What Does It Cost to Replace Several Rooflights at Once?
Replacing several rooflights at once is cheaper per unit than doing them one at a time, because the fixed costs of a job, access, setup, disposal and a single visit, are spread across all the units instead of being paid on each. The unit cost and the kerb work do not fall much, because each rooflight still needs its own glass and its own kerb, but the shared overheads can be a meaningful part of a small job, so combining them takes real money off the total. As a rough guide, doing two units together rather than separately saves the cost of one extra mobilisation, and the saving per unit grows as the number rises.
This page explains where the savings are real and where they are not, so you can judge a multi-unit quote honestly. The full cost structure is on flat roof rooflight installation cost, a single unit is worked on how much a 1m rooflight costs fitted, and the wider job is on flat roof skylight installation.
Where the savings are real
The economies come from the parts of a job you pay for once regardless of how many rooflights are involved.
- Access and setup. A tower and edge protection, or scaffold on a two-storey job, is set up once and serves every unit on that roof. On a single small rooflight, access can be a noticeable slice of the price. Spread across three units it is a third each.
- Mobilisation. Getting the team, tools and materials to site is a fixed cost per visit. One visit for three units beats three visits for one.
- Disposal. Stripping out old domes and offcuts is one skip or one load, not several.
- Survey and admin. One survey, one quote, one Building Control application where the units are all on the same roof and job.
- Delivery. Units delivered together in one consignment rather than separately.
Where the savings are not
It is worth being honest about the parts that do not scale, because a multi-unit quote is not simply the single price multiplied down.
- The units themselves. Each rooflight is its own piece of glass at its own price. Three units cost roughly three units, with only a modest supply saving on a larger order.
- The kerbs. Every unit needs its own kerb built or rebuilt. On replacements, each kerb is its own unknown until its old unit is off, so each carries its own provisional rebuild allowance.
- The weathering. Each unit is dressed into the covering individually. There is no shortcut across separate openings.
- Internal finishing. Each opening has its own reveals to form and finish.
| Cost | Shared across units? |
|---|---|
| Access and setup | Yes, paid once |
| Mobilisation and visits | Yes, one visit |
| Disposal | Yes, one load |
| Survey and application | Yes, one of each |
| The units | No, one each |
| Kerb works | No, one each |
| Weathering | No, one each |
| Internal finishing | No, one each |
A rough picture
To put numbers on it, two 1.2 by 1.2m units on one roof run £4,300 to £5,700 together. Priced as two entirely separate visits they would come to more, because you would pay access, mobilisation and disposal twice. The saving is the value of one avoided mobilisation, spread across the job. On three or four units the shared costs are divided further, so the per-unit figure keeps dropping, though never below the cost of the glass, the kerb and the weathering that each unit needs on its own.
Combine what is genuinely due, not what is not. If several rooflights on your roof are the same age and failing together, doing them in one job is a real saving. If only one has failed and the others have years left, replacing all of them to save on access rarely pays. We will tell you honestly which of yours are due, rather than selling you a full set.
Doing them together on site
On a multi-unit job the openings are worked one at a time, so the roof is never widely open at once, which is why the total runs to two or three days rather than one. Each unit is stripped, its kerb inspected and rebuilt if needed, weathered in and set, before the next is opened. The roof is watertight at the end of each day. The shared access and one team moving between openings is exactly where the efficiency comes from.
Suffolk and north Essex specifics
Multi-unit replacements come up often locally, because the flat-roofed extensions and garages built in one era failed in the same era. A property at Kesgrave or Rushmere with a run of 1980s domes across a garage and utility roof is a natural multi-unit job, and doing them together is the sensible way to spend the money. On a larger side-return kitchen, two units often light the room better than one anyway, so a two-unit job is as much about daylight as economy. On the coast at Felixstowe the shared marine-spec order across several units also saves a little on supply.
Common questions
Is it cheaper to replace several rooflights at once?
Yes, per unit, because access, setup, disposal, survey and mobilisation are paid once and shared across all the units rather than repeated on each. The glass, the kerb and the weathering do not scale, since each unit needs its own, but the shared overheads are a real saving, roughly the value of the extra visits you avoid.
Should I replace all my rooflights if only one has failed?
Only if the others are also near end of life. If several are the same age and failing together, doing them in one job saves on the shared costs. If one has failed and the rest have years left, replacing all of them to save on access rarely pays. We tell you honestly which are due rather than selling a full set.
How long does a multi-unit job take?
Two to three days for two units, more for more, because the openings are worked one at a time so the roof is never widely open. Each unit is stripped, its kerb checked, weathered in and set before the next is opened, and the roof is watertight at the end of each day. The shared access is what makes it efficient.
Get a multi-unit price
Tell us how many rooflights, their rough sizes, whether they are replacements or new openings, and where the property sits. We will survey them, tell you honestly which are genuinely due, and give you one written fixed price that shares the access and setup properly across the job. Every installation carries a 10-year workmanship guarantee.
Request a fixed quote in Ipswich, Suffolk or north Essex.
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.