SBE Builders

Strong Built Establishments Builders

SBE Builders is a commercial and residential framing contractor located in Discovery Bay California. Dedicated to the art of Carpentery & Roof Framing. We are the professionals for the future of the craft of carpentry.

Bowed Bay Window Rafter Calculator with Unequal Overhang v1.0
Bowed Baywindow Rafter Calculator

    Span in inches
    Number of Bay Windows > 1
    Projection Of Bay Windows
    or enter Bay Window Angle
    Rafter Overhang
    Rafter O.C. Spacing At Plate Line
 P   Major Rafter Pitch
    or enter Major Angle

show results in feet & inches


results are show below in the IFrame window

Warning this bow window roof framing should only be attempted by master roof cutters and stackers.
Check the printed results with the auto generated DXF file each time this script is run.

At the bottom of this page there are links to diagrams, sketchs and bowed window roof framing development of this script.

All online tools use javascript to calculate the dimensions. Use at your own risk. If the answers look wrong then verify the answers with a calculator or with Joe Bartok.


Bow Window with Unequal Overhang Example


Bowed Baywindow Diagram Joe Bartok's Bowed Baywindow Sketch with 5 bays
Bowed Baywindow Diagram Joe Bartok's Bowed Baywindow Sketch with 7 bays
Bowed Baywindow Projection Solver Joe Bartok's Bowed Baywindow Projection Solving Calculator
Bowed Baywindow Trial Angle Solver Joe Bartok's Bowed Baywindow Trial Angle Solving Calculator


Bowed Baywindow Roof Framing Development at the Journal of Light Construction JLC-Online Forum


Bowed Baywindow Sketch Bowed Baywindow Sketch with 5 bays
King Common Run in Bowed Baywindow Sketch King common rafter run with medians and altitudes scalene triagnles
Odd Numbers of Bays Dimensioning Bowed baywindow dimension example of how the projection is calculated with odd number of bays
Even Numbers of Bays Dimensioning Bowed baywindow dimension example of how the projection is calculated with even number of bays
Bow Window 2 Sided Bowed baywindow dimension example with 2 baywindows
Bow Window Perl and Javascript comparison test script Bowed baywindow best fit results comparison

Code used to calculate projection offset for Bowed Baywindow For Odd Number Of Bays

central_angle = theta * bays
radius = span /(2 * sin(central_angle / 2))
d = radius * cos(theta / 2)
side_angle = (PIE - central_angle) /2
radius_layout_offset  = (span/2) * tan(side_angle)
offset = d - radius_layout_offset 

Code used to calculate projection offset for Bowed Baywindow For Even Number Of Bays
central_angle = theta * bays
radius = span /(2 * sin(central_angle / 2))
d = radius * cos(theta / 2)
side_angle = (PIE - central_angle) /2
radius_layout_offset  = (span/2) * tan(side_angle)
offset = radius - radius_layout_offset 

Bow window: A composite of two or more window units in a radial or bow formation also known as a walk-out bay window installation where the wall follows the bowed out angle of each window. Or a rounded Bay Window which projects in a semi-circle from the surface of an exterior wall.

The DXF file generated each time the script in run will have the arc construction lines drawn as well as the plan view of the hip rafters.


unequal-bowed-baywindow.dxf -- auto generated DXF CAD file of bowed baywindow drawing each time script is run

 

King common rafter runs clarification.

Each bay window roof plan triangle, formed by the fascia line and 2 bay hips, is a scalene triangle. Which means all 3 sides of the triangle are unequal in length. Because of the unequal sides of the triangle the normal king common rafter run is often located outside of the bay hips when drawn at a 90° to the plate line.


OPTION # 1:
King hip rafter runs for each bay are located in the center of the bays hip rafters. This is the same as the median of a triangle.\nThe king hip rafter runs are not located in the center of the baywindow wall framing. The king hip rafters are not at 90° degrees to the plate line or fascia line. By locating the king hip rafters in the center of the bays hip rafters, each king hip rafter will be centered in the fascia line of each bay.

OPTION # 2:

Or if you prefer to use the altitude of each bay for common rafter runs. You can use the information printed out at the bottom of the results to calculate the common rafter lengths with the altitudes for the common rafter runs.

Bowed Baywindow King Common Run Rafter Layout

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SBE Builders
SBE Builders
5305 Laguna Ct.
Discovery Bay, California 94505
(925) 634-6022 • Fax: (925) 634-6022
Commercial & Residential Framing Contractor
American Carpenter and Builder
California Licensed General Building Contractor
CA LIC.#  546126


Roof Framing Geometry

  • Roof framing geometry is empirical-type knowledge.
  • Information gained by means of observation, experience, or experiment.
  • From ground Line 0: Z1, Z2, Z3 etc...
  • To Roof Axis 0: A1, A2, A3 etc...
  • To the bring back line 0 for scribing: B1, B2, B3 etc...

Roof Framing Geometry Blog

Rafter Tools for Android
With Quad Tetrahedra Analytic Algorithm Technology.
Helping apprentice carpenters on their journey to becoming master carpenters with Certification in roof framing.

Rafter Tools+ for iPhone

Rafter Tools+ is a rafter calculator for complex roof framing angles that other roof framing calculators don't offer.

RafterTools+

Stair Tangent for iPhone

This iPhone app is for rough frame carpenters that don't build stairs everyday, but could use an stair app calculator to check their stair building calculations. Build a set of stairs that you are gonna be proud of. With Stair Tangent you can elimenate cumulative math errors when building - constructing stairs.

Stair Tangent
stairtangent.com

Crown Molding Tools
crownmoldingtools.com

Crown Molding Tools  

Carpenters Of Steel

Canadian & American Geometric Roof Framing Development
using a Steel Framing Square

Geometric Roof Framing Development for Irregular Hip Roof Calculations
using a Steel Framing Square

Geometric Development of Tetrahedron
using a Steel Framing Square

Hip Rafter Backing Bevel Angles from 1565 to 2013

Applied Geometry and Euclidean GeometryA lesson in Applied Geometry and Euclidean Geometry

This Is Carpentry

We're a member of the Timber Framers Guild

Timber Framers Guild

American College of the Building Arts, carpentry and timber framing programs.

American College of the Building Arts

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