Commercial rooflight replacement is priced by the sheet, by the square metre of rooflight area and by the bay, not by a single domestic unit price, because the biggest cost drivers are access, phasing and profile availability rather than the sheet itself. A budget figure comes from applying a rate to your rooflight area and adjusting for how the work has to be done. A firm figure comes from a survey that takes the profile, measures the spans, agrees the phasing and turns the whole roof into a scope priced by bay, which is then fixed against that scope.
This page sets out how commercial rooflight replacement is costed. It sits under our commercial skylight installation service, and it is for facilities managers and building owners who need a defensible number for a capital plan before, and after, a survey. The rates here are for budgeting. Once we have surveyed your roof, you get one fixed figure.
Why it does not price like a domestic unit
A domestic rooflight has a unit price because it is one opening in one roof with a known access. A commercial roof has none of that certainty. The same sheet costs very different amounts to install depending on how high the roof is, how it is reached, whether the building is working below, whether the profile is still made, and whether the work runs by day or by night. Publishing a price per rooflight would be misleading, because the sheet is often the smallest part of the number.
The three ways it is budgeted
- Per square metre of rooflight area. The headline budgeting rate. Multiply the rooflight area by a rate for the build-up and material, and you have a first-pass figure. Best for estimating a whole roof or a large phase.
- Per sheet. Useful where the work is a defined number of in-plane sheets. The rate per sheet falls sharply with volume, because access is shared. An isolated single sheet prices at the top of the range.
- Per bay. How the firm scope is usually structured, because a bay is the unit that gets opened, worked and closed. Bay pricing captures the access and the sheets together, and it lets a phase sit inside a specific year’s budget.
Budget rates for the region
The ranges below are supply-and-fit budget figures for Ipswich, Suffolk and north Essex, on buildings with reasonable roof access, working normal hours, with netting included and material in standard production. They are for getting a number into a capital plan before a survey.
| Scope | Budget rate | Basis | What sets it |
|---|---|---|---|
| In-plane GRP replacement, single skin | £110 to £190 per m² | Per m² of rooflight | Standard profile, polyester film, normal hours |
| In-plane GRP replacement, twin skin with liner | £165 to £270 per m² | Per m² of rooflight | Includes liner rooflight and cavity detailing |
| Typical single in-plane sheet, 3.0m x 1.0m | £380 to £780 per sheet | Per sheet | Rate falls with volume, isolated sheets top the range |
| Moulded-to-match, discontinued profile | Add 25 to 60% | Per sheet | Tooling and minimum order quantity |
| High performance surface film upgrade | Add 12 to 25% | Per m² | Usually the best-value decision in the spec |
| Barrel vault on new kerb | £520 to £950 per m² | Per m² | Includes kerb formation and weathering |
| Continuous rooflight run | £4,500 to £11,000 per bay | Per bay | Bay width, run length and build-up |
| Safety netting | £9 to £18 per m² | Per m² netted | Included in phase pricing, not added later |
| Coastal and port-side upgrade | Add 8 to 15% | Per phase | 316L stainless throughout, marine coatings, cut-edge treatment |
| Out-of-hours or night working | Add 30 to 55% | Per phase | Labour premium and task lighting, priced openly |
| Mobile platform or crane access | Quoted separately | Per phase | Site dependent, often the largest single variable |
What drives the number up or down
Access equipment
How the roof is reached is frequently the largest single line, and it is the one that varies most between buildings. A low single-storey shed with a safe internal route is cheap to access. A high roof, a roof over live plant, or one that needs a mobile elevating work platform or a crane to reach, carries an access cost that can rival the rooflight cost itself. This is why two roofs with identical rooflight areas can price very differently, and why access is quoted against the actual site rather than assumed.
Phasing
Spreading the work across phases and financial years spreads the cost, but each mobilisation carries its own access and set-up cost. There is a trade-off: more phases mean smaller annual bills and more total mobilisations, fewer phases mean larger bills and better unit rates. The sensible phasing balances your budget against the mobilisation cost, and it is set at survey. Our phased rooflight replacement programme answer covers how phases are structured.
Out-of-hours working
Night and shutdown working adds a labour premium and the cost of task lighting, and it is priced openly rather than absorbed. Where a building can only be worked out of hours, this is a real cost, not an optional extra, and it belongs in the budget from the start.
Profile availability
A standard, still-made profile is a straightforward order. A discontinued profile needs a sheet moulded to match, which carries tooling and minimum-order costs. On older Ipswich stock this is common, and it is established at survey when the profile is taken physically off the roof.
What a per-square-metre rate does and does not include. The rates above cover supply and fit of the rooflight and its laps, fixings and, where twin skin, the liner, with netting, working in normal hours, on a roof with reasonable access. They do not include specialist access equipment, out-of-hours premiums, discontinued-profile tooling, coastal upgrade packages, structural work to purlins, or AOV smoke ventilation units. A rate quoted without saying what it excludes is a rate that will grow. Ours name the exclusions.
A worked budget example
Take a distribution unit with a 3,000 square metre roof carrying in-plane GRP rooflighting at 12 per cent, so around 360 square metres of rooflight, twin skin, standard profile, accessible roof, working normal hours.
- 360 m² of twin-skin rooflight at, say, £215 per m² gives a budget of roughly £77,000 for the rooflights themselves, netting included.
- A high performance surface film upgrade at 15 per cent adds around £11,500 and lengthens the interval before the next replacement.
- If the roof needs a mobile platform to reach, that is quoted separately and could add a five-figure sum depending on height and the number of set-ups.
- If the site can only be worked at night, the out-of-hours premium at 40 per cent applies to the labour element.
- If the profile turns out to be discontinued, moulded-to-match sheets add 25 to 60 per cent on the sheet cost.
The point of the example is that the rooflight figure is the stable, predictable part, and the variables sitting on top of it, access, hours and profile, are what make two similar roofs price differently. This is why a budget built from the per-square-metre rate alone, without an allowance for those variables, tends to come in low. A sensible budget takes the rate and adds a realistic allowance for the access and working pattern you already know your building needs.
Disposal and what the survey finds
Two cost elements are easy to overlook. Disposal of the old GRP is construction waste that has to be taken off site and disposed of properly, and it is in our rates rather than added later. And a roof, once opened, sometimes reveals corroded purlins or fixing points that need attention before the new rooflight goes on. We flag the risk of this at survey where the age and exposure suggest it, so it is a considered allowance rather than a surprise variation. On coastal and older stock it is worth budgeting a contingency for it. Our coastal industrial roof corrosion answer covers where that risk is highest.
How the survey turns a roof into a fixed figure
The budget rates get you a planning number. The survey gets you a figure you can hold. We arrange access with your team, take the profile physically off the sheeting, measure the purlin spans, confirm the build-up, assess the existing fixings and cut edges, identify any AOV positions and fire strategy, and record every rooflight position on a plan. From that we build a scope priced by bay, with the material, the film grade, the liner treatment, the lap details, the fixing grade, the access method and the phasing all specified. That figure is then fixed against that scope, and it does not move unless the scope does.
Why can you not just give a price per rooflight?
Because the sheet is often the smallest part of the cost. The same rooflight costs very different amounts to install depending on the roof height and access, whether the building is working below, whether the profile is still made, and whether the work runs by day or night. A price per rooflight would ignore all of that. Commercial rooflight work is budgeted per square metre, per sheet and per bay, and priced firmly from a survey.
What is usually the biggest cost on the job?
Frequently access rather than the rooflights. A high roof, a roof over live plant, or one needing a mobile platform or crane carries an access cost that can rival the cost of the sheets. This is why two roofs with the same rooflight area can price very differently, and why access is always quoted against the actual site.
Is the surface film upgrade worth the extra?
Usually yes. Upgrading to a high performance surface film adds roughly 12 to 25 per cent per square metre and extends the service life of the sheet considerably, so it lengthens the interval before the next replacement and the next round of access cost. On a roof that is hard to access, or a phased programme you would rather not repeat, it is often the best-value decision in the whole specification.
Get a fixed figure for your roof
Use the rates above to build a budget, then let a survey turn it into a number you can commit to. We survey the whole roof, take the profile, agree the phasing, and come back with a scope priced by bay and one fixed figure against it.
Request a survey. Read across to warehouse rooflight replacement cost and cost per square metre, and see all published rates on the costs page.
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.