Joists and reinforcement around large rooflight

[health mechanic]

I have a 3m x 0.45m flat roof skylight on ground floor within a small width flat roof ~ 80cm ( 2nd floor setback behind parapet above). Engineer has specified doubling joist on width and longitudinal run, builder on widths has tripled for further strength (as per photo) But I can't reassure myself whether on such a large run the triple joist will take weight without significant deflection. There are 7 ~ 16cm lengths of cut joists/noggins in-between as per photo, one side sit into steel and the other resting on inner leaf of brick work. These are simply nailed in. Are these too short a section to provide further structural integrity when loaded or are purely to dress the roof.

 

 

 

 

 

 

 

 

 

 

[Nickfromwales]

I wouldn't worry about deflection here tbh, as the weight will ne supported largely at the 4 corners. 

The only thing I don't like is the fact it's rather 'loosely' nailed, whereas I would have used construction screws to join this lot up. Would have helped to stiffen things up considerably.

[Bonner]

As @Nickfromwales said, don’t worry too much about the engineering, be more concerned about the execution. Is it done according to engineers specification? If in doubt, send pictures to SE for comment.

[health mechanic]

Yes engineer happy...but couldn't get over the noggins being loose. I thought screws were not as good as nails here due to lack of lateral strength?