Truss Plugin/Extension


Version 1.4.0 - 03.15.2016

  • Added LP Solidstart® I-joists: 450, 530, 18, 36, 56.
  • Rim joist option enabled for LPI floor joists.


Version 1.4.1 - 03.16.2016

  • Added Soffit Cut within Advanced Options for Gable Roof and Gable Roof w/ GLB.


Coming up on the 6 month anniversary of the plugin (April 7). I’m pretty excited with the amount of work I’ve been able to do on it. I would really like to get to some more big items on the list like secondary roofs and dormers but that will take a few days of uninterrupted programming which is really hard to come by at the moment. Lately, I have been addressing mostly minor items that I can knock out in a a couple of hours. I usually don’t start into a big project unless I think I can complete it in one go since it is really hard to partially complete it and then try to jump back into it at a later date. The higher the complexity the more this holds true.


I’ve been considering transition trusses and what it might take to add them into the plugin. Below is a quick study of this type of roof. I am curious to know if a common trusses is butted up next to a transition truss for sheathing purposes. Also notice the scissor transition, this situation is a little complicated, not exactly sure how to deal with it.

View model here:

For clarity I have removed all of the common trusses in the image below:

I think it would look something like this:

however I think the framing at the lower peak would be more correct if the top chord members abut like this:


This is a re-visit of the unequal pitch hip roof a few days back. Larry Belk, an experienced architect whose advice I highly regard, has suggested that an alternative way to handle this type of roof is to raise the top plate and thereby allow the overhang to remain constant around the roof:

View model here:

Compare with hip roof 7:

and model:

A few things pop out at me here.
First the raised top plate method allows the constant overhang with the continuous fascia, overall this is more aesthetically pleasing.
Second the hip rafter is no longer at the corner but is jogged in some amount onto the higher wall.
Third, the higher wall actually is protruding through the sheathing of the lower pitched roof in the model. Obviously the higher wall needs to be trimmed back some to deal with this.

For the plugin I think I will probably go with option 1 above initially but at some point it would be good to have a checkbox that allows one to choose either of these two options, the code is going to get ugly.


Version 1.4.2 - 03.19.2016

  • Added energy/raised heels for attic trusses (1 variant: vertical w/ strut).
  • Addressed some minor usability issues with the attic truss menu and options.

View model here:

I’ve had quite a few people asking for this update so stayed up most of the night and knocked it out. Note, that the raised heel option is currently limited to attic trusses with a span of 24 ft. or greater. The reason for this is the way my logic currently works with spliced top chords. If this becomes an issue I will spend some more time on it to encompass attic trusses with a lesser span. I still do not have the gable truss, metric input or structural outlookers for this truss type, yet more items for the “todo” list.


Thinking about dormers today and attic trusses:

View model here:

2-ply girder trusses on each side of the dormer with ladder framing between. I haven’t bothered to show all of the main floor framing geometry (doors, windows, stairs etc…) My question is what would be the best route for the infill framing above the dormers.

1.) Ladder frame perpendicular to trusses.
2.) Install a ridgeboard hangered between the girder trusses and a lower header and install rafters parallel to the trusses?


A basic algorithm to convert a common gable truss into a transition truss should not be to much problem. However, to make it handle all cases would become difficult if you include raised energy heels, drop top chords and scissor trusses in the mix. Consider the two examples below:


Version 1.4.3 - 03.20.2016

  • Added Scissor truss type, configuration: (6/6).
  • Added energy/raised heels for scissor trusses (2 variants: wedge and vertical w/ strut).
  • Addressed some minor usability issues with the scissor truss menu and options.

View model here:


Have you developed a double slope (plantation style) truss or rafter system? I couldn’t find any references to a roof of this type


I would call that a polynesian roof:

Up until now I have not given it much consideration since no one has specifically requested it. I have spent some time study the geometry of this truss type and what type of logic would be required to generate the double slope.

Do you have any shop drawings that you could send me that would further me along in my study of this roof type? Do you prefer a truss or rafter solution?


Polynesian 4/4 truss is working:

However, I haven’t released this latest update yet, I still need to enable gable end trusses and advanced options for this truss type before it is ready for prime time.

The inputs are similar to all other truss types except you have two top chord pitches and a pitch break length measured from the left butt cut of the truss.


So… I am assuming that you have totally given up on sleeping, at this point? You are making huge advancements so quick! Great job!


Yeah, pulling back to back all nighters is never a good idea, I’m paying for it now… I had already been thinking about the polynesian truss type so I wanted to get some of my ideas into code before misplaced them. The only problem is once I start programming I quickly loose track of the time.


Version 1.4.4 - 03.21.2016

  • Added Polynesian truss type, configurations: (4/4).
  • Metric input enabled for polynesian truss type.
  • Added gable end trusses for polynesian truss type.

I’m not sure where this type of truss is commonly used but whenever I see one I think of a bus stop or train station:

View model here:

Advanced options are not yet enabled for this truss type yet, so sheathing, fascia, rake will have to come later.


After adding Bowstring and Bow Barrel trusses the only common other round truss type is the Barrel Vault. The problem with this type of truss is the webs get messy or at least hard to predicate because of the interplay between the vault and the pitched roof above it. In an effort to better understand this type of roof/ceiling configuration I’ve created the matrix below:

High Res. PDF copy here:

I am trying to predict the max. height of the vault given a specific roof pitch and and vault width to span ratio. Perhaps I am recreating the wheel and some architect or designer has devised a method to create the perfect barrel vault given a roof pitch and other criteria.

I would be interested in what other opinions are on this matter.


Using a typical Barrel Vault 8/7+4 or 8/7+2 configuration I come up with the following triangulations. I’m sure there are other methods of configuring these webs but for the purposes of the plugin I think these solutions will suffice for now:

High Resolution PDF copy here:

Based on this matrix I’ve been able to come up with a simple algorithm for the triangulation of this truss type. I’ll admit the barrel vault truss is one handsome devil.


A 9:12 barrel vault truss with a 16’ wide barrel:

The design of this type of truss is controlled by the following parameters:

1.) Out-to-out span
2.) Top chord pitch
3.) Barrel vault width
4.) Barrel vault radius

Assuming a typical web configuration as shown above the truss design is really only dependent on these four inputs. Minor details with regards to member depths, overhangs and ply thickness also factor in as well but don’t really change much.

I can also see the possibility of running a raised heel variant but I don’t know how common that would be.

Has anyone ever seen a gable end version of this truss type? My thinking is that it might make more sense to just use a common gable truss otherwise you would be looking at some very complicated wall framing below the truss.


It’s a common roof type here in Hawaii. They are used with gable ends as you’ve shown, but are also used in a hip configuration with the steeper top chord forming a dutch hip.

I’m interested in both the truss configuration as well as a conventional cut roof (rafters). Using rafters allows for a more dramatic vaulted ceiling effect. Trusses, however are more economical.

Thanks for incorporating this roof type. Looking forward to the advanced options, maybe with the hip option?, when you get the time.

Thanks, Ron


I would be interested in looking at any drawings or photos you have of the hip configuration of the polynesian truss. I will need something like this to assist me in adding this additional feature into the advanced options.

I would also be interested in adding a conventional rafter roof for this configuration however again I need some pictures of additional information so that I get it right.