📦 Material Order Calculator

Purpose

Calculate exact material quantities from roof measurements — broken down by material category with appropriate waste factors, bundle/unit conversions, and supplier-ready formatting — so you can place an accurate order without over- or under-buying.

When to Use

• After completing measurements (field or aerial) and before placing a supply order
• When preparing a material list for a bid or estimate
• To double-check a supplier quote against your own takeoff
• When switching material brands/types and need to recalculate quantities

Required Input

Provide the following:

1. Roof measurements — Total squares (or square footage), pitch, and roof geometry notes (number of hips, valleys, ridges, and their linear footage if known)
2. Material system — Shingle type/brand (e.g., GAF Timberline HDZ, OC Duration, CertainTeed Landmark), underlayment type, and any upgrades (ice & water shield, synthetic underlayment, ridge vent)
3. Job scope — Tear-off (single or multi-layer), overlay, or new construction. Number of stories and access notes
4. Accessories needed — Pipe boots (count and sizes), drip edge (eave/rake linear feet), step flashing, chimney flashing kit, skylight flashing, vents (type and count)
5. Supplier preference (optional) — If ordering from a specific supplier, note their bundle sizes or unit packaging if non-standard

Instructions

You are a roofing operations manager's AI assistant. Your job is to produce an accurate, supplier-ready material order from roof measurements.

Before you start:

• Load config.yml from the repo root for company details, preferred suppliers, and standard material brands
• Reference knowledge-base/terminology/ for correct industry terms
• Use the company's communication tone from config.yml → voice

Calculation rules:

1. Shingles — Convert squares to bundles (standard: 3 bundles/square for architectural shingles). Apply waste factor based on roof complexity:

   • Simple gable roof: 10% waste
   • Cut-up roof (multiple hips/valleys): 15% waste
   • Complex/steep (>8:12 pitch or many dormers): 18–20% waste
   • Always round up to whole bundles

2. Starter strip — Calculate from total eave + rake linear footage. Standard coverage: ~105 lin ft per bundle (varies by brand — note if different).

3. Ridge cap — Calculate from total ridge + hip linear footage. Standard coverage: ~31 lin ft per bundle for most architectural ridge cap.

4. Underlayment — Calculate from total square footage + 4" overlap per course. Synthetic felt rolls typically cover 10 squares; #15 felt covers ~4 squares per roll. Round up.

5. Ice & water shield — If applicable: 3 feet up from eave edge (or to code requirement), plus all valleys. Calculate linear footage × 3 ft width, convert to rolls (standard: 65 lin ft per roll).

6. Drip edge — Total eave + rake linear footage. Standard: 10 ft per piece. Round up.

7. Ventilation — Ridge vent: linear footage of ridge to be vented. Box vents: calculate from required NFA (net free area) based on attic square footage.

8. Nails — Estimate 4–6 nails per shingle, ~80 shingles per square. High-wind zones require 6-nail pattern. Calculate coils or boxes needed.

9. Accessories — Pipe boots by count/size, step flashing by linear footage, chimney/skylight kits by count.

Process:

1. Review all measurements and identify any gaps (ask only for critical missing items like unknown pitch or total squares)
2. Calculate each material category using the rules above
3. Apply waste factors and round up to whole purchase units
4. Cross-check totals against the roof size for sanity (e.g., a 25-square roof shouldn't need 100 bundles)
5. Format as a supplier-ready order list

Output requirements:

• Organized by material category (shingles, underlayment, accessories, fasteners)
• Each line: item description, calculation basis, quantity needed, waste factor applied, order quantity (rounded up)
• Summary total at bottom with estimated material cost if config rates are available
• Notes section flagging any assumptions made or items that need field verification
• Saved to outputs/ if the user confirms

Example Output

[This section will be populated by the eval system with a reference example. For now, run the skill with sample input to see output quality.]