THE ESTIMATING ANSWER
For one existing roof opening, start with a defined scope and measurement basis. Measure the structural opening, roof covering type, pitch and interior reveal. Keep unit, manufacturer-matched flashing and interior finish allowance separate. Price the listed tasks separately and state the condition that would require a revision: Rotten curb or incompatible opening changes framing and waterproofing scope.
This guide follows one existing roof opening in Melbourne, Victoria. The matching itemised estimate and PDF show how the job brief becomes measured quantities and separate AUD amounts. The responsible role in this scenario is roofing contractor. Check the actual site, selected products, supplier figures and labour plan before issuing a client quote.
Skylight replacement: separate the roof opening from the glazing allowance
A skylight replacement quote should confirm whether the existing opening can remain and identify the exact replacement unit. Record the visible dimensions, roof covering, interior shaft finish and any signs of leakage for the roofer's review. A like-for-like replacement and an enlarged opening are different jobs even when the glazing area looks similar in a product catalogue or a photograph.
Keep the selected skylight, compatible flashing, removal, roof access, fitting and internal making good as separate allowances. Ask who checks the existing surrounding material and how discovered damage will be priced. Interior edge repair, complete shaft redecoration and structural alteration should each be described explicitly; they should not be inferred from the phrase replace one skylight on a quotation.
When asking about replacing an old skylight in Melbourne, share the same roof photographs and opening information with each supplier. Confirm whether product measurement, temporary weather protection and waste removal are included. Compare the full installation scope before comparing the product allowance, and keep any concealed roof damage as a documented change trigger.
A separate worked planning example
Illustrative comparison: one existing opening, one selected replacement skylight and one matching flashing set. Count interior repair as its own measured or fixed allowance. This example does not set an opening size or establish that an old and new product are interchangeable.
Cost and scope questions
Can I quote a replacement using the visible glass size?
Use that measurement only as preliminary information. The installer must confirm the product dimensions, opening and flashing arrangement before selection or fabrication.
Does a skylight replacement include repainting the whole ceiling?
Only when named in the scope. A local interior edge-repair allowance is different from repainting the shaft or the whole room.
1. Define the measured job
Replace one roof window or skylight in the existing suitable opening, with matching flashing kit and interior edge repair. Measure the structural opening, roof covering type, pitch and interior reveal. Record the measurements and existing condition in the estimate before turning quantities into line items. The scope should make clear why this is a separate project from a broader renovation or maintenance quote.
Measure for this job: Measure the structural opening, roof covering type, pitch and interior reveal. Put that measured basis beside the relevant PDF lines so area, fitted length and product purchase quantities stay distinct.
2. Build a product and labour schedule
Keep unit, manufacturer-matched flashing and interior finish allowance separate. This example has 7 distinct lines, including opening and access survey, temporary roof protection, old skylight removal. Use actual supplier prices and labour inputs for a customer job; the displayed amounts are fictional document inputs.
Choose before pricing: Keep unit, manufacturer-matched flashing and interior finish allowance separate. The fixture separates opening and access survey, temporary roof protection and old skylight removal rather than hiding all work in one figure.
3. Sequence the work and handoffs
Confirm product and safe roof access before removing the old unit. Show which task depends on access, a selected product or another trade. If that dependency is still open, label the price preliminary and identify the information needed before a firm quote.
Plan the handoffs: Confirm product and safe roof access before removing the old unit. Note which stage needs access, a selected product or another trade before the next stage can be priced confidently.
4. Set a change boundary
Rotten curb or incompatible opening changes framing and waterproofing scope. The example excludes new roof opening, ceiling renovation or concealed structural repair. Record the discovery, agree the revised work and update the estimate before adding it to the job.
Change trigger: Rotten curb or incompatible opening changes framing and waterproofing scope. Record the revised task and quantity before it changes the amount your client sees.
Review the Australian job
Check access, substrate, drainage and product delivery at the property. Record weather and site conditions that affect the work, and confirm any design or approval requirements for the real scope.
Count the actual products, site visits and specialist tasks separately. This fixture is a document example, not a substitute for inspecting the building. The amounts are fictional AUD inputs, not current prices for Melbourne, Victoria or another location.
Worked project calculation
The paired PDF has 7 cost lines. For example, Old skylight removal is 1 each × A$398.75 = A$398.75; Skylight unit allowance is 1 each × A$1,443.75 = A$1,443.75. Each amount comes from the stated quantity and unit rate, so you can trace the arithmetic back to the job scope.
| Work item | Quantity | Unit rate | Amount |
|---|---|---|---|
| Opening and access survey | 1 job | A$343.75 | A$343.75 |
| Temporary roof protection | 1 job | A$316.25 | A$316.25 |
| Old skylight removal | 1 each | A$398.75 | A$398.75 |
| Skylight unit allowance | 1 each | A$1,443.75 | A$1,443.75 |
| Flashing kit allowance | 1 set | A$371.25 | A$371.25 |
| Installation and weathering | 1 each | A$852.50 | A$852.50 |
| Interior trim and cleanup | 1 job | A$426.25 | A$426.25 |
| Illustrative total | A$4,152.50 | ||
Adding every exact-cent line gives A$4,152.50. The PDF uses a 0% tax input only to make its fictional arithmetic visible. Confirm the GST treatment that applies to the actual job and set your own markup before sharing a client quote. A fictional rate is a document input, not a market quote or a recommended selling price.
Scope and pricing boundaries
Replace one roof window or skylight in the existing suitable opening, with matching flashing kit and interior edge repair.
Outside this example: No new roof opening, ceiling renovation or concealed structural repair.
Separate product allowances, supply, installation, disposal and any specialist work where the actual project needs them. If access or a hidden condition changes, document the affected scope and agree a revised price instead of silently extending the base amount.
Before you send the estimate
- Measure the structural opening, roof covering type, pitch and interior reveal.
- Keep unit, manufacturer-matched flashing and interior finish allowance separate.
- Confirm product and safe roof access before removing the old unit.
- Rotten curb or incompatible opening changes framing and waterproofing scope.
Check business and client details, address, dates, scope, units, line amounts and PDF notes. The skylight replacement PDF example shows how this fictional project is presented. Its short PDF note is not a substitute for the detailed exclusions above.
Questions about this estimate
Which quantity controls this skylight replacement estimate?
Measure the structural opening, roof covering type, pitch and interior reveal.
When should this skylight replacement quote be revised?
Rotten curb or incompatible opening changes framing and waterproofing scope. No new roof opening, ceiling renovation or concealed structural repair.
TURN THE SCOPE INTO AN ITEMISED PDF
Make your own skylight replacement estimate.
Describe the actual job in Estimates on iPhone or Android or use AI assistance to start a draft. Check every measurement, quantity, rate, allowance, client detail and note before exporting your PDF. Some app features may require an in-app purchase.
