Miami - Broken Roof Trusses

[dhoward26]

The company I do some work for has a one story building in Miami. Wood walls, and wood trusses. About (5) trusses have chords that are broken. The span isn't huge, only about 36 ft or so.

They are getting bids from contractors for doing the roof and truss repair.

My question is this: In Miami, is this something that would trigger an engineers stamp of approval to repair broken trusses with plywood gusset plates? I haven't had much experience down there with this, however, a recent truss issue in Oregon required my stamp of approval before the contractor could build.

Thanks.

 

[JedClampett]

Miami Dade County is very tough to work in. They require permits for everything. And their rules change depending on the phase of the moon.
I'd say call them, but you're likely to want to blow your brains out right after that.

 

[dhoward26]

Hahaha, thanks...I think I will skip the second part though!

I spoke with one of the contractors earlier and he said he does little truss fixes like this quite regularly in Miami and hasn't had any issues with the building department asking for engineered calcs. Seams a little surprising down there but every place is different.

 

[TXStructural]

Trusses are an engineered member, and as such, the design of repairs requires an engineered design. Having done quite a few of these, it is not as simple as one might think.

 

[woodman88]

Per the 2010 FBC Section (Can view for free at

http://www2.iccsafe.org/states/florida_codes/)

"2303.4.5 Alterations to trusses.

Truss members and components shall not be cut, notched, drilled, spliced or otherwise altered in any way without written concurrence and approval of a registered design professional. Alterations resulting in the addition of loads to any member (e.g., HVAC equipment, piping, additional roofing or insulation, etc.) shall not be permitted without verification that the truss is capable of supporting such additional loading."

So trusses are okay to repair by anyone as long as the repairs do not add additional loads, cut, notched, drilled, spliced or otherwise altered the truss?

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.

 

[woodman88]

Here is a link to one of the better articles on the basics of repairing wood trusses.

http://www.structuremag.org/article.aspx?articleID=797

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.

 

[dhoward26]

woodman88: Just reading through that section. Seams that a truss cannot be repaired in any fashion without written approval from a design professional.

 

[msquared48]

Jusdt wondering what broke the truss members... Boa constrictors missing the rats on the rat-runs?

Mike McCann
MMC Engineering

http://mmcengineering.tripod.com

 

[dhoward26]

I have no idea. It has apparently been like this for years. They will find out when they open the roof up I suppose! Rats, raccoons, opossums, snakes, homeless people...who knows.

 

[ron9876]

Like JedClampett said it is Miami and they are very difficult. Some areas (and inspectors/reviewers) are much more difficult than others.

But yes it should be engineered. I also wonder what would break the chords.

 

[msquared48]

Ar the chords, bottom I assume, broken at the center splice connector, or randomly at knots or diagonal connections?

Maybe an alligator was lifted into the sky by a tornado and dropped onto the roof a few years ago?

Mike McCann
MMC Engineering

http://mmcengineering.tripod.com

 

[MiketheEngineer]

The larger truss plate companies may help you. Contact Alpine or Mitek. For a nominal fee - they will design a repair and seal it.

 

[dhoward26]

Gathering more info. Apparently termites run rampant in this area. They replaced other roof trusses due to termites in a building about 30 ft away. Also, the trusses were replaced approximately 15 years ago after a fire. I'm assuming, at this point, termite damage at the joints and whomever looked at it thought these were broken chords. I'm waiting for pictures of the trusses and then taking a trip to Miami

 

[BAretired]

I don't think the authorities are being unreasonable in asking for an engineering seal on this work. Failing to do so would be seen as delinquent in carrying out their duties. I have seen a few examples of trusses repaired by contractors which would not have performed adequately under load.

Are you really going to repair broken chord members with plywood gusset plates?



BA

 

[dhoward26]

No, if it is a chord that is broken, I definitely won't do a splice. I don't have too much heart-burn in providing gussets at the connections. I suppose worst case scenario, I could add vertical members and diagonal members to the location of concern in a chord, analyze it in Risa, and then add gussets to other joints as necessary. I'm going to try to dig up the original truss design first though. I would think I could find it as they are only about 15 years old.

Might be easier to just replace the trusses. They are replacing the roof tile anyway, so to remove part of the old sheathing underneath and drop a couple trusses in might be the best way to go.

 

[msquared48]

Were the trusses originally designed for the tile load?

In this question is probably the answer. Seen it happen a lot.

Mike McCann
MMC Engineering

http://mmcengineering.tripod.com

 

[dik]

...any idea of why they 'broke'?

Dik

 

[Ron]

dhoward26....woodman88 is correct. Refer to Chapter 5 of the Florida Building Code-Existing Buildings. This gives the criteria for structural repairs.