pergola to steel frame roof trusses/top plate Sooooooo.... Little embarrassing this.
In the last ten years I have put up countless pergolas and completed minor and semi major renovations to many homes. And have only recently come across my first steel frame job.
Principles are all the same, this I understand, the issue I'm having is with attaching a Fly Over Pergola to top plate and roof truss on said steel frame home..
I feel like I'm missing something extremely basic and its doing my head in.
House is approx 2 years old and is of light gauge steel frame. Customer wants a raised deck so this means raising the roof of the pergola, hence Fly over. These are easily done with timber by using an extenda bracket or something similar. None of the specs available on these products say anything about attaching to steel.
Are these types of products able to be used on such thin gauge steel? Can i reinforce the section I'm attaching too with timber to give me a better purchase? Will putting holes in this stuff weaken it?
None of the chippies I know want anything to do with steel frames, not even to answer questions. Its like I'm asking them to hum me Beethoven's 1st in g minor (not even sure if this is a thing)
Any experienced info on this would be appreciated as I'm
As you have been doing this work previously you should be aware that any load at the top needs to be transferred via the framing down to the footings, and the footings need to be sized to suit the load.
Unless the steel frame has been designed for the point load that extends brackets will place on it then you will need to install suitable support to transfer the additional load down into the footings.
load transfer isn't the issue Droog. Of course what you r saying is correct, but since its a truss roof the wall is already designed to withstand point loads at truss points. Usually far exceeding the actual loads present. My question was with regards to the actual fixing of brackets to the Top plate/Truss being that they are of thin gauge metal that establishes its strength from its contour design rather than its solidity. Screws could therefore rip through and/or damage that structural integrity.
I thought I made that clear. My Bad.
This engineering document only mentions attaching to timber.
http://www.roofextenda.com.au/re/eng...tions-core.pdf
I suspect you'll need to talk to the frame manufacturer.
And I suspect you may be right r3nov8or. Best prepare myself to be stonewalled and fobbed off.
Exactly my point that I was making. The steel framing system is engineered for the loads at the points where they are attached, if you now want to attach roof extenda’s the frame needs to be engineered for that load at the point of attachment. The engineering document will contain the method of attachment for these brackets, the same as the existing frame engineering detail where and how the trusses attach to the wall frame.Originally Posted by chippi
Brackets of this ilk attach not only to trusses, but to top plate at truss load points. i understand what u are getting at but its my educated opinion (engineering draftsperson by trade) that the load offset, along with the extra load for this pergola roof at these points will be negligible and transfer will be more than enough.
If you have assessed that the frame has sufficient capacity for the additional load imparted by the new structure and the attachment point is the top plate truss junction then I would suspect the attachment would mirror the truss / wall frame junction connectors.
Not an engineer so only an educated guess. ��
... and don't forget about additional uplift
The issue will be the drilling and bolting of the extenda brackets, not the extra load that as you say will be within tolerance.
I would add timber to the attachment point to be safe. Could do with steel but probably too much mucking around.
Real knowledge is to know the extent of one's ignorance
Confucius
Does the truss have a plate / web that the Extenda bracket can be bolted to?
Load on the LW steel used as the top plate could be spread using a combination of plate washers/plus an extra layer of LW steel section but I see that though bolting to the steel truss as a problem. Not a builder or engineer; I'm just seeing a problem there if these is nothing to bolt through.
Will need an engineer perhaps? Also lots of short steel tubes so the LW steel sections are not compressed when the bolts are tightened
"A big boy did it and ran away"
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