Structural columns or not?

[engineerfin]

​Florida structural engineering question. This house has rotten wood columns. 6 columns and all are hollow, not structural, I think. The distance from the brick wall to the fake column lintel is 6'1, wood frame house, slab on grade with the exception of the porch. Are the columns holding the lintel or are the truss tails holding it. The thing that bothers me are the hurricane straps are at the lintel. Thats fine and dandy but the up lift is troublesome. Even when new.... a few toe nailed columns to the deck boards wouldn't hold squat. What am I missing here.

 

[engineerfin]

more pics

 

[engineerfin]

and another

 

[msquared48]

I do not think these are "fake" columns with that 8 foot or so span and the brick fireplace.

I think the area over the porch is framed with jack trusses that bear separately from the main roof trusses and are broken / married over the exterior wall.

The brackets are placed to resist the uplift from the wind at the end of the truss.

Mike McCann, PE, SE (WA)

 

[Ron]

The hurricane clips are installed incorrectly...not properly nailed. Inspector should have caught this. What part of Florida are you in? I'm in Florida as well and practice throughout the state.

 

[engineerfin]

Ron, those are not hurricane clips. Were not put into florida law until 2002. Miami dade used them after andrew in 1992. This house was built in 1989. I think the clips you are seeing are simpson clips that are holding up the fake wood lintel. msquared48, I understand the jack truss thing, not really seen one that is cantilevered. 6' is no big deal but in the corner its like 12'. That hip jack is just hanging out there, cantilevered. I have included some more pics of a hip girder in the corner and the jack truss. So I understand the uplift on the jack but I dont see a strap on the base wall plate to truss. Guess because it was build before 1992. So the truss resists the uplift but the trusses lift off the wall, not good. Then because its cantilever there is a down force so the columns might be helping a bit, right.

 

[engineerfin]

more pics

 

[TEDstruc]

I am in agreement with Msquared. If I were working on this I would assume columns as structural with beams spanning between columns.

I did a quick google search, and found some decorative porch columns that are specified by the manufacturer as having a 14,000 lbs bearing capacity (for 10" diameter x 8ft long). The takeaway here is that decorative porch columns can be structural.

https://www.pacificcolumns.com/php/...08ATPSATUTU&leadSource=architecturaldepot.com

 

[engineerfin]

I called a structural PE and he told me that "all single story houses will have non-load bearing exterior columns". Is that dumb or what.

 

[msquared48]

BS. Pure BS.

Mike McCann, PE, SE (WA)

 

[gte447f]

I also agree with msquared48, I doubt if the porch perimeter beams and columns are "fake". Jack trusses are not usually cantilevered; they are usually simple spans between a girder truss and a bearing wall or in this case a beam at the edge of the porch. Also, the idea that the hurricane clips are actually being used as hangers to support the the fake beam is quite a stretch if you ask me. Remember, this was probably framed by a Bubba; they like to keep things simple, which is a good thing. Turning the typical load path upside down... I don't think so.

 

[gte447f]

Also, I used to always assume that those decorative columns were simply wraps and that there was a structural column like a 4x4 inside the wrap. But, as Tedstruc pointed out, some of them are supposedly manufactured to support structural loads. How you are supposed to make a beam connection to the top of them I don't know, but that is a different story I guess.

There is a double decker porch in my neighborhood that is supported by these type columns and they are visually buckling. I had assumed it was just the decorative wrap was picking up unintended load and was buckling, and that there was a structural column inside, but maybe not. Does this mean I need to go knock on my neighbors door?

 

[XR250]

Not to hijack this thread, but i ran across a similar situation recently where the trusses were designed to span from the porch beam all the way to the rear wall (about 36 ft.). Turns out, the beams were fake. I guess the contractor assumed they were intended to bear on the front wall and cantilever over the porch. Lots of sagging has occurred in 30 years as there were no web members in the truss near the front wall. Two entire apartment complexes worth of this!

 

[msquared48]

I have too, but unless you can verify that in the field, I would not assume it.

Mike McCann, PE, SE (WA)

 

[charliealphabravo]

There are clear provisions for bearing at the interior porch wall with the vertical chord but that does not necessarily mean that the trusses cantilever over the porch. It more likely means you have 3 point bearing, including the porch beam.

 

[azcats]

The house I grew up in had a layout similar to this. I remember one day bumping into one of the posts with my bike and it just kinda swung out of the way. There was absolutely no bearing on that post and deflection in the main span had lifted the porch beam and in turn the post. No idea if it was actually designed that way or not.

 

[engineerfin]

Here is a pic of the truss bearing web at the brick wall.

 

[engineerfin]

pic at corner of brick where porch gets large. There is some type of connector there.

 

[engineerfin]

Columns not touching deck due to rot.

 

[BridgeSmith]

Just because the column isn't currently bearing on the deck, doesn't mean it isn't supposed to. It also doesn't guarantee the columns will not be needed for support in the future. Unless you're prepared to do a loading calculation and a full structural analysis of the trusses, I'd suggest restoring the original capacity of the columns, either by repair or replacement in kind.