In its current form the truss plugin is only capable of generating geometry. It does not attempt to engineer or size the members, that information is input by the user. For engineering of a common fink truss you can try my Truss Designer here (note that I have not even progressed to any other truss type yet due to the complexity and sheer volume of checks required for a typical truss):
So unless you have a rough idea of what your loads are and what the member sizes will probably be or you already have this information from shop drawings of a truss manufacturer then your sizing of the top and bottom chords is a guess at best and may change when the quote comes back from the truss manufacturer.
I think what you are requesting is the ability to make the member sizes parametric so that they can be updated easily within the component at a later time when more information is present about the truss engineering. I agree that this would make the geometry and the plugin that much more useful. However, I did not know that SketchUp has any parametric abilities. I will have to look into this further and see what I can do.
I’m from the United States. I am intimately familiar with the ANSI/TPI 1-2007 and ANSI/TPI1-2014 which govern the engineering of MPC wood trusses. Unfortunately, this document does not go into a lot of the industry practices for the design of these trusses. For that I have to examine shop drawings from Alpine, Mitek and others. However, after a quick examination of these drawings the methods, algorithms and techniques used to triangulate most any truss type pops out rather quickly.
My intent with this plugin in its current form is to offer a quick method of generating geometry that conforms to current industry design methods. Given my limited time and resources it is not possible to make this plugin capable of generating every possible geometry (ie. stub trusses). However, for many typical truss profiles it should be quicker than manually drawing them.
Version 1.0.6 - 10.25.2015
Added floor truss type, Modified Warren - System 42.
Metric input enabled for floor truss types.
Top and bottom bearing option enabled for left and/or right end of floor trusses.
Ribbon cut option (top) enabled for left and/or right end of floor trusses.
I haven’t made this latest update live just yet as I need to update all of the other truss types to make sure it does not break anything.
The other thing I am changing is the second user prompt box that allows one to enter in the number of trusses. I have now switched to a building length and the logic spaces the trusses based on the this length and the truss on center spacing. Gable end trusses can be switch on or off. Spacing of the gable studs is another user input.
I have a question or request for our Mac/Apple users. Has anyone tried using the plugin on a Mac. I don’t have access to a Mac so I have no way of testing the plugin to see if it actually might work on this platform. If someone would be willing to test it out for me I have no problem in setting them up a permanent license and sending them the full version of the plugin, this would help me out a lot.
I’ve had to take a bit of a break from my coding, too much local work to process and never enough time in the day to get everything done.
As Juju (on Sketchucation forum) suggests, I am going to try and figure out a better positioning mechanism before I start adding more truss types or additional features. This is the biggest thing holding the plugin back right now. If I can figure out a good solution for this I think the ability to create an entire truss package with a couple user prompts and three mouse clicks is definitely taking things to a new level.
If you could track three clicks, you could establish the placement point (Click 1), the length of the truss, and orientation (distance between Click 1 and Click 2) and the length of the run (distance from Click 2 to Click 3).
That is what I intend to do. I just need to find some sample code that does this sort of user input or pour through the documentation. It probably is not that hard to do I just need to sit down and figure it out and then implement it.
Version 1.0.7 took a while to figure out The big improvement is the ability to click with the mouse at three corners and place the truss set without any additional rotating or translating.
In literally seconds I can now put a floor and a roof on 4 walls using the truss plugin and the Homebuilder plugin:
Of course the gable walls are not quite right but you get the idea. I may have slightly misunderestimated (a word created by GW Bush) SketchUp and what one can do with it.
The biggest hurdle was to learn how to create and properly set up a “tool” within the API. Adding different truss types is much more fun than working through that mess.
I’m also thinking it might be useful to have an option to put sheathing on the roof and/or floor?
I’m also looking for a good plugin that does stemwall and slab on grade foundations, if anyone has recommendations please advise.
I may actually use my own plugin for my own practice in order to quickly mock up certain structures and provide visuals. With the right tools I think SketchUp can be a very effective and quick turnaround platform
Only a rectangular configuration is available currently. If I can figure out how to code a polygon version of this that would be much more impressive (ie. pick the points that define the perimeter of the foundation and the plugin generates the complete floor layout).
This is straying a bit from trusses but I figured if I’m going to include floor trusses I might as well make floor joists available as well, just a small bit of code to get there.
If I develop the polygon idea further and make the floor framing more complex then I will probably need to do that but for now I’m going to keep the focus on trusses.
I’m considering adding the following advanced options to roof trusses:
1.) Sheathing
2.) Fascia
3.) Rake Board (Gable Overhang)
4.) Outlookers (Structural vs. Non- Structural, Horizontal vs. Vertical)
5.) Vent Blocks
This would then provide a fairly complete roof framing solution.
As I’ve been contemplating adding gambrel attic trusses to the truss plugin I’ve had to give some thought to what constitutes a good gambrel design. I’ve looked into this before but my recent conclusion is that no matter the lower and upper pitch of the roof a good looking design seems to be always achievable if the lower and upper legs of the roof are more or less equal in the length. To that end I’ve devised a simple spreadsheet calculator that will quickly throw out the numbers and display a graphic of the gambrel profile based on this assumption:
I’m not saying this is a hard and fast rule but it seems to give decent results. Minor variations (ie. L1 not equal to L2) are generally okay but if one leg is significantly longer than the other the gambrel profile becomes distorted.
The math to come up with this equality and generate the coordinates of the overall roof height and the pitch break is rather interesting and for those mathematically inclined is given below. Note that the equation ends up being a quadratic equation with the positive root extraneous:
There are other calculators and literature out there that talk about circumscribing the roof within a half circle but this only really works if the two pitches are more or less equal in my opinion.
I’m working on the advanced options for roof trusses and I’m looking at the fascia board. I’ve come up with three different configurations for the fascia that I’ve seen in practice and in the architectural books that I have.
Which method of the three below do you prefer? or is there another configuration that I have missed?
Sometimes the roof rafters have a kicker that makes a shallower angle for the first few rows of tiles/slates and there is no fascia (gutter brackets are fixed to top of wall-head).
Sometimes the fascia actually extends above the rafter end and a gutter flashing is dressed under the first row of tiles/slates.
There are also loads of different ways to do soffits and boot-ends. A lot will depend on how the rafter is supported; our most common construction method is to form a birds-mouth in the leg.
On another board I’ve been posting similar updates to the plugin as I’ve made progress on its development. However, after some complaints from admins I’m thinking perhaps it is not appropriate that I discuss the day-to-day development of this plugin in the forums. I’m not entirely sure of the protocol on this since this is new territory for me. I will probably continue to field questions on this board related to the posts made thus far but if you would like to closely follow the development of this plugin please email or PM me.
