David, that makes sense. The concern seems to be fastener pull out. Increased fastener spacing would increase the load on each fastener, hence tougher steel to hold the threads.
Phil, I assume the roof you refer to was adhered?
My experience has been in California, maybe this is different in high wind regions.
The engineer should consider wind uplift loads but in most cases this is not a real concern for the building sheathing and the roof structure. Thus detailed calculations of wind uplift forces may not always be calculated..
Architects are not in the habit of asking the structural engineer about wind uplift loads. I cannot recall being asked by an architect about wind uplift loads.
If the interior air pressure is positive and the structure and insulation is sufficiently porous this can result in additional uplift forces on the roofing which in turn must be resisted by the mechanical fasteners. gravel and pavers can mitigate these uplift forces.
Open buildings and overhangs are subject to higher uplift forces.
To John’s comments about adhesives in construction:
I used to be wary too. Until I took a look at the engineering of glass curtainwalls that use silicone adhesives for structural connections. The trick is surface preparation and working within tolerances.
My experience has been in California, maybe this is different in high wind regions.
The engineer should consider wind uplift loads but in most cases this is not a real concern for the building sheathing and the roof structure. Thus detailed calculations of wind uplift forces may not always be calculated..
Architects are not in the habit of asking the structural engineer about wind uplift loads. I cannot recall being asked by an architect about wind uplift loads.
If the interior air pressure is positive and the structure and insulation is sufficiently porous this can result in additional uplift forces on the roofing which in turn must be resisted by the mechanical fasteners. gravel and pavers can mitigate these uplift forces.
Open buildings and overhangs are subject to higher uplift forces.