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 DIY Chatroom Home Improvement Forum Building Garage with Engineered Trusses
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06-15-2013, 05:16 PM   #16
Old School

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Don't mean to nit-pick, but I honestly hope you are more careful with your calculations than you were with the proof-reading on that website.

I know you must have had the best of intentions, but a 5th grade teacher would tear you up on the mistakes and typos in that presentation.

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Willie T

 06-28-2013, 05:31 PM #17 Architect / Engineer     Join Date: Jan 2013 Location: Copalis Beach, WA Posts: 18 Rewards Points: 28 With a little help from a text called "Design of Wood Structures" by Donald E. Breyer and a recently purchased copy of the NDS 2012, the equations in TPI 1-2007 finally made a lot more sense (I was having some confusion with the bending effective length vs. the buckling effective lengths, combined bending and axial compression). I will say this has been quite an education with regards to structural design of wood structures. Last night I finally completed the full lumber analysis for the fink truss. Top and Bottom chords as well as all the webs. Now its time to start working on the heel joint check and all of the connector plates. Wind loads might be next but I need to research this quite a bit more. After doing some reading on trusses it seems that the simplified method of calculating moments should be fine for statically determinate common trusses such as a fink, howe, king or double fink truss. Its when you start trying to analyze the statically indeterminate variety (ie. attic trusses) then the simplified method really comes up short. For that I will need RISA integration with the app.
 06-28-2013, 06:03 PM #18 Remodel and New Build GC     Join Date: Sep 2010 Location: Colorado @ 7651' Posts: 4,590 Rewards Points: 5,450 Medeek...... Wish I could contribute... but basically it's over my head.... but darn interesting from a conceptual standpoint... to see just some of the calcs that go into a truss design. THANKS Peter __________________ Never stop learning (xcep fer speling en typeing)

06-28-2013, 06:36 PM   #19
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## Lots of Calculations

Actually it was a bit over my head initially when I first cracked open my copy of the TPI standard. I've never done a whole lot of structural engineering of wood so I had to become familiar with the equations and the process. However, once you step through it, member by member it does actually all make sense. My observations after digesting the bulk of the NDS manual is that wood engineering is all about "factors", loads and effective lengths. Then it is just a matter of plugging these factors and a few variables into the corrects equations for the given application and you either have a go or a no-go, its actually pretty simple.

With trusses, as is the same with beams and columns you make some assumptions then apply a number of checks in order to specify the lumber type and size. You start with a given lumber type/grade and then work your way up until it meets or exceeds all of the checks.

 The Following User Says Thank You to medeek For This Useful Post: MTN REMODEL LLC (06-28-2013)
10-02-2015, 10:09 PM   #20
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I haven't posted about the truss designer for a while, apologies for that.

Still trying to improve it as time allows. The list of upgrades and improvements was getting rather lengthy so I've created a changelog page here:

http://design.medeek.com/calculator/changelog.html

Unfortunately, I had to put a daily limit on its usage because the server was getting hammered but it is still free to use.

The biggest improvement is the ability to specify the lumber grade, size and species as well as utilize point loads. This should make this tool far more useful for those wanting to check their roof for solar panel installations.

I'm still thinking about generating a 3d model for those wanting to import the truss directly into programs like Sketchup or REVIT

I appreciate all of the support I've received over the last couple of years on this project. Suggestions/feedback is always awesome.

 10-03-2015, 05:17 PM #21 Architect / Engineer     Join Date: Jan 2013 Location: Copalis Beach, WA Posts: 18 Rewards Points: 28 Added SketchUp 3D (.rb) file output for the truss geometry. This file, when copied into the SketchUp plugins folder, will create a menu item within SketchUp allowing for unlimited creation of the given truss geometry within SketchUp. I think this feature will be particularly interesting to those DIYers who wants to draw up their own model and plans using SketchUp.
 10-03-2015, 05:18 PM #22 Architect / Engineer     Join Date: Jan 2013 Location: Copalis Beach, WA Posts: 18 Rewards Points: 28 I've updated the code so that the plugin now allows for user input in order to specify number of trusses and spacing of the trusses. For example 4 trusses @ 24" o/c would give you: The actual truss geometry cannot be altered within SketchUp it is hard coded into the plugin when it is created by the calculator. For different truss sizes and shapes it is simply a matter of creating and storing separate .rb files for them. Dropping these files into the SketchUp folder sets up the menu item. This method seems to be the easiest for interacting with the SketchUp API.
10-17-2015, 03:19 PM   #23
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## Attic Trusses created in SketchUp Plugin

This is the same truss I used in my 28'x48' garage:

Now I need to work on the energy heel option for this truss as well as some additional logic for attic trusses in the following span ranges 16-24 feet and 30-36 feet.

10-20-2015, 09:04 PM   #24
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## Medeek Truss Plugin - 1.0.4

Howe truss type is now active.

The latest plugin version is 1.0.4. I would highly recommend downloading the latest version since I have also spent some time this morning cleaning up my code and removing global methods and variables so that I don't clash with other extensions or modules.

10-24-2015, 05:33 PM   #25
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## Scissor Trusses

Version 1.0.5 - 10.24.2015
Added Scissor truss type, configurations: (2/2), (4/4).
Metric input enabled for scissor truss types.

In certain instances the scarf length of the bottom chord becomes less than the bearing length, the logic checks for these cases and inserts either a 3.5 or 5.5 heel wedge as required.

 10-24-2015, 05:54 PM #26 Member   Join Date: Nov 2008 Location: Southeast MA Posts: 1,803 Rewards Points: 114 Lot of work...but not really appropriate for this board. Read the guidelines. Ron
 The Following User Says Thank You to ront02769 For This Useful Post: Festerized (10-24-2015)
 10-29-2015, 09:02 AM #27 Architect / Engineer     Join Date: Jan 2013 Location: Copalis Beach, WA Posts: 18 Rewards Points: 28 I've got gable end trusses working for king post 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.
 11-25-2015, 09:13 PM #28 Architect / Engineer     Join Date: Jan 2013 Location: Copalis Beach, WA Posts: 18 Rewards Points: 28 Version 1.1.5 - 11.25.2015 - Added Double Fink common truss type. - Structural outlookers (vert. & horz.) enabled under advanced roof options for Common (Double Fink) truss type. For the DIYer a garage roof can be modeled in SketchUp within a matter or seconds. I also highly recommend the house builder plugin which is great for wall framing. Last edited by medeek; 11-25-2015 at 09:16 PM.
 11-26-2015, 11:24 PM #29 Member   Join Date: Nov 2008 Location: Southeast MA Posts: 1,803 Rewards Points: 114 Any chance you read the guidelines about not pushing your own crap on the. Board?.
03-12-2016, 07:46 PM   #30
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## Re: Building Garage with Engineered Trusses

Another study of hip roof framing where unequal pitches meet at the hip. The birdsmouth cut is 3.5" for all jack and common rafters. The hip rafter is dropped and off center so that it lines up with the roof planes. The hip roof combines a 12:12 pitch with a 6:12 pitch.

View model here:

https://3dwarehouse.sketchup.com/mod...b-56bc73878207

Where the pitches are unequal like this it might make more sense to use a backed hip rafter rather than a dropped hip rafter. Does anyone have any suggestions or experience dealing with hip rafters that join unequal pitches?

Last edited by medeek; 03-12-2016 at 07:48 PM.

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