Fix for Cut Truss Web Members 2

[Simba13]

Morning All,

I wanted a second opinion on how to approach repairing some cut roof truss web members. See the attached photos above (I wish I had gotten a few better pictures but you can get the gist), web members of three roof trusses (24" O.C.) were cut to make room for a little alcove in the master bath for a washer-dryer set. We've been asked to design repair modifications for this and other modifications done to the house. I'm not looking for specifics here, more of a high level approach of how to go about fixing this. I've thought about sistering larger members to convert it into a rafter roof in just this region or building a frame around the cut region to distribute the load (somehow...). I'm curious if any of you have seen this before from crazy DIYers and how you approached the design.

Thanks,

 

[oldestguy]

I am under the impression that once you cut the trusses and moved the equipment in you would replace all the members cut. Which is it?

 

[KootK]

I had thought that you were running the 2x12 the full length of the trusses and using them to support the trusses. Under that arrangement, your top chord would probably have the same vertical support that it did in it's original condition (same top chord panel points). As such, if that assumption is correct, there'd be no need to add additional support for the top chord.

I'm confused by your 8', 2x12 approach. As it stands, the missing truss diagonal compromises the triangulation of the trusses and reduces their carrying capacity massively. Beefing up only the bottom chord only under the laundry machines and "stiffening" the top chord doesn't address that primary need in my opinion.

 

[KootK]

Similar to OG, are we dealing with truss bottom chords that have already been cut as well?

 

[Simba13]

When I go back I will confirm, but I believe that only the diagonals shown were cut. This has caused a noticeable sag in the roof. I don't believe that the bottom chord was cut. I'm just trying to restore stiffness and eliminate the sag created by the cut diagonals. Does that make sense? Obviously what I'm proposing might not be enough to restore the truss action, just brainstorming.

 

[dauwerda]

I am having a very hard time understanding the full picture of what is happening here. Are these "attic" trusses with living space in the middle portion? The owner then expanded the living space in one portion by cutting out truss webs and building a new wall (essentially the bottom cord of the trusses are the floor joists for the living space)? Or is the living space a full framed second story (supported by beams and floor joists) and the picture you are showing is mono-pitch truss that terminates at the living space?

 

[Simba13]

Ok, so I just ran through this with my boss. A second site visit is going to need to be performed, based on the roof line and some other details it looks like this portion of the house (the garage) is an addition to the house and it's kind of unclear on how this roof is framed. Sorry for the confusion, I'll update you all when I know a bit more.

 

[jayrod12]

Fixing the sag might not be in the cards. You could prevent further sagging, but fixing it would require jacking. I'd advise the homeowner that the sag is permanent, but after the repairs should not become worse.

 

[Simba13]

dauwerda I believe you've got it. I spent the better part of the morning grappling with that exact question. The answer to the first, "Is there living space in the middle portion?" is yes, that's where the master bath is but again there has been so much modification to this house far beyond the cut trusses that this isn't where the master bath was when the house was built, it was more of a very large laundry type room over the garage (my boss thinks that even the garage was an addition because of the way the roof frames in, it was there when the client moved in however).

The second question "Did they expand this space by cutting the truss diagonals?" is also yes.

The last issue, since this is so irregular, is what is the floor system in the master bath now, that's one of the reasons I need to go back. I can't imagine any human stupid enough to use the bottom chord alone as a full living space flooring system, but there's also a steel beam below it in the garage so maybe they thought that would be enough...

I would post pictures of how weird this roof is from the outside but I think posting a clear picture of someone's house is kind of a no-no. But once I go back and I'll update you all.

 

[KootK]

If you're able, I'd recommend posting a sketch of the truss profile in its entirety, approximately to scale. Nothing I've seen in your photos so far suggests to me that these are legitimate attic trusses. Like you said though, that steel beam may factor in.