A like-for-like flat rooflight replacement into a sound kerb is a one-day job, and the roof is never left open overnight. A new opening with structural trimming runs to one or two days on site. Several units on one roof take two to three days. Beyond that, the things that push a job longer are a rotten kerb that needs rebuilding, falls that need correcting, structural work needing an engineer, and difficult access. Plaster drying is separate and sits on your programme, not ours.
Those are the site durations. They do not include the lead time before work starts, which is two to four weeks while a made-to-measure unit is built, longer for marine coatings, oversized glass, walk-on units or electric openers. Nothing starts on site until the unit is physically in stock, because we do not open a roof waiting on a delivery.
By job type
| Job | Days on site | Roof open |
|---|---|---|
| Dome or unit swap into a sound kerb | 1 | Hours, weathered in the same afternoon |
| Replacement where the kerb needs rebuilding | 1 to 2 | First day, closed each night |
| New opening, standard trimming | 1 to 2 | Most of the first day |
| Two or more units on one roof | 2 to 3 | Managed one opening at a time |
| Electric opening unit | 2 | First day, plus wiring and commissioning |
| Walk-on unit to engineer’s design | 3 to 4 | Structural work extends it |
The one-day replacement
On a straight swap into a kerb that turns out sound, the sequence is quick. The old unit comes off in the morning, the kerb is inspected, the covering is dressed in, and the new unit is set and watertight the same afternoon. This is the most common flat rooflight job we do, particularly the 1980s and 1990s dome replacements across Kesgrave, Rushmere and Chantry, and on a good kerb it genuinely is a day.
The new opening
A new opening adds the structural work. The covering comes back, the deck is marked out, trimmers go in and are fixed, props go under where the span needs them, and only then is the deck cut. The upstand is built, the falls checked, the covering dressed over the head, and the unit set. On a straightforward domestic opening up to about 1.2m that is one long day or spills into a second. The roof is open for most of the first day and closed watertight before we leave.
What pushes a job past two days
- A rotten kerb. On a replacement, if the timber is gone the kerb is rebuilt insulated, which adds most of a day. This is the most common reason a one-day job becomes two, and it cannot be known until the old unit is off. The detail is on leaks at the rooflight kerb.
- Correcting the falls. If the roof ponds, re-firring or laying tapered insulation around the opening adds time. Why it matters is on why flat rooflights pond water.
- Structural work. An opening over about 1.5m, or into an unknown or historic structure, needs an engineer’s design first, and the trimming or steel it specifies takes longer to install.
- Several units. Two or more openings are worked one at a time so the roof is never widely open, which spreads the job across two or three days. The economics of that are on the cost of replacing several rooflights.
- Access. Single-storey work uses a tower set up the day before. Two-storey or restricted access needs full scaffold, which adds set-up time.
- Weather. We do not press on and hope in bad weather. If finishing is impossible we sheet and secure properly and return, which can add a day.
The roof is watertight at the end of day one, every time. Whatever the total duration, we work to make the roof weathertight before we leave on the first day, with or without the glass on it. We never leave a flat roof open overnight.
Suffolk and north Essex specifics
Two local factors touch timing. Coastal work at Felixstowe and Harwich takes the full marine specification, and while the fitting is not much slower, the lead time on marine-coated units is longer, so plan further ahead there. And the age of the stock matters: the older flat-roofed rear additions behind central Ipswich terraces, and the 1970s and 1980s estate garages, are the jobs most likely to turn up a rotten kerb once opened, so a one-day estimate on those carries the honest caveat that it may become two. We flag that at survey rather than after the unit is off. Estuarine areas such as Woodbridge fit on standard timings with upgraded fixings.
Lead time, before any of this
The days on site are only part of the calendar. A flush glass unit is made to your surveyed size, so there is a lead time of two to four weeks for standard sizes and finishes before the fitting days begin, and longer for marine coatings, oversized single panes, walk-on glass or electric openers. We book the fitting for when the unit is in, not before, so the roof is only ever opened once everything needed to close it is on hand.
Common questions
Will my roof be left open overnight?
No. We work to make the roof watertight before we leave on the first day, with or without the glass on it. On a replacement it is weathered in within hours. On a new opening the roof is closed watertight at the end of the first day. If weather makes finishing impossible we sheet and secure properly and return.
How long from ordering to fitting?
Two to four weeks for a standard flush glass unit made to your surveyed size, longer for marine coatings, oversized glass, walk-on units or electric openers. The fitting days are booked for when the unit is physically in stock. We do not open a roof waiting on a delivery.
Does plaster drying add to the time?
The fitting and weathering are done in the site days above. Where internal finishing is in scope, the plaster and skim on the reveals then need normal drying time before painting, which sits on your programme rather than ours. The rooflight is watertight and finished structurally well before the plaster is dry.
Get a fixed price and a date
Send us the roof size, whether it is a new opening or a replacement, the covering if you know it, and where the property sits. We will survey it, give you one written fixed price and an honest duration, and flag any risk of a kerb rebuild before the job rather than after. Every installation carries a 10-year workmanship guarantee.
Request a fixed quote for a flat rooflight in Ipswich, Suffolk or north Essex. The wider job is on flat roof skylight installation.
Thinking about this job? We survey across Ipswich, Suffolk and north Essex and give you a fixed price before any work starts, with a 10-year workmanship guarantee.