up every ripple. That is a good test of the work before we pack up.

We do not quote a general figure here, and it is not safe to assume a seasonal difference. Prices come from the survey and depend on the product, the size, the roof and the access. What winter does offer is a freer diary in some weeks, but the main reason to choose it is that the glass has failed and you do not want to live with it for another season.

The rules are the same in every month. A complete replacement, frame and glass, is notifiable building work that must meet Part L, and the Building Control notification is ours to deal with. A sealed glass unit alone, fitted to the existing frame, is not notifiable. Weather changes neither position.

1. Have the survey done early, so the unit is ordered and on site before the date.
2. Agree a second date in case the first is lost to the weather.
3. Decide how the inside will be finished, and allow dry time before decorating.
4. Clear the room, and keep it warm once the plaster is on.

For the order of work from the roof down, see how long it takes to replace a rooflight. When you are ready, ask for a quote and we will plan the job around your roof.