Skillion Roof Rafter Calc
Lean-To Framing Pitch & Angle
$1.99 · Designed for iPad. Not verified for macOS.
The ultimate skillion and lean-to roof framing calculator designed for carpenters, builders, roofers, and DIY enthusiasts. Get precise rafter measurements, birdsmouth cuts, batten layouts, and professional diagrams — all from your iPhone or iPad.
WHY THIS CALCULATOR?
Skillion and lean-to roofs are the most common roof style for sheds, carports, patios, pergolas, awnings, and home extensions. Yet most roofing apps focus on hip and gable roofs. This app is purpose-built for single-slope roof framing, giving you everything you need to frame with confidence on the job site.
COMPLETE RAFTER CALCULATIONS
• Rafter top length and total length
• Roof fall, pitch, and angle
• Birdsmouth plumb cut and seat cut dimensions
• Cut set-back measurements
• Perpendicular rafter depth
• HAP (Height Above Plate) calculation
• Automatic deep birdsmouth warnings
SMART RAFTER SPACING
• Equal spacing — distributes rafters evenly across the wall
• Exact spacing — maintains your specified spacing with adjusted end bays
• Running set-out dimensions for every rafter position
• Alternate spacing suggestions (next larger / next smaller)
• End rafter set-in support
BATTEN LAYOUT
• Automatic batten position calculations
• Equal or exact batten spacing options
• Running set-out for every batten
• Double-top-batten detection when spacing is exceeded
• Custom batten overhang support
PROFESSIONAL DIAGRAMS
• Plan view — top-down rafter layout with all running dimensions
• Rafter detail — side view showing birdsmouth cuts, angles, and key measurements
• Profile section — cross-section with wall heights, rafter angle, and overhangs
• All diagrams drawn accurately to scale
DUAL UNIT SYSTEMS
• Imperial — feet, inches, and fractions down to 1/32 of an inch
• Metric — millimeters for international standards
• Switch between systems instantly
EXPORT AND SHARE
• Export a complete PDF report with input data, calculated results, and all three diagrams — perfect for printing on the job site
• Export results as plain text for quick sharing
• Share via AirDrop, Messages, Mail, or any app on your device
BUILT FOR THE JOB SITE
• Works completely offline — no internet needed
• Clean, intuitive interface optimized for iPhone and iPad
• Fast, accurate calculations based on proven trigonometric formulas
• Upper wall and lower wall height calculations
• Overhang support for both upper and lower sides
• Wall thickness integration for precise framing dimensions
• Upper wall toggle for freestanding lean-to configurations
Whether you are a professional framer laying out rafters on a new build, a contractor estimating materials for a client, or a weekend DIYer building a backyard shed or carport, this calculator saves you time, reduces costly errors, and ensures every cut is accurate.
Stop doing complex roof math by hand. Download now and take the guesswork out of skillion roof framing.
Ratings & Reviews
- This app hasn’t received enough ratings or reviews to display an overview.
The developer, Vladislav Zhirnov, indicated that the app’s privacy practices may include handling of data as described below. For more information, see the developer’s privacy policy .
Data Not Collected
The developer does not collect any data from this app.
Accessibility
The developer has not yet indicated which accessibility features this app supports. Learn More
Information
- Seller
- Vladislav Zhirnov
- Size
- 4.8 MB
- Category
- Utilities
- Compatibility
Requires iOS 17.0 or later.
- iPhone
Requires iOS 17.0 or later. - iPad
Requires iPadOS 17.0 or later. - Mac
Requires macOS 14.0 or later and a Mac with Apple M1 chip or later. - Apple Vision
Requires visionOS 1.0 or later.
- iPhone
- Languages
English and 32 more
- English, Arabic, Croatian, Czech, Danish, Dutch, Finnish, French, German, Greek, Hebrew, Hindi, Hungarian, Indonesian, Italian, Japanese, Korean, Malay, Norwegian Bokmål, Polish, Portuguese, Romanian, Russian, Simplified Chinese, Slovak, Slovenian, Spanish, Swedish, Thai, Traditional Chinese, Turkish, Ukrainian, Vietnamese
- Age Rating
4+
- 4+
- Copyright
- © zhirnov.zsystems
