Strip and re-tile a pitched roof: calculator for UK builders
Answer the measurements this calculation needs and JobBosh works out the materials with wastage and pack rounding, the labour hours by role, the plant, the waste and the site needs - then prices them from your own figures, a supplier's quotation or a dated price you record. Free, no account needed to start.
What it works out
- Material: Concrete interlocking tiles; Treated graded battens 25 x 50 mm; Breathable roofing membrane; Dry ridge / hip system; Nails, clips, eaves protection, ventilation
- Labour: Strip existing covering and battens; Membrane, batten and tile
- Waste: Old tiles, battens, felt
The questions it asks
| Question | Unit / choices | Required? | Help |
|---|---|---|---|
| Roof area (on the slope) | m2 | required | Plan area / cos(pitch); a 35 degree pitch is x 1.22. |
| New tile | one of: concrete interlocking, clay plain, slate natural, slate fibre cement | optional - default concrete_interlocking (labelled assumed) | |
| Re-use existing tiles? | yes / no | optional - default no (labelled assumed) | |
| Ridge + hip length | m | required | |
| Storeys | nr | optional - default 2 (labelled assumed) |
The norms behind it, with their sources
Coverage, productivity and wastage defaults you can edit; each carries where it comes from and is shown as assumed until your own benchmark replaces it.
| Norm | Value | Source | Tier |
|---|---|---|---|
| Concrete interlocking tiles per m2 | 10 nr/m2 | typical manufacturer figure (varies 9.7-10.4) | assumed |
| Plain tiles per m2 at 100 mm gauge | 60 nr/m2 | typical manufacturer figure | assumed |
| 500 x 250 slates per m2 | 20 nr/m2 | typical | assumed |
| Batten per m2 at 343 mm gauge | 3 m/m2 | typical | assumed |
| Batten per m2 at 100 mm gauge | 10 m/m2 | typical | assumed |
| Breathable membrane incl. laps | 1.15 m2/m2 | 150 mm laps | assumed |
| Strip roof per m2 | 0.25 hr/m2 | trade practice | assumed |
| Felt, batten and tile per m2 (interlocking) | 0.6 hr/m2 | trade practice | assumed |
| Felt, batten and tile per m2 (plain tiles / slate) | 1.4 hr/m2 | trade practice | assumed |
A worked example
Answers used: Roof area (on the slope) 20 m2; New tile concrete interlocking; Re-use existing tiles? no; Ridge + hip length 4 m; Storeys 2 nr. These are the recipe's own quantities for those answers - the prices are yours, the supplier's or a quotation's, never a figure typed on a web page.
| Kind | Line | Quantity | How it is worked out |
|---|---|---|---|
| material | Concrete interlocking tiles | 210 nr 210 x nr - each (pallets) | 20 m2 x 10 per m2 |
| material | Treated graded battens 25 x 50 mm | 66 m 14 x length - 4.8 m lengths | 20 m2 x 3 m/m2 |
| material | Breathable roofing membrane | 23 m2 1 x roll - 50 m2 rolls | 20 m2 x 1.15 |
| material | Dry ridge / hip system | 4.2 m 1 x pack - 6 m kits | 4 m |
| material | Nails, clips, eaves protection, ventilation | 1 item | one allowance per roof |
| labour | Strip existing covering and battens | 5 hr | 20 m2 x 0.25 h/m2 |
| labour | Membrane, batten and tile | 12 hr | 20 m2 x 0.6 h/m2 |
| waste | Old tiles, battens, felt | 1.2 m3 | 20 m2 x 0.06 m3/m2 |
Labour on this example: about 17 hours across the roles; at your rates it becomes money.
Site questions this work raises: Access equipment and temporary works, Parking and traffic, Site access and neighbours, Waste, Protection and cleanliness.
Specialists or hire it may need, drafted as enquiries from the job's facts: Scaffolding, Waste removal (man and van / clearance), Materials (merchant) delivery.
Scaffold with edge protection is required for a re-roof: by quotation.
Skips: tile waste is heavy - a builder's skip, not a general one.
Then what
Price the lines from your crew rates and your material prices (each with its source and date), answer the site questions (parking, skip, welfare, power, water, protection), let JobBosh draft the supplier enquiries you approve, and issue a branded quotation your customer accepts on a secure link. Guest work is kept for 14 days; a free account keeps it for good.