Job takeoff
Loft conversion with a dormer takeoff
Turn a loft into a room under a rear box dormer: the dormer's deck, warm-roof insulation and waterproofing, the cheeks' membrane and flashings, the knee wall and partitions, insulation, boards and finishes, and an optional shower room, with the floor, the steels, the dormer's frame and the stair listed and never sized.
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.
- 17Measurements in
- 3231Trades out
Choose the build-up
Each layer changes the materials below; the dimensions stay the same.
Calculators behind the other choices:
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 loft conversion 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 in the rooms belowMasking and Protection Materials CalculatorSheets over the bedrooms and landing under the loft, taken as the new floor's area, and tape round their edges: laying joists and opening the roof drops dust through every gap in the ceiling below.
Why this quantity?
Resting on
Change any other figure on the Masking and Protection Materials Calculator | 5 items | |
Scaffold across the backScaffold Face Area and Hire Quantity CalculatorThe back elevation's width at the height of the eaves plus the room height, up to where the dormer's roof is laid; a cover over the opened slope is listed with it.
Why this quantity?
Resting on
Change any other figure on the Scaffold Face Area and Hire Quantity Calculator | 477.75 ft² of face | |
Deck on the dormer's roofPlywood and OSB Sheet Calculator (Subfloor, Wall and Roof)Full 2440 × 1220 mm (4 × 8 ft) sheets over the dormer's plan, with the calculator's cutting allowance; the firrings under them, where the fall is formed in timber, are listed.
Why this quantity?
Resting on
The waste factor: the calculator's working figure, a trade convention. Change any other figure on the Plywood and OSB Sheet Calculator (Subfloor, Wall and Roof) | 6 sheets (4x8 ft) | |
Warm-roof boards on the dormerFoam Board Insulation CalculatorRigid boards over the dormer's deck on the vapour control layer, one layer at the calculator's opening sheet and allowance; the thickness is the energy calculation's, and a second layer is this row again.
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 | 6 sheets (4x8 ft) | |
EPDM on the dormerEPDM Single-Ply Roofing Roll CalculatorThe dormer's plan area at the calculator's opening roll, a figure to check the sheet against: the dormer is covered from one sheet cut to its width and depth plus the strip turned up under the main roof's tiles at the back and down over the trims at the front and sides.
Why this quantity?
Resting on
Change any other figure on the EPDM Single-Ply Roofing Roll Calculator | 1 roll | |
Termination bar at the back upstandRoof Perimeter Termination Bar CalculatorBar along the back of the dormer's roof, where the membrane turns up under the main roof's underlay and tiles, with the calculator's allowance; the front and the sides are held by edge trims.
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 length.
Why this quantity?
Resting on
Change any other figure on the Roof Membrane Termination Bar Fastener Calculator | 19 fasteners | |
Fascia along the dormer's frontFascia Board CalculatorFascia across the dormer's face in stock lengths with the calculator's allowance, raised to clear the warm roof's build-up; the edge trims over it are listed.
Why this quantity?
Resting on
The cut and scarf allowance: the calculator's working figure, a trade convention. | 2 x 12 ft boards | |
Breathable membrane on the cheeksRoofing Underlayment CalculatorMembrane over both cheeks behind the tile-hanging, with the calculator's lap allowance, in its 1,000 sq ft (about 93 m²) synthetic rolls; a British breathable membrane comes in smaller rolls, bought by the lapped area in the working. The strip where the main roof's underlay is cut back round the dormer is made good from the same roll.
Why this quantity?
Resting on
The overlap allowance: the calculator's working figure, a trade convention. Change any other figure on the Roofing Underlayment Calculator | 1 roll | |
Flashing down both cheeksExterior Flashing Layout Trim Sheet CalculatorFlashing where each cheek meets the main roof, the dormer's depth lengthened by the slope factor, both sides, in pieces at the calculator's opening length, a US coil piece. Lead is cut shorter, often with a soaker under every tile course, so set the piece to what you buy.
Why this quantity?
Resting on
Change any other figure on the Exterior Flashing Layout Trim Sheet Calculator | 3 sheets | |
The dormer's own gutterGutter CalculatorGutter across the dormer's face, in stock sections; the working counts the downpipes (downspouts). A dormer draining onto the main roof below takes a short pipe to the lower gutter instead.
Why this quantity?
Resting on
| 2 x 10 ft sections | |
Flashing tape round the dormer windowsWindow Opening Flashing Membrane CalculatorSelf-adhered tape round each window in the timber face, sill, jambs and head, with the calculator's run-past and allowances; the windows are items.
Why this quantity?
Resting on
The waste allowance: the calculator's working figure, a trade convention. Change any other figure on the Window Opening Flashing Membrane Calculator | 48.4 ft | |
Studs for the knee wall and the partitionsFraming Stud CalculatorStuds at the calculator's opening centres along the knee wall, the loft's length, and the new partitions, with a king and a jack stud each side of every door. Head and sole plates, about twice the length in timber, are not in the count.
Why this quantity?
Resting on
| 39 studs | |
Boards between and under the sloped raftersFoam Board Insulation CalculatorRigid boards over the sloped ceiling above the knee wall, the area on the slope, at the calculator's opening sheet and allowance, whether they are cut between the rafters or fixed under them; a layer of each is this row twice.
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 | 4 sheets (4x8 ft) | |
Batts in the knee wall, cheeks and faceMineral Wool Insulation Batt CalculatorBatts between the studs of the knee wall, the two cheeks and the dormer's face less its windows, at the calculator's opening pack and allowance.
Why this quantity?
Resting on
The waste allowance: the calculator's working figure, a trade convention. Change any other figure on the Mineral Wool Insulation Batt Calculator | 6 packages | |
Sound insulation between the floor joistsMineral Wool Insulation Batt CalculatorBatts laid between the new joists over the whole floor before it is decked, for the sound separation a new floor over bedrooms needs.
Why this quantity?
Resting on
The waste allowance: the calculator's working figure, a trade convention. Change any other figure on the Mineral Wool Insulation Batt Calculator | 8 packages | |
Insulation over the flat ceiling beyond the dormerMineral Wool Insulation Batt CalculatorBatts or quilt over the part of the flat ceiling the dormer's warm roof is not above: the strip under the cold void at the ridge, and any strip beside a dormer narrower than the loft, taken as the flat ceiling less the dormer's plan. The thickness is the energy calculation's; a second, cross-laid layer is this row again.
Why this quantity?
Resting on
The waste allowance: the calculator's working figure, a trade convention. Change any other figure on the Mineral Wool Insulation Batt Calculator | 3 packages | |
Plasterboard (drywall) on the ceiling and slopeCeiling Plasterboard (Gypsum Board) Sheet CalculatorBoard over the flat ceiling and the sloped strip, at the calculator's opening sheet and allowance.
Why this quantity?
Resting on
The waste allowance: the calculator's working figure, a trade convention. Change any other figure on the Ceiling Plasterboard (Gypsum Board) Sheet Calculator | 13 sheets | |
Plasterboard (drywall) on the wallsCeiling Plasterboard (Gypsum Board) Sheet CalculatorBoard over the knee wall, the face less its windows and the two end walls, the end walls less the triangle under the slope at each, at the same sheet and allowance. The end walls are taken at the room height right back to the face, so the inside of each cheek is already in them and is not boarded twice. An end wall plastered straight onto the masonry is the same area in plaster.
Why this quantity?
Resting on
The waste allowance: the calculator's working figure, a trade convention. Change any other figure on the Ceiling Plasterboard (Gypsum Board) Sheet Calculator | 15 sheets | |
Board on both faces of the partitionsMulti-Layer Fire-Rated (Type X) Gypsum Sheet CalculatorOne layer each side of the new partitions, the length by the room height, at the calculator's opening sheet, with nothing added for cutting. Where the partitions enclose the escape, the board and the layers are the ones the fire resistance asks for.
Why this quantity?
Resting on
Change any other figure on the Multi-Layer Fire-Rated (Type X) Gypsum Sheet Calculator | 10 sheets | |
Joint compound for taping and filling every boardDrywall Joint Compound CalculatorCompound for taping and filling the ceiling, the slope, the walls and both faces of the partitions, with the calculator's pan and sanding allowance: whole boxes with imperial showing, the weight of ready-mixed compound with metric.
Why this quantity?
Resting on
The pan and sanding loss: the calculator's working figure, a trade convention. Change any other figure on the Drywall Joint Compound Calculator | 3 x 4.5 gal boxes | |
Paper joint tape over every boardDrywall Joint Tape CalculatorPaper tape for the joints between boards at the calculator's rate for its opening 8 ft (2.4 m) boards, and for the internal angles, each once: where the knee wall meets the slope and the slope meets the flat ceiling, the ceiling's edge along the face and along both end walls, up the slope included, the four corners floor to ceiling, and the ceiling's edge along both faces of the partitions. The corners where a partition meets a wall are not counted, and the window reveals take bead, which this row does not count.
Why this quantity?
Resting on
The waste allowance: the calculator's working figure, a trade convention. Change any other figure on the Drywall Joint Tape Calculator | 629.42 ft | |
Tanking in the shower roomCold-Applied Liquid Waterproofing Membrane Volume CalculatorLiquid membrane over the shower room's floor and its walls to the tiled height, at the calculator's opening film and solids; a tanking kit states its own coats and coverage, so set both from its data sheet. The tape at every corner and the collars round the pipes come in the kit.
Why this quantity?
Resting on
Change any other figure on the Cold-Applied Liquid Waterproofing Membrane Volume Calculator | 8.51 gal | |
Wall tiles in the shower roomFloor & Wall Tile CalculatorTiles round the shower room's walls to the tiled height at 600 × 300 mm (about 24 × 12 in), in boxes of eight, with the calculator's straight-lay allowance; the door and the window are not taken off, which covers the cuts round them.
Why this quantity?
Resting on
The pattern waste: the calculator's working figure, a trade convention. | 85 tiles | |
Wall tile adhesiveThinset & Tile Adhesive CalculatorAdhesive over the same walls at the calculator's opening notch, the one a large wall tile takes.
Why this quantity?
Resting on
Change any other figure on the Thinset & Tile Adhesive Calculator | 4 bags | |
Wall tile groutGrout CalculatorGrout for the same walls at the tile row's tile size and the calculator's opening joint; the corners and the joint along the tray are silicone.
Why this quantity?
Resting on
The waste allowance: the calculator's working figure, a trade convention. | 6.29 lb | |
Mist coat or primer on the ceiling and slopeCeiling Paint CalculatorOne sealing coat over the flat ceiling and the slope before the finish: a thinned mist coat on new plaster, a drywall primer on taped board.
Why this quantity?
Resting on
| 0.936 gal | |
Mist coat or primer on the wallsCeiling Paint CalculatorOne sealing coat over the boarded walls and both faces of the partitions, a mist coat on plaster or a primer on taped board, worked as area × coats ÷ spread rate, the same arithmetic on a wall as on a ceiling.
Why this quantity?
Resting on
| 1.8 gal | |
Skirting (baseboard)Baseboard & Trim CalculatorThe room's outer perimeter, the loft's length and the floor's depth twice over, in stock lengths with the calculator's cutting allowance, with no doorway taken off because the doors stand in the new partitions. The skirting along both faces of the partitions, less a doorway on each face for every door, is extra.
Why this quantity?
Resting on
The cutting waste: the calculator's working figure, a trade convention. | 82.5 linear ft | |
Ceiling and slope, two coatsCeiling Paint CalculatorTwo finish coats over the flat ceiling and the slope.
Why this quantity?
Resting on
| 1.87 gal | |
Walls, two coatsCeiling Paint CalculatorTwo finish coats over the same walls and partitions.
Why this quantity?
Resting on
| 3.59 gal | |
Skip (dumpster) for the strip-outSkip & Dumpster Size CalculatorSized on an allowance, not a measurement: a layer 150 mm (6 in) deep over the new floor, for the tiles and battens off the dormer's footprint, the old insulation, the cut rafters and the offcuts, as mixed waste.
Why this quantity?
Resting on
Change any other figure on the Skip & Dumpster Size Calculator | 6.4 yd³ | |
Dust sheets in the rooms belowMasking and Protection Materials CalculatorSheets over the bedrooms and landing under the loft, taken as the new floor's area, and tape round their edges: laying joists and opening the roof drops dust through every gap in the ceiling below.
Why this quantity? | 5 items | |
Scaffold across the backScaffold Face Area and Hire Quantity CalculatorThe back elevation's width at the height of the eaves plus the room height, up to where the dormer's roof is laid; a cover over the opened slope is listed with it.
Why this quantity? | 45 m² of face | |
Deck on the dormer's roofPlywood and OSB Sheet Calculator (Subfloor, Wall and Roof)Full 2440 × 1220 mm (4 × 8 ft) sheets over the dormer's plan, with the calculator's cutting allowance; the firrings under them, where the fall is formed in timber, are listed.
Why this quantity? | 6 sheets (2440x1220 mm) | |
Warm-roof boards on the dormerFoam Board Insulation CalculatorRigid boards over the dormer's deck on the vapour control layer, one layer at the calculator's opening sheet and allowance; the thickness is the energy calculation's, and a second layer is this row again.
Why this quantity? | 6 sheets (2400x1200 mm) | |
EPDM on the dormerEPDM Single-Ply Roofing Roll CalculatorThe dormer's plan area at the calculator's opening roll, a figure to check the sheet against: the dormer is covered from one sheet cut to its width and depth plus the strip turned up under the main roof's tiles at the back and down over the trims at the front and sides.
Why this quantity? | 1 roll | |
Termination bar at the back upstandRoof Perimeter Termination Bar CalculatorBar along the back of the dormer's roof, where the membrane turns up under the main roof's underlay and tiles, with the calculator's allowance; the front and the sides are held by edge trims.
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 length.
Why this quantity? | 19 fasteners | |
Fascia along the dormer's frontFascia Board CalculatorFascia across the dormer's face in stock lengths with the calculator's allowance, raised to clear the warm roof's build-up; the edge trims over it are listed.
Why this quantity? | 2 x 3.6 m boards | |
Breathable membrane on the cheeksRoofing Underlayment CalculatorMembrane over both cheeks behind the tile-hanging, with the calculator's lap allowance, in its 1,000 sq ft (about 93 m²) synthetic rolls; a British breathable membrane comes in smaller rolls, bought by the lapped area in the working. The strip where the main roof's underlay is cut back round the dormer is made good from the same roll.
Why this quantity? | 1 roll | |
Flashing down both cheeksExterior Flashing Layout Trim Sheet CalculatorFlashing where each cheek meets the main roof, the dormer's depth lengthened by the slope factor, both sides, in pieces at the calculator's opening length, a US coil piece. Lead is cut shorter, often with a soaker under every tile course, so set the piece to what you buy.
Why this quantity? | 3 sheets | |
The dormer's own gutterGutter CalculatorGutter across the dormer's face, in stock sections; the working counts the downpipes (downspouts). A dormer draining onto the main roof below takes a short pipe to the lower gutter instead.
Why this quantity? | 2 x 4 m sections | |
Flashing tape round the dormer windowsWindow Opening Flashing Membrane CalculatorSelf-adhered tape round each window in the timber face, sill, jambs and head, with the calculator's run-past and allowances; the windows are items.
Why this quantity? | 14.52 m | |
Studs for the knee wall and the partitionsFraming Stud CalculatorStuds at the calculator's opening centres along the knee wall, the loft's length, and the new partitions, with a king and a jack stud each side of every door. Head and sole plates, about twice the length in timber, are not in the count.
Why this quantity? | 39 studs | |
Boards between and under the sloped raftersFoam Board Insulation CalculatorRigid boards over the sloped ceiling above the knee wall, the area on the slope, at the calculator's opening sheet and allowance, whether they are cut between the rafters or fixed under them; a layer of each is this row twice.
Why this quantity? | 4 sheets (2400x1200 mm) | |
Batts in the knee wall, cheeks and faceMineral Wool Insulation Batt CalculatorBatts between the studs of the knee wall, the two cheeks and the dormer's face less its windows, at the calculator's opening pack and allowance.
Why this quantity? | 6 packages | |
Sound insulation between the floor joistsMineral Wool Insulation Batt CalculatorBatts laid between the new joists over the whole floor before it is decked, for the sound separation a new floor over bedrooms needs.
Why this quantity? | 8 packages | |
Insulation over the flat ceiling beyond the dormerMineral Wool Insulation Batt CalculatorBatts or quilt over the part of the flat ceiling the dormer's warm roof is not above: the strip under the cold void at the ridge, and any strip beside a dormer narrower than the loft, taken as the flat ceiling less the dormer's plan. The thickness is the energy calculation's; a second, cross-laid layer is this row again.
Why this quantity? | 3 packages | |
Plasterboard (drywall) on the ceiling and slopeCeiling Plasterboard (Gypsum Board) Sheet CalculatorBoard over the flat ceiling and the sloped strip, at the calculator's opening sheet and allowance.
Why this quantity? | 14 sheets | |
Plasterboard (drywall) on the wallsCeiling Plasterboard (Gypsum Board) Sheet CalculatorBoard over the knee wall, the face less its windows and the two end walls, the end walls less the triangle under the slope at each, at the same sheet and allowance. The end walls are taken at the room height right back to the face, so the inside of each cheek is already in them and is not boarded twice. An end wall plastered straight onto the masonry is the same area in plaster.
Why this quantity? | 16 sheets | |
Board on both faces of the partitionsMulti-Layer Fire-Rated (Type X) Gypsum Sheet CalculatorOne layer each side of the new partitions, the length by the room height, at the calculator's opening sheet, with nothing added for cutting. Where the partitions enclose the escape, the board and the layers are the ones the fire resistance asks for.
Why this quantity? | 10 sheets | |
Skim over every boardSkim Coat Plaster CalculatorFinish plaster over the ceiling, the slope, the walls and both faces of the partitions, at the calculator's opening thickness and allowance, with the joints scrimmed first.
Why this quantity? | 294.96 kg | |
Tanking in the shower roomCold-Applied Liquid Waterproofing Membrane Volume CalculatorLiquid membrane over the shower room's floor and its walls to the tiled height, at the calculator's opening film and solids; a tanking kit states its own coats and coverage, so set both from its data sheet. The tape at every corner and the collars round the pipes come in the kit.
Why this quantity? | 32.39 L | |
Wall tiles in the shower roomFloor & Wall Tile CalculatorTiles round the shower room's walls to the tiled height at 600 × 300 mm (about 24 × 12 in), in boxes of eight, with the calculator's straight-lay allowance; the door and the window are not taken off, which covers the cuts round them.
Why this quantity? | 86 tiles | |
Wall tile adhesiveThinset & Tile Adhesive CalculatorAdhesive over the same walls at the calculator's opening notch, the one a large wall tile takes.
Why this quantity? | 4 bags | |
Wall tile groutGrout CalculatorGrout for the same walls at the tile row's tile size and the calculator's opening joint; the corners and the joint along the tray are silicone.
Why this quantity? | 2.92 kg | |
Mist coat or primer on the ceiling and slopeCeiling Paint CalculatorOne sealing coat over the flat ceiling and the slope before the finish: a thinned mist coat on new plaster, a drywall primer on taped board.
Why this quantity? | 3.53 L | |
Mist coat or primer on the wallsCeiling Paint CalculatorOne sealing coat over the boarded walls and both faces of the partitions, a mist coat on plaster or a primer on taped board, worked as area × coats ÷ spread rate, the same arithmetic on a wall as on a ceiling.
Why this quantity? | 6.73 L | |
Skirting (baseboard)Baseboard & Trim CalculatorThe room's outer perimeter, the loft's length and the floor's depth twice over, in stock lengths with the calculator's cutting allowance, with no doorway taken off because the doors stand in the new partitions. The skirting along both faces of the partitions, less a doorway on each face for every door, is extra.
Why this quantity? | 25.3 m | |
Ceiling and slope, two coatsCeiling Paint CalculatorTwo finish coats over the flat ceiling and the slope.
Why this quantity? | 7.05 L | |
Walls, two coatsCeiling Paint CalculatorTwo finish coats over the same walls and partitions.
Why this quantity? | 13.47 L | |
Skip (dumpster) for the strip-outSkip & Dumpster Size CalculatorSized on an allowance, not a measurement: a layer 150 mm (6 in) deep over the new floor, for the tiles and battens off the dormer's footprint, the old insulation, the cut rafters and the offcuts, as mixed waste.
Why this quantity? | 4.95 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 in the rooms below1.3 h (0.7–2.6)
- Deck on the dormer's roof2.1 h (1.2–4.2)
- Warm-roof boards on the dormer2.8 h (1.5–7.7)
- EPDM on the dormer3.1 h (1.5–6.1)
- Termination bar at the back upstand1.8 h (1.0–3.5)
- Fascia along the dormer's front4.0 h (2.0–10)
- Breathable membrane on the cheeks0.3 h (0.2–0.7)
- Flashing down both cheeks7.1 h (2.4–14)
- The dormer's own gutter2.0 h (1.0–4.0)
- Flashing tape round the dormer windows8.0 h (2.0–16)
- Studs for the knee wall and the partitions6.5 h (3.6–13)
- Boards between and under the sloped rafters1.7 h (0.9–4.7)
- Batts in the knee wall, cheeks and face2.3 h (1.1–5.0)
- Sound insulation between the floor joists3.3 h (1.6–7.2)
- Insulation over the flat ceiling beyond the dormer1.0 h (0.5–2.2)
- Plasterboard (drywall) on the ceiling and slope4.2 h (2.3–7.8)
- Plasterboard (drywall) on the walls4.8 h (2.7–9.0)
- Board on both faces of the partitions3.2 h (1.8–6.0)
- Joint compound for taping and filling every board16 h (9.1–32)
- Tanking in the shower room3.4 h (1.7–6.8)
- Wall tiles in the shower room15 h (9.7–31)
- Skirting (baseboard)4.5 h (2.5–10)
- Ceiling and slope, two coats6.3 h (3.5–14)
- Walls, two coats12 h (6.7–27)
- Skip (dumpster) for the strip-out4.9 h (2.4–15)
About 122 person-hours in the rows that carry them, between 64 and 259.
Trade by trade
- Labourer1 labourer2 days
- Carpenter2 carpenters1 day
- Roofer2 roofers1 day
- Glazier2 glaziershalf a day
- Drywaller1 drywaller + 1 labourer1 day
- Taper1 taper + 1 labourer1 day
- Waterproofing operative1 waterproofing operativehalf a day
- Tiler1 tiler2 days
- Painter1 painter2½ days
About 11 days, one trade after another at eight hours a day. Left out: drying and curing, deliveries, inspections, trades overlapping.
7 rows carry no hours of their own
- Scaffold across the back: 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 at the back upstand
- Paper joint tape over every board: counted with Joint compound for taping and filling every board
- Wall tile adhesive: counted with Wall tiles in the shower room
- Wall tile grout: counted with Wall tiles in the shower room
- Mist coat or primer on the ceiling and slope: counted with Ceiling and slope, two coats and Walls, two coats
- Mist coat or primer on the walls: counted with Ceiling and slope, two coats and Walls, two coats
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 in the rooms below1.3 h (0.7–2.6)
- Deck on the dormer's roof2.1 h (1.2–4.2)
- Warm-roof boards on the dormer2.7 h (1.5–7.5)
- EPDM on the dormer3.0 h (1.5–6.0)
- Termination bar at the back upstand1.8 h (1.0–3.5)
- Fascia along the dormer's front4.0 h (2.0–10)
- Breathable membrane on the cheeks0.3 h (0.2–0.7)
- Flashing down both cheeks7.0 h (2.3–14)
- The dormer's own gutter2.0 h (1.0–4.0)
- Flashing tape round the dormer windows8.0 h (2.0–16)
- Studs for the knee wall and the partitions6.6 h (3.6–13)
- Boards between and under the sloped rafters1.8 h (1.0–4.9)
- Batts in the knee wall, cheeks and face2.3 h (1.1–5.0)
- Sound insulation between the floor joists3.3 h (1.7–7.3)
- Insulation over the flat ceiling beyond the dormer1.1 h (0.5–2.3)
- Plasterboard (drywall) on the ceiling and slope4.5 h (2.5–8.4)
- Plasterboard (drywall) on the walls5.1 h (2.9–9.6)
- Board on both faces of the partitions3.2 h (1.8–6.0)
- Skim over every board17 h (10–36)
- Tanking in the shower room3.4 h (1.7–6.8)
- Wall tiles in the shower room15 h (9.8–31)
- Skirting (baseboard)4.6 h (2.5–10)
- Ceiling and slope, two coats6.3 h (3.5–14)
- Walls, two coats12 h (6.7–27)
- Skip (dumpster) for the strip-out5.0 h (2.5–15)
About 124 person-hours in the rows that carry them, between 66 and 265.
Trade by trade
- Labourer1 labourer2 days
- Carpenter2 carpenters1 day
- Roofer2 roofers1 day
- Glazier2 glaziershalf a day
- Drywaller1 drywaller + 1 labourer1 day
- Plasterer1 plasterer2 days
- Waterproofing operative1 waterproofing operativehalf a day
- Tiler1 tiler2 days
- Painter1 painter2½ days
About 12½ days, one trade after another at eight hours a day. Left out: drying and curing, deliveries, inspections, trades overlapping.
6 rows carry no hours of their own
- Scaffold across the back: 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 at the back upstand
- Wall tile adhesive: counted with Wall tiles in the shower room
- Wall tile grout: counted with Wall tiles in the shower room
- Mist coat or primer on the ceiling and slope: counted with Ceiling and slope, two coats and Walls, two coats
- Mist coat or primer on the walls: counted with Ceiling and slope, two coats and Walls, two coats
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
A dormer loft (attic) conversion is a new storey built inside a roof that is still keeping the rain off the rooms below, and the order of work follows from that. The scaffold and a cover go up first; the new floor joists and any steel go in while the roof is still whole; then the back slope is opened only for as long as it takes to frame the dormer, deck it and get a waterproof layer on. Nothing inside starts until the dormer is watertight.
The dormer is three surfaces. Its flat roof is built warm, insulation boards on the deck under the waterproofing, so the joists inside stay at room temperature and need no ventilated gap. Its face carries the windows. Its two cheeks, the triangular side walls between the dormer's roof and the main roof, are tile-hung over a breathable membrane to match the roof, and each meets the main roof along a sloping edge that is flashed from top to bottom; that edge is the dormer's depth lengthened by the main roof's slope factor.
Inside, the boarded surfaces are measured from the loft's own shape: the flat ceiling, the slope above the knee wall on the other side of the roof, the knee wall, the dormer's face, and the two end walls, taken at full height right back to the face, so the inside of each cheek is part of them. The heat insulation goes in the slope, the knee wall, the dormer's roof, cheeks and face, and over the flat ceiling wherever the dormer's warm roof is not above it; the floor takes insulation against sound. An end wall that is a gable facing outside needs insulating as well, and a party wall shared with next door does not. The new partitions round the stair are boarded both sides, because they enclose the way out. How the boards are finished follows the units: skimmed in plaster, the usual British finish, when metric is showing, and taped and filled with joint compound, the North American one, when imperial is, with either one choice away.
The parts that decide whether the room can be slept in are the ones this page never measures. The floor joists, the steels and their padstones, the trimmers round the stair opening and the dormer's frame are the engineer's; the stair's rise, going and headroom, the fire doors onto the stair, the alarms and the escape route are set by the building regulations or code where the house is, and building control signs them off. Each is an item here with no quantity. A shower room is optional: give it a size of 0 and its tanking, tiles, adhesive and grout drop out.
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.
- Have the floor, the steels and the dormer designed, lodge the plans or the notice with building control, and serve any party wall notice before the scaffold goes up.
- Scaffold the back of the house with a cover ready over the roof, then clear the loft: the old insulation, any boards, and the cold-water tank if it is going.
- Set the steels on their padstones and lay the new floor joists clear of the ceiling below, before a single rafter is cut.
- Strip the tiles where the dormer goes, prop and cut the rafters, frame the face, the cheeks and the dormer's roof, then deck it and lay the vapour control layer, the insulation and the waterproofing, sheeting the opened slope under the scaffold's cover every night until the waterproofing is on; any rafter, purlin or wall plate found rotten once the tiles are off is repaired before it is built on.
- Membrane, batten and tile-hang the cheeks, dress the flashings where they meet the main roof, fix the fascia and the dormer's gutter, fit the windows, and fit any rooflights in the other slope.
- Trim the stair opening and fit the stair, build the knee wall and the partitions round the escape, and run the cables, the pipes and the shower room's extract duct.
- Insulate the slope, the knee wall, the cheeks, the face and the flat ceiling beyond the dormer's roof, lay sound insulation between the floor joists and deck the floor, then board the room and finish the boards, skimmed in plaster or taped and filled, and tank the shower room once its boards are up.
- Hang the fire doors, fit the handrail, the alarms, the radiator and the shower room, tile it, decorate, lay the floor, and have the electrical test and the completion inspection before the room is used.
What this takeoff does not cover
- The structure: the floor joists, the steels, their padstones and bearings, the trimmers round the stair and the dormer's frame. Each is listed as work with no quantity; the engineer sizes it and building control inspects it.
- The stair and its balustrade, made to the loft's rise and headroom and listed as items. The stair page on this site can check a flight's rise and going, but this page orders no flight.
- Party wall matters: the notices where a steel bears on a party wall or the dormer is built up against one, and any survey or agreement that follows.
- Drainage beyond connecting the shower room to the existing soil stack, a new stack, and whether the boiler or heat pump can take another radiator.
- The tiles on the cheeks and in the made-good slope round the dormer, the cladding on the face beside the windows, and every fixing for them: the cladding and the tiling are listed as work, not measured.
- The floor deck over the new joists, listed as work. A British loft floor is usually decked in tongue-and-groove chipboard 600 mm (2 ft) wide, which the site's sheet page does not count; a US attic floor takes 1220 × 2440 mm (4 × 8 ft) tongue-and-groove sheets, which the plywood page counts over the floor's area.
- Ventilation of the cold roof spaces left behind the knee wall and over the flat ceiling, and the insulation of a gable end wall facing outside.
- The shower room's floor finish, its tray, basin and WC, and the tiling above the height you give.
- Render on the dormer's cheeks or face, where they are rendered rather than tiled or clad, with its primer, mesh and beads. It is not measured here.
- Undercoat and gloss (trim enamel) on the new woodwork: the doors, the architraves (casings) and the rest of the trim. The architraves are not counted, and the paint on the woodwork, with the knotting and priming bare timber needs first, is not measured here.
Quote check
Been given a quote for this job?
Paste it into the loft conversion 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 loft conversion takeoff give for a typical job?
- Opened at Loft length, wall to wall 6 m · New floor, knee wall to dormer face 5.5 m · Sloped ceiling, on plan 1.25 m · Knee wall height 1.2 m · Floor to flat ceiling 2.3 m · Main roof slope factor 1.3 · Dormer width 5 m · Dormer depth, on plan 3 m · Windows in the dormer face 2 · Window width, each 1.2 m · Window height, each 1.2 m · Doors in the new partitions 2 · New stud partitions 6 m · Height of the eaves above the ground 5.2 m · Shower room length (0 if none) 2 m · Shower room width 1.5 m · Tiled height in the shower room 2 m, it orders: Dust sheets in the rooms below, 5 items; Scaffold across the back, 45 m² of face; Deck on the dormer's roof, 6 sheets (2440x1220 mm); Warm-roof boards on the dormer, 6 sheets (2400x1200 mm); EPDM on the dormer, 1 roll; Termination bar at the back upstand, 5.25 m; Termination bar fixings, 19 fasteners; Fascia along the dormer's front, 2 x 3.6 m boards; Breathable membrane on the cheeks, 1 roll; Flashing down both cheeks, 3 sheets; The dormer's own gutter, 2 x 4 m sections; Flashing tape round the dormer windows, 14.5 m; Studs for the knee wall and the partitions, 39 studs; Boards between and under the sloped rafters, 4 sheets (2400x1200 mm); Batts in the knee wall, cheeks and face, 6 packages; Sound insulation between the floor joists, 8 packages; Insulation over the flat ceiling beyond the dormer, 3 packages; Plasterboard (drywall) on the ceiling and slope, 14 sheets; Plasterboard (drywall) on the walls, 16 sheets; Board on both faces of the partitions, 10 sheets; Skim over every board, 295 kg; Tanking in the shower room, 32.4 L; Wall tiles in the shower room, 86 tiles; Wall tile adhesive, 4 bags; Wall tile grout, 2.92 kg; Mist coat or primer on the ceiling and slope, 3.53 L; Mist coat or primer on the walls, 6.73 L; Skirting (baseboard), 25.3 m; Ceiling and slope, two coats, 7.05 L; Walls, two coats, 13.5 L; Skip (dumpster) for the strip-out, 4.95 m³. Opened at Loft length, wall to wall 19.5 ft · New floor, knee wall to dormer face 18 ft · Sloped ceiling, on plan 4 ft · Knee wall height 4 ft · Floor to flat ceiling 7.5 ft · Main roof slope factor 1.3 · Dormer width 16.5 ft · Dormer depth, on plan 10 ft · Windows in the dormer face 2 · Window width, each 4 ft · Window height, each 4 ft · Doors in the new partitions 2 · New stud partitions 19.5 ft · Height of the eaves above the ground 17 ft · Shower room length (0 if none) 6.5 ft · Shower room width 5 ft · Tiled height in the shower room 6.5 ft: Dust sheets in the rooms below, 5 items; Scaffold across the back, 478 ft² of face; Deck on the dormer's roof, 6 sheets (4x8 ft); Warm-roof boards on the dormer, 6 sheets (4x8 ft); EPDM on the dormer, 1 roll; Termination bar at the back upstand, 17.3 ft; Termination bar fixings, 19 fasteners; Fascia along the dormer's front, 2 x 12 ft boards; Breathable membrane on the cheeks, 1 roll; Flashing down both cheeks, 3 sheets; The dormer's own gutter, 2 x 10 ft sections; Flashing tape round the dormer windows, 48.4 ft; Studs for the knee wall and the partitions, 39 studs; Boards between and under the sloped rafters, 4 sheets (4x8 ft); Batts in the knee wall, cheeks and face, 6 packages; Sound insulation between the floor joists, 8 packages; Insulation over the flat ceiling beyond the dormer, 3 packages; Plasterboard (drywall) on the ceiling and slope, 13 sheets; Plasterboard (drywall) on the walls, 15 sheets; Board on both faces of the partitions, 10 sheets; Joint compound for taping and filling every board, 3 x 4.5 gal boxes; Paper joint tape over every board, 629 ft; Tanking in the shower room, 8.51 gal; Wall tiles in the shower room, 85 tiles; Wall tile adhesive, 4 bags; Wall tile grout, 6.29 lb; Mist coat or primer on the ceiling and slope, 0.94 gal; Mist coat or primer on the walls, 1.8 gal; Skirting (baseboard), 82.5 linear ft; Ceiling and slope, two coats, 1.87 gal; Walls, two coats, 3.59 gal; Skip (dumpster) for the strip-out, 6.4 yd³. Every figure follows the dimensions you give it.
- Which calculators does the loft conversion takeoff run?
- 25 calculators, for 32 lines: Masking and Protection Materials Calculator, Scaffold Face Area and Hire Quantity Calculator, Plywood and OSB Sheet Calculator (Subfloor, Wall and Roof), Foam Board Insulation Calculator, EPDM Single-Ply Roofing Roll Calculator, Roof Perimeter Termination Bar Calculator, Roof Membrane Termination Bar Fastener Calculator, Fascia Board Calculator, Roofing Underlayment Calculator, Exterior Flashing Layout Trim Sheet Calculator, Gutter Calculator, Window Opening Flashing Membrane Calculator, Framing Stud Calculator, Mineral Wool Insulation Batt Calculator, Ceiling Plasterboard (Gypsum Board) Sheet Calculator, Multi-Layer Fire-Rated (Type X) Gypsum Sheet Calculator, Drywall Joint Compound Calculator, Drywall Joint Tape Calculator, Cold-Applied Liquid Waterproofing Membrane Volume Calculator, Floor & Wall Tile Calculator, Thinset & Tile Adhesive Calculator, Grout Calculator, Ceiling Paint Calculator, Baseboard & Trim 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.24 calculators, for 31 lines: Masking and Protection Materials Calculator, Scaffold Face Area and Hire Quantity Calculator, Plywood and OSB Sheet Calculator (Subfloor, Wall and Roof), Foam Board Insulation Calculator, EPDM Single-Ply Roofing Roll Calculator, Roof Perimeter Termination Bar Calculator, Roof Membrane Termination Bar Fastener Calculator, Fascia Board Calculator, Roofing Underlayment Calculator, Exterior Flashing Layout Trim Sheet Calculator, Gutter Calculator, Window Opening Flashing Membrane Calculator, Framing Stud Calculator, Mineral Wool Insulation Batt Calculator, Ceiling Plasterboard (Gypsum Board) Sheet Calculator, Multi-Layer Fire-Rated (Type X) Gypsum Sheet Calculator, Skim Coat Plaster Calculator, Cold-Applied Liquid Waterproofing Membrane Volume Calculator, Floor & Wall Tile Calculator, Thinset & Tile Adhesive Calculator, Grout Calculator, Ceiling Paint Calculator, Baseboard & Trim 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 loft conversion takeoff leave out?
- 10 things, each named on this page: The structure; The stair and its balustrade, made to the loft's rise and headroom and listed as items; Party wall matters; Drainage beyond connecting the shower room to the existing soil stack, a new stack, and whether the boiler or heat pump can take another radiator; The tiles on the cheeks and in the made-good slope round the dormer, the cladding on the face beside the windows, and every fixing for them; The floor deck over the new joists, listed as work; Ventilation of the cold roof spaces left behind the knee wall and over the flat ceiling, and the insulation of a gable end wall facing outside; The shower room's floor finish, its tray, basin and WC, and the tiling above the height you give; Render on the dormer's cheeks or face, where they are rendered rather than tiled or clad, with its primer, mesh and beads; Undercoat and gloss (trim enamel) on the new woodwork.
- Can I check a quote for this job against the takeoff?
- Yes. The loft conversion 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.