Truss Plugin/Extension


The “Layers” tab in the global settings will look something like this:


I’d suggest finding an alternate wording for your “Wall Gypsum Layer” as many designs use something other than Gypsum on the interior side! However, I’m don’t have a specific wording to suggest.


Agreed, the interior wall cladding could be wood paneling, lathe and plaster, or some other material but generally gypsum wall board is probably the most commonly used material, at least here in the United States and Canada. If other methods are used I would be interested to learn about those.


I was thinking specifically of wood paneling. But more generically - in search of the right word - I think we’re both looking for something that is the interior analogue of “sheathing”.

Actually, I intend to “sheath” the interior of my walls with tongue and groove wooden strips when I build my Tiny Home! It’s visually interesting, and strong enough to support anything I might decide to attach without having to mess with speciality anchors (at least I think so!). This is, of course, subject to insuring that the sheer strength of the wall doesn’t require a contribution from the interior “sheathing” to meet expected seismic loads.


don’t you ‘line’ interior walls…

plaster lining, timber lining, dry lining, etc…



Version 1.7.0 - 12.04.2016

  • Added a “Layers” tab within the global settings; roof, wall and floor components can be assigned to specific layers.
  • Enabled custom layers for the common fink truss.

Note that I have only enabled custom layers for one type of common truss (fink). To enable custom layers for all other truss types, rafter roofs and other misc. items will take a few hours of going through each module of the plugin and adding in the “layers” code or conditional statements. My arm/neck is not holding up very well but I thought it would be nice to at least get this out there for the most common truss type for testing purposes and feedback.


Went to all the trouble last night to roll the revision (1.7.0) and then somehow forgot to upload it to the server. The version you downloaded yesterday or last night is 1.6.9, please download and reinstall the plugin again to get the latest updates with the layer control. Real sorry about that.


Came across this thread recently. Not my engineering field, more into roads, drains, sewers and water mains.
But I’ve really enjoyed reading through the development of your plugin starting from scratch.
I feel like I have been inside you mind for the last year.
Good luck with future development. I hope it proves a commercial success.


I’m glad you have found the development of the plugin interesting enough to fully read through. Sometimes the journey is more interesting than the destination. The changelog is a much more condensed version of this journey:

However, it misses all of my tangents and conversations that I tend to take along the way. :slight_smile:

I’ve really only been working on the plugin for about a year now and there is a lot more to be done as well as two more plugins that I am hoping to get started on into the new year:

Medeek Structural Plugin

Medeek Wall Plugin

The structural plugin will deal less with the actual framing geometry and more specifically with the lateral and vertical engineering of the structure. It will be geared toward other structural engineers with the intent to automate residential structural engineering as much as possible.

Wood Shear Walls (segmented and perforated), Diaphragms (roof)
Beams, Headers, Joists, Rafters, Footings, Posts, I-Joists,
Rafters, Trusses

What will make this the killer app is that the 3D model will be able to automatically propagate the loads down through the structure while at the same time allowing the user to create the structure’s geometry in an intuitive and friendly 3D environment - SketchUp.

Of course the real power of such a plugin only become apparent when you create a model and then decide to build the house/structure in a different location with different site criteria. Rather than having to start from scratch you simply enter in the new wind speed, ground snow load, and seismic design criteria into the model and the plugin recalculates the entire structure and then alerts you on any members that are undersized or over stressed. This would be particularly beneficial to homebuilders who have a set number of model homes they use but build in various locations.


I’ve had a number of people asking about adding in the connector plates for the trusses. After giving this some thought it doesn’t seem like too much work to implement. I will try and work on this today and this evening.

I’ve already added in the option into the global settings:

Plate thickness can be set by the user (inches or mm). The default will be 0.0575 inches (1.46 mm) which is the total thickness of a typical Mitek M-16 connector plate:


Version 1.7.1 - 12.08.2016

  • Added truss connector plates within the global settings, plate thickness can be specified.
  • Added a “roof_mpc” layer for roof truss plates, connector plates can be assigned to a specific layer.
  • Enabled metal plate connectors for the common fink truss.

As with the recent layer upgrade I have only enabled connector plates for the common fink truss. This is to provide a test bed for the connectors then once the interface is fined tuned I will roll it out for all truss types.

At the moment the plate sizes are hard coded in. I am still trying to decide on the best method to use so that the connector plates can all be sized by the user. The objective is to make this a flexible as possible while at the same time not over complicating things.

View model here:


What I think I will do is add in one more option in the global settings which allows one to toggle the plate sizing to either auto or manual.

If auto is selected I will create a basic algorithm that looks at the truss span, truss pitch and depth of the TC, BC and webs and then sizes the plates accordingly. I already have such an algorithm built into my Truss Designer here:

If manual is selected I will have an additional html input screen appear that shows the location and size of each plate as well as the outline of the truss. The input will look similar to this:

As each plate is adjusted it will immediately change in size showing exactly the configuration of the truss with its connector plates. This involve quite a bit more coding however once I create one such html input, creating more will not be such a big deal. Each plate will be labeled P1, P2, P3 etc… Typically the location and rotation of each plate will have an optimal setting that does not need user input or adjustment.

The only question now is how to handle the gable end trusses. I think for now I will auto-size the plates on them using the same heel and peak plate sizes as the common trusses. For the the vertical studs I can use an algorithm that looks at stud length and then chooses either a 1.5x3 or 2x4 plate for connection to the top and bottom chords.

Adding connector plates adds a whole new level of complexity, but there have been enough requests for it that I think it is a valid endeavor. After all this is the “Truss Plugin” and I might as well get the trusses right.


Enabled connector plates for the common gable truss:

There gets to be quite a bit of geometry when you start modeling all of the plates, especially the gable trusses with all of their vertical studs.

View model here:


As an interesting side note, one can turn off the truss layer and then measure the volume of the steel plates which yields 113.85 in3. Multiply this by 0.284 for mild steel and you end up with a total weight of 32.3 lbs. That is actually quite a bit of steel plates in this rather small truss package. No wonder the truss plate manufacturers like Mitek make so much money on the sale of truss plates, the volume of steel is definitely there (194 plates).

The weight of the wood can just as easily be computed, making an assumption on the wood species (G, specific gravity of the wood), and moisture content (typically 19% at dry service conditions).

The appropriate equation to use for the density of wood can be found in the AWC NDS:

For DF No. 2 the density would be 34.2 lbs/ft[sup]3[/sup]

The volume of the wood is 22.06 ft[sup]3[/sup], multipled by 34.2 lbs/ft[sup]3[/sup] yields a total weight of the wood at 754.5 lbs. Steel plus Wood = 786.8 lbs.

It may be useful to provide weight information at both the truss component level and the entire truss assembly, wood, steel and total weight.


Enabled metal plate connectors for the 4/4 and 6/4 scissor trusses:

Each truss type and configuration needs its own special function to locate and auto-size each plate. The code required is not difficult since most of it can be recycled but it is still time consuming to generate for each and every truss type with all of the many possible configurations. I have not even considered raised heel trusses yet. At some locations (ie. heel plates on a scissor truss) the truss configuration may cause the plate to fall outside of the perimeter of the truss in this case some additional logic is required to check for these instances.

View model here:


When it comes to plates and connectors there is also the bolted plate connected trusses with larger timber members used for more architectural and ornamental work. I am wondering if there is any interest in having a separate module for those truss types?

Something along these lines:


The current TODO list:

  1. Hip Sets (Stepdown, California, Midwest, Northeast, Terminal) with and without drop-in purlin frames as applicable. Hip truss algorithm per June 15, 2016 post.
  2. Flat Trusses with html input.
  3. Barrel Vault, Clerestory, Studio Vault, and Double Inverted trusses.
  4. Html menus for each truss type.
  5. Update the manual and create more video tutorials.
  6. Extend connector plates and layers to each truss and roof type.
  7. Open Joist Floor Trusses.
  8. Polygon entry for floor trusses/joists versus currently available rectangular assemblies, also add in a function to cut a hole in the floor for a stair way or other opening. See Jul. 2, 2016 post.
  9. Dutch and Half Hip truss sets (See Jun. 14, 2016 post).
  10. Gable roof with solid sawn beam.
  11. Gable roof with “two” glulam or solid sawn beams. (cantilevered rafters).
  12. Html menu for each truss type for manual connector plate sizing.
  13. Add the roof to the gable dormer, see June 19, 2016 post.
  14. Hip and Shed Dormer.
  15. Gable, Hip and Dutch Gable Roof Minor.
  16. Engineering for Rafters, Joists and Sheathing.
  17. Bring the truss and beam engineering into the plugin versus an external link to my engineering site. This would require porting all of my Perl code into Ruby.
  18. Add a dual pitch gable rafter roof.
  19. Add raised heels to each truss type that currently does not have this feature.
  20. Finish adding bird blocking option.
  21. PDF or HTML output (printable) showing details of a truss assembly (ie. shop drawings and layout)
  22. Update order system allowing $20 yearly license renewal.
  23. Further investigate materials (colors) for specific layers.
  24. Allow “editing” of a truss, floor or roof assembly.
  25. Timber trusses (with bolted plates).
  26. Complex hip roofs, this is related to roof minors (item 15). Need to devise a straight skeleton algorithm.
  27. Integrate more tightly with other plugins as opportunity arises (ie. Estimator etc…)
  28. Gable end trusses for gambrel attic and attic trusses.
  29. Complete all configurations of each truss type and verify that each advanced option is correctly working (ie. polynesian truss needs more configurations).
  30. Add gable and full returns to the roof return option, currently only the hip return is available.
  31. Transition trusses.
  32. The Trim function seems to be working now I need to work on the Extend function.
  33. Steel and hybrid steel floor trusses.
  34. Explore adding in a stairway module and deck module, however these may become part of the upcoming Wall Plugin.
  35. In the advanced options for gambrel attic trusses create an option for a crow’s beak, see June 20, 2016 post.

The question is, other than item 1, what are the highest priority items on this list?

I’ve been basically sidelined since end of August so I am anxious to get this operation (neck) done with and over and really begin again in earnest to advance the development of the plugin.

My new job keeps me busy but not so busy that I can’t spend a few hours each night plugging away at this list and weekends are certainly my friend in that regard.

Please feel free to let me know what other items should be added to the list.


You’ve put an incredible amount of work into this plugin. My recommendation? STOP where you are (or close to where you are) in feature development/new truss types. Focus on making it easy to use with necessary help files. Then “officially” release it as “Version 1.0”. Then put it in an extension store where you can monetize it!

While I’m not - yet- at the point where I’ll use it. When I get there - especially knowing how much time it took you to date - I’d happily pay $10-$50 to use it.


I get the sense that the user interface needs some work. I will try to devote more of time focused on usability issues and implementing the html input menus (item 4).


Timber Truss Icon for the Graphical Truss Menu: