Job takeoff
Flat roof replacement (warm roof) takeoff
Strip an old flat roof and rebuild it warm: deck, insulation on top of it, the waterproofing you choose, upstands, flashings, gutter and the skip.
A takeoff is the trade word for the shopping list a job produces — every material, and how much of each, worked out by its own cited calculator.
- 7Measurements in
- 10Trades out
Choose the build-up
Each layer changes the materials below; the dimensions stay the same.
Calculators behind the other choices:
Compare one layer at these dimensions, with the rest of the build-up held as you have it:
Give the job once
Every figure on the right follows these, in the units you choose.
Been given a quote for this job?
Paste it into the flat roof replacement quote check: each line is read against these same calculators — what it leaves out, what it adds, and what to ask.
Check the quoteEvery trade, from those dimensions
then change a dimension, and each line shows what moved.
| Trade | Quantity | |
|---|---|---|
Dust sheets and tape in the room belowMasking and Protection Materials CalculatorDust sheets over the floor of the room under the roof, which is the plan area, and tape along its edges. Stripping an old deck drops dust and debris through the ceiling's gaps, and the sheets stay down until the new roof is watertight.
Why this quantity?
Resting on
Change any other figure on the Masking and Protection Materials Calculator | 3 items | |
Scaffold along the free edgesScaffold Face Area and Hire Quantity CalculatorFace area along every free edge at the height of the roof edge: the edge protection a flat roof is stripped behind, and the platform the waste and the rolls pass over. A roof reached from a tower with its own edge protection is listed as that item instead.
Why this quantity?
Resting on
Change any other figure on the Scaffold Face Area and Hire Quantity Calculator | 425 ft² of face | |
Insulation boards, flat, over a deck laid to fallsFoam Board Insulation CalculatorRigid insulation boards over the whole plan area, one layer, with the calculator's cutting allowance; a build in two layers with the joints staggered is this row twice. Under a tapered scheme the supplier cuts the falls into the boards from a drawing of the roof, and this count is the flat-board equivalent, for checking that the scheme covers the whole roof.
Why this quantity?
Resting on
The cutting waste: the calculator's working figure, a trade convention. Change any other figure on the Foam Board Insulation Calculator | 8 sheets (4x8 ft) | |
EPDM membraneEPDM Single-Ply Roofing Roll CalculatorThe plan area plus the upstands and the edge turn-downs, at the calculator's opening roll of 46.5 m² (500 sq ft). A small roof is covered from one sheet cut to size, so read the count as the area check and order the sheet by the roof's dimensions plus its upstands and turn-downs.
Why this quantity?
Resting on
Change any other figure on the EPDM Single-Ply Roofing Roll Calculator | 1 roll | |
Termination bar along the upstandsRoof Perimeter Termination Bar CalculatorBar along the top of every upstand against the house, with the calculator's allowance; the free edges are held by the edge trims instead.
Why this quantity?
Resting on
The waste allowance: the calculator's working figure, a trade convention. Change any other figure on the Roof Perimeter Termination Bar Calculator | 17.33 ft | |
Termination bar fixingsRoof Membrane Termination Bar Fastener CalculatorFixings for the bar the row above counts, at the calculator's opening spacing, as one continuous run; each separate length of bar takes one more.
Why this quantity?
Resting on
Change any other figure on the Roof Membrane Termination Bar Fastener Calculator | 19 fasteners | |
Cover flashing over the upstandsExterior Flashing Layout Trim Sheet CalculatorPieces of cover flashing along the length against the house, at the calculator's opening piece length of 3.05 m (10 ft), a US coil piece. Lead is cut shorter: the Lead Sheet Association keeps a Code 4 flashing to 1.5 m (5 ft) a piece, so set the piece length to what you buy and the count follows.
Why this quantity?
Resting on
Change any other figure on the Exterior Flashing Layout Trim Sheet Calculator | 2 sheets | |
Gutter along the low edgeGutter CalculatorGutter along the low edge, in 4 m (13 ft) lengths in metric and 10 ft sections in imperial; the row's working counts the downpipes (downspouts) the run needs.
Why this quantity?
Resting on
| 2 x 10 ft sections | |
Gutter brackets (hangers)Gutter Hanger Spacing CalculatorBrackets along the same run at the calculator's opening spacing of 24 in (610 mm), with one at each end; the gutter maker's own maximum spacing can be wider.
Why this quantity?
Resting on
Change any other figure on the Gutter Hanger Spacing Calculator | 10 hangers | |
Skip (dumpster) for the old roofSkip & Dumpster Size CalculatorThe loose volume of the old roof: the plan area times the loose depth you gave, as mixed construction waste. Order the skip (dumpster) at least this big, and larger where the deck comes off too.
Why this quantity?
Resting on
Change any other figure on the Skip & Dumpster Size Calculator | 1.32 yd³ | |
Dust sheets and tape in the room belowMasking and Protection Materials CalculatorDust sheets over the floor of the room under the roof, which is the plan area, and tape along its edges. Stripping an old deck drops dust and debris through the ceiling's gaps, and the sheets stay down until the new roof is watertight.
Why this quantity? | 4 items | |
Scaffold along the free edgesScaffold Face Area and Hire Quantity CalculatorFace area along every free edge at the height of the roof edge: the edge protection a flat roof is stripped behind, and the platform the waste and the rolls pass over. A roof reached from a tower with its own edge protection is listed as that item instead.
Why this quantity? | 39 m² of face | |
Insulation boards, flat, over a deck laid to fallsFoam Board Insulation CalculatorRigid insulation boards over the whole plan area, one layer, with the calculator's cutting allowance; a build in two layers with the joints staggered is this row twice. Under a tapered scheme the supplier cuts the falls into the boards from a drawing of the roof, and this count is the flat-board equivalent, for checking that the scheme covers the whole roof.
Why this quantity? | 8 sheets (2400x1200 mm) | |
EPDM membraneEPDM Single-Ply Roofing Roll CalculatorThe plan area plus the upstands and the edge turn-downs, at the calculator's opening roll of 46.5 m² (500 sq ft). A small roof is covered from one sheet cut to size, so read the count as the area check and order the sheet by the roof's dimensions plus its upstands and turn-downs.
Why this quantity? | 1 roll | |
Termination bar along the upstandsRoof Perimeter Termination Bar CalculatorBar along the top of every upstand against the house, with the calculator's allowance; the free edges are held by the edge trims instead.
Why this quantity? | 5.25 m | |
Termination bar fixingsRoof Membrane Termination Bar Fastener CalculatorFixings for the bar the row above counts, at the calculator's opening spacing, as one continuous run; each separate length of bar takes one more.
Why this quantity? | 19 fasteners | |
Cover flashing over the upstandsExterior Flashing Layout Trim Sheet CalculatorPieces of cover flashing along the length against the house, at the calculator's opening piece length of 3.05 m (10 ft), a US coil piece. Lead is cut shorter: the Lead Sheet Association keeps a Code 4 flashing to 1.5 m (5 ft) a piece, so set the piece length to what you buy and the count follows.
Why this quantity? | 2 sheets | |
Gutter along the low edgeGutter CalculatorGutter along the low edge, in 4 m (13 ft) lengths in metric and 10 ft sections in imperial; the row's working counts the downpipes (downspouts) the run needs.
Why this quantity? | 2 x 4 m sections | |
Gutter brackets (hangers)Gutter Hanger Spacing CalculatorBrackets along the same run at the calculator's opening spacing of 24 in (610 mm), with one at each end; the gutter maker's own maximum spacing can be wider.
Why this quantity? | 10 hangers | |
Skip (dumpster) for the old roofSkip & Dumpster Size CalculatorThe loose volume of the old roof: the plan area times the loose depth you gave, as mixed construction waste. Order the skip (dumpster) at least this big, and larger where the deck comes off too.
Why this quantity? | 1 m³ |
Estimates, not a quote. Each row gives its base, the allowance on top, the adjusted figure and what to order; change an allowance on the row, or open its reasoning to see every figure it rests on. A trade's own page carries what it does not cover — open the one you are about to order against.
Labour and programme
Person-hours for the rows going in, from trade rules of thumb: a range for each piece of work, never a price.
- Dust sheets and tape in the room below0.8 h (0.4–1.6)
- Insulation boards, flat, over a deck laid to falls3.6 h (2.0–10.0)
- EPDM membrane4.4 h (2.2–8.8)
- Termination bar along the upstands1.8 h (1.0–3.5)
- Cover flashing over the upstands4.5 h (1.5–9.1)
- Gutter along the low edge2.0 h (1.0–4.0)
- Skip (dumpster) for the old roof1.0 h (0.5–3.0)
About 18 person-hours in the rows that carry them, between 8.6 and 40.
Trade by trade
- Labourer1 labourerhalf a day
- Roofer2 roofers1 day
About 1½ days, one trade after another at eight hours a day. Left out: drying and curing, deliveries, inspections, trades overlapping.
3 rows carry no hours of their own
- Scaffold along the free edges: Scaffolding is not rated here: it is usually erected by a scaffolding firm and priced as hire, and where your own crew puts it up, the system and the height set the time.
- Termination bar fixings: counted with Termination bar along the upstands
- Gutter brackets (hangers): counted with Gutter along the low edge
Labour and programme
Person-hours for the rows going in, from trade rules of thumb: a range for each piece of work, never a price.
- Dust sheets and tape in the room below0.8 h (0.4–1.6)
- Insulation boards, flat, over a deck laid to falls3.6 h (2.0–10)
- EPDM membrane4.4 h (2.2–8.8)
- Termination bar along the upstands1.8 h (1.0–3.5)
- Cover flashing over the upstands4.5 h (1.5–9.0)
- Gutter along the low edge2.0 h (1.0–4.0)
- Skip (dumpster) for the old roof1.0 h (0.5–3.0)
About 18 person-hours in the rows that carry them, between 8.6 and 40.
Trade by trade
- Labourer1 labourerhalf a day
- Roofer2 roofers1 day
About 1½ days, one trade after another at eight hours a day. Left out: drying and curing, deliveries, inspections, trades overlapping.
3 rows carry no hours of their own
- Scaffold along the free edges: Scaffolding is not rated here: it is usually erected by a scaffolding firm and priced as hire, and where your own crew puts it up, the system and the height set the time.
- Termination bar fixings: counted with Termination bar along the upstands
- Gutter brackets (hangers): counted with Gutter along the low edge
Setups you have saved
The build-up, the dimensions and any allowance you changed — kept on this device, and reusable on any job. Your prices are not copied in: they stay in your price book, so a setup never holds a stale one.
How far does a budget go?
At your own prices, with this build-up unchanged.
About this job
Re-covering a flat roof means deciding where its insulation goes before a single roll is ordered. This page builds a warm roof: a vapour control layer laid on the deck, rigid insulation boards over that, and the waterproofing on top, so the joists and the ceiling void stay at room temperature and need no ventilation. The older way — insulation between the joists with a ventilated gap above it, the cold roof — keeps the deck cold, and a cold deck is where condensation collects. Warming the roof costs height: the finished surface rises by the insulation's thickness, so the upstands (base flashings, in US terms), the edge trims, the fascia and the threshold of any door onto the roof all move up with it.
The waterproofing is ordered for more than the roof. It runs up every wall the roof meets and turns down over every free edge, so the membrane rows here take the plan area plus a strip up each abutment at the upstand height you give and a strip along each free edge at the turn-down you give. The plan area alone buys the insulation, the dust sheets and a replacement deck. Where the roof butts against the house, the length against the wall also decides the cover flashing (counterflashing) and, on EPDM, the termination bar along the top of the upstand.
Two decisions change the item list most. The deck is kept by default, with its repair carried as a provisional item, because nobody can say how much of an old deck is rotten until the covering is off; choose to replace it and the boards become a row. And the falls: a flat roof built dead level holds ponds, so the fall comes either from timber firrings (tapered strips, called furring or sleepers in the US) under the deck or from tapered insulation boards cut to the falls — the second saves re-decking but makes the build-up deepest at the high end, where the upstands must clear it.
The membrane choice changes more than one line. EPDM (a synthetic rubber sheet) goes on cold as a single sheet cut to the roof, bonded down and held at the wall by a termination bar. Torch-on reinforced bitumen, the modern form of roofing felt, is two layers — an underlay and a mineral-surfaced cap sheet — melted on with a gas torch, which makes it hot work on a timber roof. GRP (glass-reinforced plastic, or fibreglass) is resin laid over glass mat on an overlay board with trims made for it. A liquid-applied membrane is brushed or rolled on cold over a primer, with a reinforcing mat bedded into it at every corner and upstand.
How each line reads
- Base
- What the calculator gives for these dimensions, before anything is added.
- Allowance
- Cutting waste, a lap or spare stock — named, with where it comes from, and changeable on the row.
- Adjusted
- The base with its allowance on top.
- Order
- What to buy: the adjusted figure in whole boards, bags, rolls or lengths.
The order this happens in
Quantities do not tell you the sequence, and on this job the sequence is where the money goes wrong.
- Before anything is ordered, open a corner: look at the deck, the joists and the wall plates, and whether the old layers are of an age that calls for an asbestos survey before they are disturbed.
- Put the edge protection up, sheet the room below, and have a temporary cover on site before the first strip — once the felt is off, the roof is a hole in the house.
- Strip in sections no bigger than can be made weathertight the same day, and bag the waste as it comes off rather than throwing it down.
- Replace rotten deck and fix the firrings, or check the existing falls, before anything covers them.
- Lay the vapour control layer over the whole deck, lapped and sealed and turned up at the edges, then the insulation boards tight and staggered, fixed through to the deck.
- Raise the edge timbers to the new height, fix the fascia, and set the drip trim along the gutter edge and the verge (rake) trims along the sides as the membrane system details them.
- Dress the membrane up the walls first where the system asks for it, then lay the field; on torch-on the underlay is completed before the cap sheet starts, with the laps of the two staggered.
- Finish the upstands under a cover flashing, hang the gutter to its fall, and run water across the roof to the outlet before the scaffold comes down.
What this takeoff does not cover
- The joists, the wall plates and whether they carry a warm roof's added weight. Any decay found is a provisional item here; how it is repaired, and whether the structure takes the new build-up, is for an engineer or the building control surveyor, and nothing on this page sizes a member.
- A cold roof, where the insulation stays between the joists under a ventilated void, and anything done inside the room: the ceiling, the vapour check in it and the lights in the void.
- Rooflights (skylights) and their kerbs, which are listed as work with no quantity row. On a warm roof the kerb stands on the insulation, and neither curb calculator on the site builds that detail.
- Quantities for the vapour control layer, the edge trims, the membrane adhesive and primers, and the insulation's fixings. The work is listed; no row measures it. The vapour control layer is roughly the plan area plus its upturn at the edges, and the trims are the free edges' length.
- Internal outlets, scuppers and any pipework inside the building. This page drains the roof to a gutter along its low edge; the gutter row's working counts the downpipes (downspouts), and the pipe is the drop to the ground times that count.
- Parapet walls round the roof and their copings. Where the roof is walled round, enter those walls as length against the house and the upstand rows run up them, but the coping, the damp course under it and any repair to the parapet itself are not measured.
- The insulation's thickness and the thermal performance it reaches, which are a design choice for the rules where you build; the board count is the same at any thickness, and a two-layer build is this row twice.
Quote check
Been given a quote for this job?
Paste it into the flat roof replacement quote check. Every line of it is read against these same calculators and your measurements. Quantities only, never prices.
What it leaves out
Every line this takeoff has that nothing on the quote reads as.
What it adds
Labour, removal, hire, fees — each named for what it is.
What to ask
One list of questions, ready to copy. Never a verdict.
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Frequently asked questions
- What does the flat roof replacement takeoff give for a typical job?
- Opened at Roof length, along the gutter 5 m · Roof width, the direction of fall 4 m · Length against walls of the house 5 m · Upstand height 0.15 m · Membrane turned over each free edge 0.1 m · Height of the roof edge above the ground 3 m · Loose depth of the old roof, stripped 0.05 m, it orders: Dust sheets and tape in the room below, 4 items; Scaffold along the free edges, 39 m² of face; Insulation boards, flat, over a deck laid to falls, 8 sheets (2400x1200 mm); EPDM membrane, 1 roll; Termination bar along the upstands, 5.25 m; Termination bar fixings, 19 fasteners; Cover flashing over the upstands, 2 sheets; Gutter along the low edge, 2 x 4 m sections; Gutter brackets (hangers), 10 hangers; Skip (dumpster) for the old roof, 1 m³. Opened at Roof length, along the gutter 16.5 ft · Roof width, the direction of fall 13 ft · Length against walls of the house 16.5 ft · Upstand height 6 in · Membrane turned over each free edge 4 in · Height of the roof edge above the ground 10 ft · Loose depth of the old roof, stripped 2 in: Dust sheets and tape in the room below, 3 items; Scaffold along the free edges, 425 ft² of face; Insulation boards, flat, over a deck laid to falls, 8 sheets (4x8 ft); EPDM membrane, 1 roll; Termination bar along the upstands, 17.3 ft; Termination bar fixings, 19 fasteners; Cover flashing over the upstands, 2 sheets; Gutter along the low edge, 2 x 10 ft sections; Gutter brackets (hangers), 10 hangers; Skip (dumpster) for the old roof, 1.32 yd³. Every figure follows the dimensions you give it.
- Which calculators does the flat roof replacement takeoff run?
- 10 calculators, one to a line: Masking and Protection Materials Calculator, Scaffold Face Area and Hire Quantity Calculator, Foam Board Insulation Calculator, EPDM Single-Ply Roofing Roll Calculator, Roof Perimeter Termination Bar Calculator, Roof Membrane Termination Bar Fastener Calculator, Exterior Flashing Layout Trim Sheet Calculator, Gutter Calculator, Gutter Hanger Spacing Calculator, Skip & Dumpster Size Calculator. Each has a page of its own with its formula and its sources; the takeoff runs them all on one set of dimensions.
- What does the flat roof replacement takeoff leave out?
- 7 things, each named on this page: The joists, the wall plates and whether they carry a warm roof's added weight; A cold roof, where the insulation stays between the joists under a ventilated void, and anything done inside the room; Rooflights (skylights) and their kerbs, which are listed as work with no quantity row; Quantities for the vapour control layer, the edge trims, the membrane adhesive and primers, and the insulation's fixings; Internal outlets, scuppers and any pipework inside the building; Parapet walls round the roof and their copings; The insulation's thickness and the thermal performance it reaches, which are a design choice for the rules where you build; the board count is the same at any thickness, and a two-layer build is this row twice.
- Can I check a quote for this job against the takeoff?
- Yes. The flat roof replacement quote check reads a quote's lines against these same calculators and your measurements, and reports what it leaves out, what it adds and what to ask. It reads quantities, never prices.