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I'm getting ready to install drywall in my garage. In the process, I'm removing various nails and screws that the previous owners had used for hanging and storage. Basically I'm removing anything that is protruding from the framing. Running across the middle of the my garage ceiling there was a 2x4 that was screwed into the bottom chords of the roof trusses. It didn't seem like it was doing much: there was a noticeable gap between it and a couple of the trusses. Additionally it was only supported on one end by a short 1x1 and on the other a short 2x4, each of which were screwed to the sides of the top plates with only a couple screws. Its installation seemed like a hasty afterthought and it seemed to have no structural purpose whatsoever. I figured it was just put up there for hanging stuff and item storage even though it didn't notice any hanging hardware installed in it.

Upon removing it, however, I was concerned to see that it ran directly underneath where the two bottom chords that made up each truss were spliced together. My trusses have this type of design (credit Construction Concept Design Build LLC):

diagram of a common roof truss

My bottom chords are spliced together in the middle, directly under the king post. The 2x4 I removed ran directly below the splices. Was that 2x4 there to provide some kind of structural support? Should I keep it in place and butt my drywall up to it? My garage is 24 ft long, so each bottom chord is made up of 2 12ft 2x4's. Perhaps that 2x4 I removed was there to provide additional support for the trusses which otherwise don't have any support along that full 24ft length.

Here's a picture of one side of my garage where I removed the 2x4. You can see where it was below the splices as indicated by the indentation in the insulation kraft paper.

trusses with 2x4 removed under splices

Depiction of where the 2x4 was located: depiction of 2x4 location

Images from attic space. The first picture shows a plywood strip fastened to the trusses, spanning three of them. In the second, a door can be seen which is being stored up there. I moved it aside to get a good look at the middle of the trusses, above where the 2x4 was.

attic space 1

attic space 2

isherwood
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Ethan
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2 Answers2

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If your trusses are intact (no members have been modified and the connection gussets are still intact) then there is no need for the extra 2x4.

The trusses were, (or should have been) engineered at the truss plant to provide a roof structure designed to support any snow load common to the area.

Any additional structural support would come from members (2x4, 1x4) attached perpendicular to the truss webs and running from one truss to the next. This is common in areas where wind resistance is needed and would be prescribed for end trusses and run to the next 2 or 3 trusses. These braces would be needed at 2 or 3 points. A brace would never run under the bottom chord of a truss, unless this was a repair engineered for specific damage. That is not what you have. Bottom chords mated in the middle is not uncommon.

isherwood
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RMDman
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Those bottom 2*4 that you removed need to be put back pdq.

They are in tension when the load on the roof increases, like snow load. So, as the mass on the roof increases, those 2*4 stop the main roof timbers spreading and even pushing the walls out.

If, well when, you put them back you need to get an engineer to make sure you have connections sufficiently strong such that they won't rip out or cause the main timbers to fail.

Solar Mike
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