Pricing Model

Pitch Roofing — Correct as of 24 March 2026, 18:30 GMT

This document describes exactly how Pitch calculates a roofing quote. A customer describes their job in plain English, an LLM selects items from a fixed-price catalog, and deterministic code turns those selections into a quoted price. The LLM cannot invent prices — it can only pick from the catalog below.

The pipeline: Catalog lookup → Pitch adjustment → Labour/material split → Regional adjustment → Minimum floor → Margin → VAT → Round to £100

1. The Task Catalog

Every line item in a quote maps to one of these catalog entries. Prices are ex-VAT, before any adjustments. Items marked with tiers require the LLM to select the appropriate size/severity.

Item	Unit	Price / Tiers
Roofing Work
Strip & reroof (concrete tile)	per sqm	£67
Strip & reroof (natural slate)	per sqm	£130
Strip & reroof (clay tile)	per sqm	£100
Flat roof replacement (EPDM)	per sqm	£85
Tile/slate repair	flat	minor £150 · moderate £550 · extensive £1,200
Ridge tile repointing	per m	£40
Valley repair/replacement	each	£350
Flashing renewal	flat	chimney £300 · wall £200 · step £250
Velux/roof window re-seal	each	£175
Velux/roof window installation	each	£1,200
Flat skylight re-seal	each	£150
Flat skylight installation	each	£800
Felt/membrane patch repair	each	£200
Lead work repair	flat	small £200 · medium £450 · large £800
Structural timber repair	flat	minor £300 · moderate £600 · major £1,000
Boarding/decking renewal	per sqm	£25
Chimney
Chimney repointing	flat	small £400 · medium £600 · large £800
Chimney cowl/cap	each	£120
Chimney stack rebuild	flat	partial £800 · full £1,500
Guttering & Drainage
Guttering replacement	per m	£35
Gutter repair (section)	each	£100
Fascia & soffit replacement	per m	£95
Downpipe replacement	each	£80
Access & Overhead
Scaffolding	flat	bungalow £500 · terraced £800 · semi £1,000 · detached £1,800 · tall £2,200
Skip & waste removal	flat	small £100 · standard £300 · large £450
Solar
Solar panel removal & refit	flat	£1,500

Prices benchmarked against Checkatrade, MyBuilder, HomeHow, and FMB pricing guides (March 2026). "Flat" unit means a single charge regardless of quantity.

2. How a Price Is Calculated

Once the LLM selects catalog items (with quantities and tiers), deterministic code runs through these steps. No randomness, no LLM involvement in the maths.

Look up the unit price

For each selected item, fetch the base price from the catalog. If the item has tiers (e.g. tile repair: minor/moderate/extensive), use the tier the LLM selected.

Apply pitch area factor (per-sqm items only)

For items priced per square metre (reroofing, boarding), multiply by a pitch factor that accounts for the roof's slope increasing the actual surface area. This comes from Ordnance Survey data about the property's roof shape.

Roof Type	OS Shape	Area Factor	Labour Factor
Flat roof	Flat	×1.02	×1.00
Standard pitch (~30°)	Pitched, Mixed, Unknown	×1.15	×1.05
Steep (~40°)	future	×1.25	×1.20
Very steep (45°+)	future	×1.40	×1.40

Currently most properties map to "Medium" (standard pitched roof). Steep/very steep tiers exist in the model but aren't yet populated from data — they're available for manual override or future data sources.

Split into labour and material/hire

Rather than applying the regional adjustment to the full price (which would over-inflate material costs in expensive regions), we split each line item:

Work Items

Roofing, repairs, chimney, guttering, solar

Material = 40% of base cost (fixed nationally) Labour = 60% of base cost (adjusted by region + pitch)

Access Items

Scaffolding, skip hire

Hire cost = 70% of base cost (fixed nationally) Labour = 30% of base cost (adjusted by region only)

Rationale: materials and equipment hire are priced nationally. Only labour varies by region. The 60/40 split is the industry standard for roofing work. Access items are mostly hire costs with less labour, hence 30/70.

Apply regional multiplier (to labour portion only)

The customer's postcode maps to a region. The multiplier adjusts the labour portion to reflect local trade rates.

Region	Multiplier	Effective on Work Items	Effective on Access Items
London	1.35	×1.21	×1.105
South East England	1.20	×1.12	×1.06
South West England	1.10	×1.06	×1.03
East of England	1.05	×1.03	×1.015
East Midlands	1.00	×1.00	×1.00
West Midlands	1.00	×1.00	×1.00
North West England	0.95	×0.97	×0.985
Yorkshire & The Humber	0.95	×0.97	×0.985
North East England	0.90	×0.94	×0.97
Wales	0.90	×0.94	×0.97
Scotland	0.95	×0.97	×0.985

"Effective" columns show the total multiplier on the full item price after the labour/material split. E.g. London work items: 0.40 + (0.60 × 1.35) = 1.21 total, not 1.35.

Sum line items & enforce minimum

All line item costs are summed. If the total is below £250, it's raised to £250. This prevents unrealistically small quotes for minor repairs — real roofers have minimum call-out charges of £200–300.

Apply margins

Two prices are generated from the subtotal:

Base price — subtotal × 1.15 (15% margin). This is the "from" price shown to the customer.
Fixed price — subtotal × 1.28 (28% margin). This is the guaranteed fixed price. The extra 13% covers risk of overruns, payment processing, and our profit.

Both are rounded to the nearest £100 (ex-VAT).

Add VAT

20% VAT is added to the fixed price, then rounded to the nearest £100 for the final customer-facing number.

3. Worked Examples

Example A: Full reroof of a semi-detached in London

Concrete tile, pitched roof, 55 sqm. LLM selects: reroof-concrete (55 sqm), scaffolding (semi), skip (standard).

Line item breakdown

Reroof concrete — 55 sqm, pitched roof, London

Base: £67 × 55 sqm × 1.15 pitch area£4,242.25

Material (40%)£1,696.90

Labour (60% × 1.35 region × 1.05 pitch)£3,608.89

Line item cost£5,306

Scaffolding (semi) — London

Base: £1,000£1,000.00

Hire (70%)£700.00

Labour (30% × 1.35 region)£405.00

Line item cost£1,105

Skip (standard) — London

Base: £300£300.00

Hire (70%)£210.00

Labour (30% × 1.35 region)£121.50

Line item cost£332

Subtotal£6,743

Base price (×1.15, round to £100)£7,800 ex-VAT

Fixed price (×1.28, round to £100)£8,600 ex-VAT

VAT (20%)£1,720

Customer sees: from £9,400 — fixed at £10,400 inc VAT

Checkatrade benchmark for full concrete reroof on a London semi: £8,000–15,000 inc VAT. Our quote sits in the lower-middle of that range.

Example B: Minor tile repair in Wales

Pitched roof. LLM selects: tile-repair (minor), scaffolding (terraced).

Line item breakdown

Tile repair (minor) — Wales

Base: £150 (flat item, no area factor)£150.00

Material (40%)£60.00

Labour (60% × 0.90 region × 1.05 pitch)£85.05

Line item cost£145

Scaffolding (terraced) — Wales

Base: £800£800.00

Hire (70%)£560.00

Labour (30% × 0.90 region)£216.00

Line item cost£776

Raw subtotal£921

Minimum floor (£250)not triggered

Fixed price (×1.28, round to £100)£1,200 ex-VAT

VAT (20%)£240

Customer sees: fixed at £1,400 inc VAT

Example C: Small repair — minimum floor in action

Gutter repair only, no scaffolding needed (ground-floor access). East Midlands.

Line item breakdown

Gutter repair (section) — East Midlands

Base: £100£100.00

Material (40%)£40.00

Labour (60% × 1.00 region × 1.05 pitch)£63.00

Line item cost£103

Raw subtotal£103

Minimum floor applied (£250)£250

Fixed price (×1.28, round to £100)£300 ex-VAT

VAT (20%)£60

Customer sees: fixed at £400 inc VAT

Without the £250 floor, this would have quoted £200 inc VAT — below what any roofer would actually charge for a call-out.

4. What's Not Yet in the Model

Things we know matter but haven't yet built:

Steep/very steep pitch detection — the multipliers exist but we can't yet detect pitch angle from OS data. Most UK roofs are 30–35° so the "Medium" default is usually correct.
Conservation area surcharges — listed buildings and conservation areas often require more expensive materials (natural slate vs concrete). Not yet factored.
Seasonal demand — roofing peaks Sept–March. Could affect lead times or pricing in future.
Feedback loops — once live, we can track quote-to-contact conversion and roofer acceptance rates to continuously recalibrate prices.

5. Price Sources & Confidence

Base catalog prices were benchmarked against:

Checkatrade cost guides (2025–2026)
MyBuilder price guides
HomeHow cost guides
Federation of Master Builders (FMB) pricing guides
MyJobQuote cost comparisons

Region multipliers are directionally aligned with BCIS location factors (the construction industry standard), though not directly sourced from the BCIS subscription dataset. Labour/material split ratios use the industry-standard 60/40 for roofing work.

Confidence level: reasonable estimates, not precise. Base prices carry ±20–30% uncertainty vs actual market rates. The model will improve significantly once we have real quote-to-completion data.