Given the slopes of the dual pitch truss and the span calculate the distance between the left bearing and the peak:



However, you might notice that we are assuming the buttcut and top chord depth is equivalent for both sides.  If the slopes are different then this will mean that the heel heights will be different.  Should the heel heights be the same?

Version 1.1.2 - 11.16.2015
Metric input enabled for monopitch truss types.

I've also added advanced options for monopitch trusses (sheathing, rake and fascia).

Version 1.1.1 - 11.14.2015
- Gable end trusses enabled for all monopitch truss types.
- Added energy/raised heels for monopitch trusses (3 variants: wedge, slider and vertical w/ strut).


Currently there are only two versions of the monopitch truss available (2/2 and 3/3). 

The truss set below shows a monopitch truss set with gable ends and a 36" raised heel.

An interesting implementation of a straight line skeleton algorithm is at this link:

Actually let me rephrase that, any roof can get very complicated with intersecting roof lines whether it is framed out with trusses or more traditional rafters and beams.

If I incorporate traditional framing I would like for the user to be able to indicate the perimeter of the ext. walls and for the logic to be smart enough to handle any possible configuration.  Consider the custom home with guest house below:



Just to determine the proper placement of the ridge and valley lines requires some serious algorithms.  The technique I used to do it manually simply involves drawing isolines moving a fixed increment in from the ext. wall line.  These are really no different than contour lines on a topographic map.  The vertexes created by the intersection of these lines indicate the location of hip rafter, flying hip rafters and valley rafters.  When the isolines merge into one line then you have a ridge board.

This process is known as the straight line skeleton:

https://en.wikipedia.org/wiki/Straight_skeleton

I haven't even looked at traditional roof framing, its been all trusses and some floor joists until now.


Hip roof framing is very complicated especially with intersecting roof lines:





and

On a slightly different note I'm thinking about creating a plugin for wall framing and other misc. framing related items for residential construction:

- Walls
- Floors
- Stairs
- Dormers
- Foundations
- Posts and Beams
- Square and Round Footings

Any great ideas on names.  Its going to be something like Medeek Framer or Medeek Construction but I just don't want to make it too narrow in scope since I will probably wrap a number of things into it.

I like the housebuilder extension but I think a lot more can be done based on this initial concept.

Items I would like to see are more flexibility in defining openings, double trimmers, double king studs, double window sill plates. 

I would also like to have the ability to create portal frames per the IRC standard.  As well as classify certain wall segments as shearwalls and automatically insert the holdown components (Simpson HDU series) into the wall.

For structural engineers I've got some ideas for a plugin called Medeek Structure which will do lateral load analysis for wind and seismic similar to the Woodworks Shearwall software that I currently use on my local engineering projects.

Version 1.1.0 - 11.10.2015
Gable end trusses enabled for the Fink truss type and all raised heel variants.

I may need to adjust the vertical studs slightly for the raised heel with slider.  I haven't yet determined the best way to frame that situation out.

I need to be able to select a face from a truss (truss top chord) even when the entire truss set is nested within a group -> component -> group. I'm going to assume this is possible, even though I don't know how to do this yet. If I can do this I can see a path to creating the valley set code which will allow one to insert a valley set behind a given truss set and have it frame over the main roof, conforming to the main pitch of the roof. At this point I'm only going to make it work if the two ridge lines are perpendicular. If they are different than 90 degrees the calculations are going to be a nightmare, I'll put that one on hold for a later time when I feel particularly ambitious.

I should be working on my regular work but SketchUp has an addictive hold on me at the moment.  Trying to do a bit more complex roof line below.  Immediately some things that pop out are the inherent complexities that occur when roof lines meet.  The question is how to setup the plugin to automatically handle these situations, this will not be easy.  I was able to easily trim and delete unnecessary rake and fascia boards as required.  The trusses themselves need to be more dynamic so that one can adjust the overhang to zero as required.  It is easy to select a number of component instances and make them unique and then adjust as required.  In the second image I've copied an instance of the queen post truss to create a girder analog. 


The other thing that needs some attention is the ability to easily create a valley set that frames over the larger roof line.  I've got some ideas on this one, its going to take some interesting math but its not impossible.

One can go so far as to put all of the H1 ties in.  I could waste an entire day messing around in this software, way too much fun.

Just playing around with SketchUp a bit today and trying out the new sheathing, rakeboard and fascia capabilities in the plugin.


The roof of this simple structure took all of 10 seconds to create, the rest about 20 minutes.  I didn't realize Simpson Strongtie hardware is available in the 3D warehouse, good to know.




I'm not going to say anything about lateral bracing of this structure, just modeling for fun.

Version 1.1.0 - 11.08.2015
Added advanced roof options for Common, Scissor and Attic truss types.
Sheathing option enabled under advanced roof options.
Rake Board option enabled under advanced roof options.
Fascia (Flush, Dropped, Beveled) option enabled under advanced roof options.




2x6 fascia and rake boards with gable end trusses.  I would show the sheathing but it covers up the trusses and then there is really nothing to look at.

Angled bird blocks seem to be the norm around here (Western Washington) however vertical blocking inline with the ext. wall framing seems to be the more acceptable and approved method.  A max. 2" space is usually allowed for venting purposes however as a structural engineer I like to see full height blocking to the roof sheathing/diaphragm especially over shearwalls or braced wall lines.

I can probably provide two to three option for blocking once I have arrived at a consensus on what is the most popular method(s) for blocking at the truss heel.  Please feel free to chime in with suggestions or preferences in this regard.