Existing 2x4 garage truss storage
Existing 2x4 garage truss storage
(OP)
Gentlemen: There is a 2x4 roof truss system over my garage I plan to use for light storage. I am a Product Research Engineer and know little about truss loading, but the geometry of the truss system looked very good, so I proceeded. Although I am a Solids CAD designer, my youngest son drew the attached for me, so I'm going to use it to explain what I've done. What are your thoughts and opinions?





RE: Existing 2x4 garage truss storage
RE: Existing 2x4 garage truss storage
RE: Existing 2x4 garage truss storage
RE: Existing 2x4 garage truss storage
If your anticipated loading is going to exceed 20 PSF or if your home is older I recommend contacting a structural engineer in your area to review.
RE: Existing 2x4 garage truss storage
Beiswenger Research
http://www.beiswenger.com
RE: Existing 2x4 garage truss storage
Beiswenger Research
http://www.beiswenger.com
RE: Existing 2x4 garage truss storage
RE: Existing 2x4 garage truss storage
Beiswenger Research
http://www.beiswenger.com
RE: Existing 2x4 garage truss storage
Beiswenger Research
http://www.beiswenger.com
RE: Existing 2x4 garage truss storage
2. he may be right on the 43 inch thing, but jdgengineer above made a good observation as to the age of the house and the relevant codes at the time, suggesting the possibility that the trusses were designed prior to that 43" detail being inserted in the code, and therefore your trusses not being designed with that capacity. i do not know on this one, just trying to make a helpful observation. if i was your engineer, i would research this exactly.
3. was your engineer appraised as to the age of your trusses?
4. you're assuming the truss manufacturer built it to code, which is not unreasonable, but i'd work out that age thing first.
5. i really would avoid drilling bolt holes through that bottom chord. i am thinking you may be reducing the capacity of the truss on the order of 10% to 20%.
6. any reason why your builder is recommending reinforcements and your engineer is not?
7. 20 psf is not a lot. i tried to look up the psf weight of a box of books but couldn't find it quickly, someone else will have it. 42", 3 1/2 feet of somethings is a lot heavier than 3 1/2 feet of other things.
8. last time i strutted my stuff as an engineer over my wife's objections, it broke.
RE: Existing 2x4 garage truss storage
Beiswenger Research
http://www.beiswenger.com
RE: Existing 2x4 garage truss storage
RE: Existing 2x4 garage truss storage
Roof trusses, as you show, the additional loading would more often need the truss plates at the bearings and bottom chord splices repaired. Possibly a 2x addon in the panel of additional loading.
Personally, I prefer to use nails/screws repairs and not bolts for wood trusses.
As for will the trusses fail, that depends on how much load you add to the trusses. Whether the trusses will see the code maximum design load at the same time is also a concern.
Garth Dreger PE - AZ Phoenix area
As EOR's we should take the responsibility to design our structures to support the components we allow in our design per that industry standards.