Repair a Single Cut Web member in a Howe Truss roof 3

[sdpnme3]

I discovered, 15 years later, that a contractor who installed a whole house fan cut one of the web members out in order to install a whole house fan in our attic. Now I need to fix it to sell the house.

This thread ( thread507-476224 ) was an excellent reference similar to what I’m facing where there were three members cut ( I only have one ) In it there were a couple references to adding a distribution member spanning the two good vertical members just adjacent to the cut web members. I guess I don’t understand where the best location of the distribution members should be, closest to the roof or at the bottom of the truss sitting on the top of the ceiling rafters. Or maybe both? Also wonder if there are any thoughts on running a new web member to the center vertical but at a different angle and putting a vertical member to support it midway.

 

[Greenalleycat]

There's not enough information here to be able to say what you should do, and given that you have a 'computer' tag, I'm guessing this is more of you asking for free advice
If you're trying to sell the place then just do it properly. Get an engineer to specify a fix and have the paperwork to back it up.

 

[jerseyshore]

I see this type of stuff often. Going to a house tomorrow that they apparently did this to a bunch of bottom chords.

With just this one member, not a big deal. You could do a similar distribution member that was discussed in the previous thread. Put it just above the bottom chord at the base of the vertical and if it was me, I'd have it span 2 trusses in each direction (so 5 trusses total). I'd also add a couple of purlins at the top of the vertical to the adjacent trusses.

A new web would be helpful too, especially from a visual standpoint to make the buyers feel better about the repair. Just run a 2x on either side of the existing center vertical (slightly higher up so it misses the fan) and fasten it all together.

 

[LittleInch]

I'm more interested in why you want air from your loft blown around or into the loft....

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[JStructsteel]

Its more likely the best way to fix is run a diagonal down to each other truss.
Not sure your local, could depend on the loading

 

[sdpnme3]

Thanks for the quick responses and great posts.

I do want to make it right for the new owner, so thank you greenalleycat, you are correct I am looking to do the work myself and value the advice that was provided by jerseyshore and yourself. At your prompting I’ve sought out structural engineers in my area ( Palatine, Il.) who might be willing and able to advise. These days it’s hard to find anyone who is willing to take on such a small job, but I don’t want to start another discussion on the state of who wants work and who doesn’t. In response to littleinch, the whole house fan draws air through the house and up into the attic and as you know forces it up there, so at a molecular level I’m not sure what’s happening in the attic, but after a hot day and when the sun goes down, drawing air through the house with the windows open? Well it just feels good. . I know I’m just a computer guy, but really enjoy reading the content here and truly do respect the engineering that’s done to keep a roof over my head and the walls standing against the forces of nature. You guys ( and gals ) rock!

 

[sdpnme3]

Thanks Jstructsteel for taking the time to respond on this. Much appreciated.

 

[LittleInch]

Well I guess there is somewhere for the air to go.... A big grill somewhere?

I'm still not sure what the pictures are and it would be much better to have a couple of sketches of what an undisturbed truss looks like and what your butchered truss looks like.

What is that second picture all about? Existing truss element or something else. Very unclear.

At the least having a good dimensioned drawing and some details of the connections will be very useful for who ever you get to do some sort of design.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[jerseyshore]

Looks like the second picture is the bottom of the next vertical where the old web member was cut/ removed from the joint to make space for the fan.

 

[LittleInch]

Actually the bottom chord is still there when you look at the top photo as it's what the fan sits on.

So ist only the diagonal member which has been removed?

Drawing would still help....

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[IRstuff]

Your 2nd picture seems to imply missing webs where the beam under your knee goes, since that beam seems to go across multiple trusses.

A wider angle view would certainly provide more context.

TTFN (ta ta for now)
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[jerseyshore]

Just got back from a house today with this exact problem, except it was both webs on each side of the center vertical of EVERY TRUSS. Current owner cut it out because "he needed more storage space" (and apparently loaded the hell out of it too, cracks everywhere). So looks like I am going to be drawing up my own repair detail similar to what I described above.