MCPInstall

ifc-qto-extraction

Extract quantities from IFC/Revit models for quantity takeoff. Uses DDC converters to get element counts, areas, volumes, lengths with grouping and reporting.

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Install

Works with every agent the skills CLI supports.

npx skills add https://github.com/datadrivenconstruction/ddc_skills_for_ai_agents_in_construction --skill ifc-qto-extraction
  1. 01

    Install

    Run the command in your project. The CLI asks which agents to install for.

  2. 02

    Describe the task

    Ask your agent for something this skill covers. It loads ifc-qto-extraction automatically when relevant.

  3. 03

    Review the result

    The agent follows the SKILL.md steps, scripts and references bundled with the skill.

SKILL.md

The instructions your agent reads when the skill is triggered.

IFC Quantity Takeoff Extraction

Extract structured quantity data from BIM models (IFC, Revit) for cost estimation, material ordering, and progress tracking.

Business Case

Problem: Manual quantity takeoff is:

  • Time-consuming (40-80 hours for medium project)
  • Error-prone (human counting mistakes)
  • Not repeatable (changes require full rework)
  • Disconnected from design (no live updates)

Solution: Automated QTO from BIM that:

  • Extracts all quantities in minutes
  • Groups by type, level, zone
  • Updates instantly with model changes
  • Exports to Excel for pricing

ROI: 90% reduction in QTO time, near-zero counting errors

DDC Tools Used

┌──────────────────────────────────────────────────────────────────────┐
│                      QTO EXTRACTION PIPELINE                          │
├──────────────────────────────────────────────────────────────────────┤
│                                                                       │
│   INPUT                 CONVERT                 ANALYZE               │
│   ┌─────────┐          ┌─────────┐            ┌─────────┐            │
│   │ .rvt    │          │ DDC     │            │ Python  │            │
│   │ .ifc    │─────────►│Converter│───────────►│ pandas  │            │
│   │ .dwg    │          │         │            │         │            │
│   └─────────┘          └─────────┘            └─────────┘            │
│                              │                      │                 │
│                              ▼                      ▼                 │
│                        ┌─────────┐            ┌─────────┐            │
│                        │ .xlsx   │            │ Grouped │            │
│                        │ raw data│            │ QTO     │            │
│                        └─────────┘            └─────────┘            │
│                                                    │                  │
│   OUTPUT                                           ▼                  │
│   ┌─────────────────────────────────────────────────────────────┐   │
│   │  QTO Report                                                  │   │
│   │  • Element counts by type                                    │   │
│   │  • Areas (m², ft²)                                           │   │
│   │  • Volumes (m³, ft³)                                         │   │
│   │  • Lengths (m, ft)                                           │   │
│   │  • Weights (kg, tons)                                        │   │
│   │  • Grouped by level/zone/system                              │   │
│   └─────────────────────────────────────────────────────────────┘   │
│                                                                       │
└──────────────────────────────────────────────────────────────────────┘

CLI Commands

Revit to Excel (with BBox for volumes)

# Basic extraction
RvtExporter.exe "C:\Models\Building.rvt"

# Full extraction with bounding boxes (for volume calculations)
RvtExporter.exe "C:\Models\Building.rvt" complete bbox

# Include schedules (Revit's built-in QTO)
RvtExporter.exe "C:\Models\Building.rvt" complete bbox schedule

IFC to Excel

# Extract IFC data
IfcExporter.exe "C:\Models\Building.ifc"

# Output: Building.xlsx with all IFC entities

DWG to Excel (2D areas)

# Extract DWG blocks and areas
DwgExporter.exe "C:\Drawings\FloorPlan.dwg"

Python Implementation

import pandas as pd
import numpy as np
from pathlib import Path
import subprocess
from typing import List, Dict, Optional
from dataclasses import dataclass

@dataclass
class QuantityItem:
    """Single quantity line item"""
    category: str
    type_name: str
    count: int
    area: float = 0.0
    volume: float = 0.0
    length: float = 0.0
    weight: float = 0.0
    unit_area: str = "m²"
    unit_volume: str = "m³"
    unit_length: str = "m"
    level: str = ""
    zone: str = ""


class BIMQuantityExtractor:
    """Extract quantities from BIM models using DDC converters"""

    def __init__(self, converter_path: str):
        self.converter_path = Path(converter_path)

    def convert_model(self, model_path: str, options: List[str] = None) -> Path:
        """Convert BIM model to Excel"""

        model = Path(model_path)
        options = options or ["complete", "bbox"]

        # Determine converter
        ext = model.suffix.lower()
        converters = {
            '.rvt': 'RvtExporter.exe',
            '.rfa': 'RvtExporter.exe',
            '.ifc': 'IfcExporter.exe',
            '.dwg': 'DwgExporter.exe',
            '.dgn': 'DgnExporter.exe'
        }

        converter = self.converter_path / converters.get(ext, 'RvtExporter.exe')

        # Build command
        cmd = [str(converter), str(model)] + options

        # Execute
        result = subprocess.run(cmd, capture_output=True, text=True)

        if result.returncode != 0:
            raise RuntimeError(f"Conversion failed: {result.stderr}")

        # Return path to generated Excel
        xlsx_path = model.with_suffix('.xlsx')
        return xlsx_path

    def load_bim_data(self, xlsx_path: str) -> pd.DataFrame:
        """Load converted BIM data from Excel"""

        xlsx = Path(xlsx_path)
        if not xlsx.exists():
            raise FileNotFoundError(f"Excel file not found: {xlsx}")

        # Read main data sheet
        df = pd.read_excel(xlsx, sheet_name=0)

        # Clean column names
        df.columns = df.columns.str.strip()

        return df

    def extract_quantities(
        self,
        df: pd.DataFrame,
        group_by: str = "Type Name",
        include_categories: List[str] = None
    ) -> List[QuantityItem]:
        """Extract quantities grouped by type"""

        # Filter categories if specified
        if include_categories and 'Category' in df.columns:
            df = df[df['Category'].isin(include_categories)]

        # Group and aggregate
        quantities = []

        for (category, type_name), group in df.groupby(['Category', group_by]):
            item = QuantityItem(
                category=str(category),
                type_name=str(type_name),
                count=len(group)
            )

            # Extract area
            area_cols = ['Area', 'Surface Area', 'Gross Area', 'Net Area']
            for col in area_cols:
                if col in group.columns:
                    item.area = group[col].sum()
                    break

            # Extract volume
            vol_cols = ['Volume', 'Gross Volume', 'Net Volume']
            for col in vol_cols:
                if col in group.columns:
                    item.volume = group[col].sum()
                    break

            # Extract length
            len_cols = ['Length', 'Curve Length', 'Unconnected Height']
            for col in len_cols:
                if col in group.columns:
                    item.length = group[col].sum()
                    break

            # Extract level if available
            if 'Level' in group.columns:
                levels = group['Level'].dropna().unique()
                item.level = ', '.join(str(l) for l in levels)

            quantities.append(item)

        return quantities

    def extract_by_level(
        self,
        df: pd.DataFrame,
        group_by: str = "Type Name"
    ) -> Dict[str, List[QuantityItem]]:
        """Extract quantities grouped by level"""

        result = {}

        if 'Level' not in df.columns:
            result['All Levels'] = self.extract_quantities(df, group_by)
            return result

        for level, level_df in df.groupby('Level'):
            level_name = str(level) if pd.notna(level) else 'Unassigned'
            result[level_name] = self.extract_quantities(level_df, group_by)

        return result

    def calculate_concrete_quantities(self, df: pd.DataFrame) -> dict:
        """Calculate concrete quantities for typical elements"""

        concrete_categories = [
            'Floors', 'Structural Floors',
            'Walls', 'Structural Walls',
            'Structural Foundations', 'Foundation',
            'Structural Columns', 'Columns',
            'Structural Framing', 'Beams'
        ]

        concrete_df = df[df['Category'].isin(concrete_categories)]

        return {
            'total_volume_m3': concrete_df['Volume'].sum() if 'Volume' in concrete_df.columns else 0,
            'by_category': concrete_df.groupby('Category')['Volume'].sum().to_dict() if 'Volume' in concrete_df.columns else {},
            'element_count': len(concrete_df)
        }

    def calculate_wall_quantities(self, df: pd.DataFrame) -> dict:
        """Calculate wall quantities"""

        wall_categories = ['Walls', 'Basic Wall', 'Curtain Wall']
        walls = df[df['Category'].isin(wall_categories)]

        result = {
            'total_area_m2': 0,
            'total_length_m': 0,
            'by_type': {}
        }

        if 'Area' in walls.columns:
            result['total_area_m2'] = walls['Area'].sum()

        if 'Length' in walls.columns:
            result['total_length_m'] = walls['Length'].sum()

        if 'Type Name' in walls.columns:
            for type_name, group in walls.groupby('Type Name'):
                result['by_type'][type_name] = {
                    'count': len(group),
                    'area': group['Area'].sum() if 'Area' in group.columns else 0,
                    'length': group['Length'].sum() if 'Length' in group.columns else 0
                }

        return result

    def generate_qto_report(
        self,
        quantities: List[QuantityItem],
        output_path: str,
        project_name: str = "Project"
    ) -> str:
        """Generate QTO Excel report"""

        # Convert to DataFrame
        records = []
        for q in quantities:
            records.append({
                'Category': q.category,
                'Type': q.type_name,
                'Count': q.count,
                'Area (m²)': round(q.area, 2),
                'Volume (m³)': round(q.volume, 3),
                'Length (m)': round(q.length, 2),
                'Level': q.level
            })

        df = pd.DataFrame(records)

        # Sort by category and type
        df = df.sort_values(['Category', 'Type'])

        # Write to Excel with formatting
        with pd.ExcelWriter(output_path, engine='openpyxl') as writer:
            # Summary sheet
            summary = df.groupby('Category').agg({
                'Count': 'sum',
                'Area (m²)': 'sum',
                'Volume (m³)': 'sum',
                'Length (m)': 'sum'
            }).round(2)
            summary.to_excel(writer, sheet_name='Summary')

            # Detail sheet
            df.to_excel(writer, sheet_name='Detail', index=False)

            # By Level sheet
            if 'Level' in df.columns and df['Level'].notna().any():
                level_summary = df.groupby(['Level', 'Category']).agg({
                    'Count': 'sum',
                    'Area (m²)': 'sum',
                    'Volume (m³)': 'sum'
                }).round(2)
                level_summary.to_excel(writer, sheet_name='By Level')

        return output_path

    def generate_html_report(
        self,
        quantities: List[QuantityItem],
        output_path: str,
        project_name: str = "Project"
    ) -> str:
        """Generate interactive HTML QTO report"""

        # Group by category
        by_category = {}
        for q in quantities:
            if q.category not in by_category:
                by_category[q.category] = []
            by_category[q.category].append(q)

        # Calculate totals
        total_count = sum(q.count for q in quantities)
        total_area = sum(q.area for q in quantities)
        total_volume = sum(q.volume for q in quantities)

        html = f"""
<!DOCTYPE html>
<html>
<head>
    <title>QTO Report - {project_name}</title>
    <style>
        body {{ font-family: Arial, sans-serif; margin: 20px; }}
        .header {{ background: #2c3e50; color: white; padding: 20px; margin-bottom: 20px; }}
        .summary {{ display: flex; gap: 20px; margin-bottom: 20px; }}
        .summary-card {{ background: #ecf0f1; padding: 15px; border-radius: 5px; flex: 1; }}
        .summary-card h3 {{ margin: 0 0 10px 0; color: #7f8c8d; font-size: 14px; }}
        .summary-card .value {{ font-size: 24px; font-weight: bold; color: #2c3e50; }}
        table {{ width: 100%; border-collapse: collapse; margin-bottom: 20px; }}
        th {{ background: #34495e; color: white; padding: 10px; text-align: left; }}
        td {{ padding: 8px; border-bottom: 1px solid #ddd; }}
        tr:hover {{ background: #f5f5f5; }}
        .category-header {{ background: #3498db; color: white; font-weight: bold; }}
        .number {{ text-align: right; }}
    </style>
</head>
<body>
    <div class="header">
        <h1>Quantity Takeoff Report</h1>
        <p>Project: {project_name}</p>
    </div>

    <div class="summary">
        <div class="summary-card">
            <h3>Total Elements</h3>
            <div class="value">{total_count:,}</div>
        </div>
        <div class="summary-card">
            <h3>Total Area</h3>
            <div class="value">{total_area:,.2f} m²</div>
        </div>
        <div class="summary-card">
            <h3>Total Volume</h3>
            <div class="value">{total_volume:,.3f} m³</div>
        </div>
        <div class="summary-card">
            <h3>Categories</h3>
            <div class="value">{len(by_category)}</div>
        </div>
    </div>

    <table>
        <thead>
            <tr>
                <th>Category / Type</th>
                <th class="number">Count</th>
                <th class="number">Area (m²)</th>
                <th class="number">Volume (m³)</th>
                <th class="number">Length (m)</th>
            </tr>
        </thead>
        <tbody>
"""

        for category, items in sorted(by_category.items()):
            cat_count = sum(i.count for i in items)
            cat_area = sum(i.area for i in items)
            cat_volume = sum(i.volume for i in items)

            html += f"""
            <tr class="category-header">
                <td>{category}</td>
                <td class="number">{cat_count:,}</td>
                <td class="number">{cat_area:,.2f}</td>
                <td class="number">{cat_volume:,.3f}</td>
                <td class="number">-</td>
            </tr>
"""
            for item in sorted(items, key=lambda x: x.type_name):
                html += f"""
            <tr>
                <td>&nbsp;&nbsp;&nbsp;{item.type_name}</td>
                <td class="number">{item.count:,}</td>
                <td class="number">{item.area:,.2f}</td>
                <td class="number">{item.volume:,.3f}</td>
                <td class="number">{item.length:,.2f}</td>
            </tr>
"""

        html += """
        </tbody>
    </table>
</body>
</html>
"""

        with open(output_path, 'w', encoding='utf-8') as f:
            f.write(html)

        return output_path


# Usage Example
def extract_qto_from_model(
    model_path: str,
    converter_path: str,
    output_dir: str = None
) -> dict:
    """Complete QTO extraction workflow"""

    from datetime import datetime

    extractor = BIMQuantityExtractor(converter_path)

    # Convert model
    print(f"Converting: {model_path}")
    xlsx_path = extractor.convert_model(model_path, ["complete", "bbox"])

    # Load data
    print(f"Loading data from: {xlsx_path}")
    df = extractor.load_bim_data(xlsx_path)

    # Extract quantities
    quantities = extractor.extract_quantities(df)

    # Generate reports
    output_dir = output_dir or Path(model_path).parent
    timestamp = datetime.now().strftime("%Y%m%d_%H%M%S")

    excel_path = Path(output_dir) / f"QTO_{timestamp}.xlsx"
    html_path = Path(output_dir) / f"QTO_{timestamp}.html"

    extractor.generate_qto_report(quantities, str(excel_path))
    extractor.generate_html_report(quantities, str(html_path))

    # Calculate specific quantities
    concrete = extractor.calculate_concrete_quantities(df)
    walls = extractor.calculate_wall_quantities(df)

    return {
        'excel_report': str(excel_path),
        'html_report': str(html_path),
        'summary': {
            'total_elements': len(df),
            'categories': df['Category'].nunique() if 'Category' in df.columns else 0,
            'types': df['Type Name'].nunique() if 'Type Name' in df.columns else 0
        },
        'concrete': concrete,
        'walls': walls
    }


if __name__ == "__main__":
    result = extract_qto_from_model(
        model_path=r"C:\Projects\Building.rvt",
        converter_path=r"C:\DDC\Converters",
        output_dir=r"C:\Projects\QTO"
    )

    print(f"Excel: {result['excel_report']}")
    print(f"HTML: {result['html_report']}")
    print(f"Concrete Volume: {result['concrete']['total_volume_m3']:.2f} m³")

n8n Workflow Integration

name: BIM QTO Extraction
trigger:
  type: webhook
  path: /qto-extract

steps:
  - convert_model:
      node: Execute Command
      command: |
        "C:\DDC\RvtExporter.exe" "{{$json.model_path}}" complete bbox schedule

  - load_excel:
      node: Spreadsheet File
      operation: read
      file: "={{$json.model_path.replace('.rvt', '.xlsx')}}"

  - group_quantities:
      node: Code
      code: |
        const grouped = {};
        items.forEach(item => {
          const type = item.json['Type Name'];
          if (!grouped[type]) {
            grouped[type] = {
              count: 0,
              area: 0,
              volume: 0
            };
          }
          grouped[type].count++;
          grouped[type].area += parseFloat(item.json['Area'] || 0);
          grouped[type].volume += parseFloat(item.json['Volume'] || 0);
        });
        return Object.entries(grouped).map(([type, data]) => ({
          type,
          ...data
        }));

  - generate_report:
      node: Code
      code: |
        // Generate HTML report
        return generateHTMLReport(items);

  - save_report:
      node: Write Binary File
      path: "={{$json.output_path}}"

Best Practices

  1. Model Quality: Ensure BIM model has proper levels and types assigned
  2. Units: Verify model units match expected output units
  3. Categories: Use consistent category naming for grouping
  4. Updates: Re-run QTO after design changes
  5. Validation: Cross-check totals against manual spot checks

Common Quantity Formulas

# Concrete formwork area (approximate)
formwork_area = concrete_volume * 6  # m² per m³ of concrete

# Rebar quantity (approximate)
rebar_weight = concrete_volume * 100  # kg per m³ (typical)

# Paint area from wall area
paint_area = wall_area * 2  # both sides

# Ceiling area from floor area
ceiling_area = floor_area * 0.95  # typical ratio

"Measure twice, cut once. Or better yet, measure automatically from the model."

FAQ

What does the ifc-qto-extraction skill do?

Extract quantities from IFC/Revit models for quantity takeoff. Uses DDC converters to get element counts, areas, volumes, lengths with grouping and reporting.

How do I install ifc-qto-extraction?

Run npx skills add https://github.com/datadrivenconstruction/ddc_skills_for_ai_agents_in_construction --skill ifc-qto-extraction in your project. The skills CLI detects the agents you use and copies the skill into the right folder. For Claude Code you can also place the skill folder at ~/.claude/skills/ifc-qto-extraction/ (personal) or .claude/skills/ifc-qto-extraction/ (project).

Which AI agents can use ifc-qto-extraction?

Any agent that supports the open Agent Skills format (a folder with a SKILL.md file), including Claude Code, Codex, Cursor, GitHub Copilot, Gemini CLI, Windsurf, Cline, OpenCode and more.

Is ifc-qto-extraction safe to install?

No partner security audit is available yet. Skills can run commands and scripts, so read the SKILL.md and any bundled files before installing.

Who maintains ifc-qto-extraction?

It is published by datadrivenconstruction in datadrivenconstruction/ddc_skills_for_ai_agents_in_construction. It has 154 recorded installs.

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