I've uploaded a test L-Shaped structure with a hip roof:

https://3dwarehouse.sketchup.com/model.html?id=u8d384878-941b-4df9-a8c9-8bba849765bb

I've created both hip roof primitives with the plugin, that was the easy part.

I then placed a valley rafter with its centerline (top) inline with both roof planes.  I think I've got it right.  What I am unsure of however, is the best way to terminate the framing at the intersection of the valley, lower ridge and flying hip.  Once I have a handle on how a carpenter would actually construct that junction I think I can proceed to start work on a secondary roof module for both hip and gable rafter roofs.

The secondary roof module will allow one to add secondary roof geometry to a main roof and have it automatically adjust the rafters accordingly.

Version 1.2.7 - 01.26.2016
- Added advanced roof options for hip rafter roof (sheathing, fascia).



https://3dwarehouse.sketchup.com/model.html?id=u3b08ddf6-b8be-405c-9ae6-912866e7a252

Some previous notes and images related to WGC trusses:

For the next week or so I'm going to spend some of my free time on wood gusset plate engineering.  I'm going to post engineering questions and some quasi-engineering questions regarding the connections.  Realize that some of these questions are me thinking out loud, contemplating how best to approach this type of truss design.

I'm looking at the nailing of the gussets right now and I'm considering the difference between nails in single shear or double shear. For larger fasteners (ie. 16d nails) it would seem optimal to clinch them on the reverse side and then calculate them in double shear. My question is at what length of fastener exceeding the total thickness can I functionally clinch the nails and consider them in double shear.

For argument sake lets assume a 1.5" truss ply thickness and 1/2" gusset plates each side giving a total thickness of 2.5". An 8D common nail is 2.5", however I would not consider it in double shear in this application. If I were to use a 10D thru 16D common nail in this situation I would have at least 1/2" of nail or more to clinch so in those cases I think I could safely assume clinching was possible and nails are loaded in double shear. Would less than 1/2" of nail protrusion be too small to clinch?

To open up the calculations to as many options as possible I'm considering 8d, 10d, 12d and 16d nails with all the three possible nail types: common, box, sinker.

I also considering 6d and 7d nails but I'm not sure if I will allows those yet.

The plywood or OSB thickness will be: 3/8, 7/16, 15/32, 19/32, 23/32.

Giving this even more thought it would seem that certain gusset thicknesses and nail combinations would not be optimal if the possibility for clinching and double shear is not possible. For instance if I have 23/32" gusset plates on both sides and 1.5" truss ply for a total thickness of 3". If I were to use a common 10D nail or 12D nail I probably could not clinch and therefore double shear is not possible, hence I would have to nail the truss from both front and back. Would this not tend to cause the main member to have more tendency to split since there are double the nails in it.  It would also require roughly double the nails.

I'm also going to assume that the osb/ plywood is Structural I, this would be my recommendation anyways in an effort to eliminate defects and require a stronger material for the gusset plates.  This affects both the shear values of the gusset plates and the lateral loading capacity of the nails.

Version 1.2.6 - 01.19.2016
- Added Solid Sawn Floor Joists (metric and imperial)
- Sill plate and Sheathing options (advanced) enabled for TJI and Solid Sawn floor joists.

Version 1.2.6 - 01.18.2016
- Sill plate option (advanced) enabled for top and bottom bearing floor trusses.




https://3dwarehouse.sketchup.com/model.html?id=u98d5f3e7-8cab-4acc-8160-7e20617e1814

Work on the manual is progressing however for those interested the red colored boards in the image are called  "ribbon boards".  This is fairly typical for floor trusses.  The notch purposely left in the truss to accommodate the ribbon board is called the ribbon cut or ribbon notch.  Continuous ribbons provide stability for installed trusses, and also provide a solid nailing surface for the edge nailing of floor sheathing. This eliminates the need for larger and more expensive “rimboard” solutions required by dimensional lumber and other engineered wood products.  2x4 lumber is common, but any dimension of 2x lumber can be used for the ribbon board.

Similar to the complex hip roofs I need to program the floor truss/TJI module so that it can automatically frame out any non-rectangular floor plan.

Variation in plate heights, pitches, overhangs and even mixing hip and gable (half hip, dutch gable) further complicate the matter.  To begin with I need a algorithm to generate the roof planes, then the framing just falls out from there.  To create the roof planes I need a fairly robust straight skeleton implementation.

Our natural world can always be broken down into simple patterns (mathematical relationships). When you identify those patterns and then act on them to your benefit that is when it becomes engineering.

Pondering complex hip roofs this afternoon and considering the graphic below:



A few rules seem to emerge:

1.) An outside corner will always create a hip that is 45 deg. from each leg of the corner.
2.) An inside corner will likewise always create a valley 135 deg. from each leg of the corner.
3.) Where two hips or flying hips meet a ridge will extend 135 deg. from each hip.
4.) When two valleys meet at 90 deg. they will terminate and a ridge will extend at 45 deg. from each valley.
5.) With a building with walls only running north-south or east-west all ridge lines will always be north-south or east-west.
6.) Likewise all hips, valleys and flying hips will be oriented northwest, northeast, southwest, or southeast.
7.) When a valley meets a ridge, (they will always meet at 45 deg) a flying hip is generated that is 90 deg. from the valley and 135 deg from the ridge. 
8.) When two valleys meet at 180 deg. from each other, the result will be either to flying hips perp. to the valleys or the degenerate case of 4 valleys and 4 ridges.
9.) When a valley and a hip meet each other at 180 deg. then two ridges that are 45 deg from the valley will be the result (typical L shaped roof).
10.) When 4 hips meet the result is a pyramid.

There may be a few other degenerate cases I'm missing but I think that covers it.

I have been giving some thought to dormers and how to specify them.  Below is a dormer design I framed in Solidworks a few years back for a garage design:








Of course the numerous ways in which one could frame a dormer is probably beyond the scope of this discussion but I would like to consider what geometry needs to be determined in order to orient and size the dormer.


After some thought I think the following points, planes and lengths would define the geometry of a typical dormer:


1.) Main Roof Plane
2.) Attic Floor Plane
3.) Offset from exterior wall below (how far the dormer is out of plane from the ext. wall below).
4.) Pitch of Dormer roof
5.) Dormer width
6.) Dormer height (distance from attic floor plane to top plate of dormer wall)
7.) Window width, height, and header depth
8.) Dormer wall thickness (2x4 or 2x6)
9.) Dormer rafter depth
10.) Position of Dormer along length of building


Items 2,3 and 10 can be combined into a single point selection.

As you can see there is still a tremendous amount of work that can be done here.  To that end I've started a KickStarter project which if successful would allow me to devote at least 4-5 months of my undivided attention on the programming of this plugin:


https://www.kickstarter.com/projects/128644708/medeek-truss-plugin

Testing the limits of the Medeek Truss Plugin with complex hip roofs. Note that the roof primitives have not been trimmed back. This is primarily a study to determine what additional programming would be required to generate this type of roof automatically:





This for me would be the holy grail of hip roof framing...

Hip Roof Framing:



SketchUp model used in the video can be found here:

https://3dwarehouse.sketchup.com/model.html?id=u53e50317-d46f-40dd-a95f-c50b1d51302d

Valley Truss Set:

Engineering Video:



The SketchUp model used in the video can be found here:

https://3dwarehouse.sketchup.com/model.html?id=u6c602b47-40bb-4349-9e0e-0917746ab90a