Metal roof deck for a pathway/walkway 1

[WWTEng]

Theoretical question: Typically the metal roof deck (for example 1.5x20ga, spanning 5’ c/c) seems to have decent load capacity. If the architect shows roof pavers of some sort to provide a walk way across the roof, and if the deck has capacity to handle and dead and live loads, could it be used for that purpose? Or is there something in the codes/practice that requires you to provide concrete on metal deck for such application.

 

[WWTEng]

Any input?

Thanks.

 

[BAretired]

The only problem I can think of is that the deck would be exposed to rainwater. Should be okay if galvanized.

BA

 

[MiketheEngineer]

Agree w/ BA. JUST verify loads, etc

 

[hokie66]

How would the deck be exposed to the weather? Aren't the pavers placed above the roofing?

 

[BAretired]

Yes, but there is nothing to stop water from flowing through the joints between pavers.

BA

 

[hokie66]

That's fine. The water is still above the roofing, which is above the deck, I think.

 

[BAretired]

I thought the OP wanted to use the deck bare with just pavers over it. If the deck is protected by roofing then I agree with hokie.

BA

 

[hokie66]

To me, "metal roof deck" is always the substrate for insulation and/or roofing. If it is bare, it is "metal roofing". For metal roofing, you wouldn't use pavers, as they will move around. On metal roofing, metal walkway sections are used, and they are connected to the roofing.

 

[WWTEng]

BA, Hokie: The architect's section showed some roofing (3.5" insulation, 1/2" gyp board, 1/2" fiberboard with some other layers if roofing topped with 1.5"-2" thick pavers. The total DL comes out to be less then 45 psf. IF there is goung to be a promenade over the pavers, the total load would be 105 psf. So it seemed to be that 1.5x22 ga should technically work since it has the capacity. And of course I would use galvanized deck. I guess the only problems I see with the application is that the roof might be a little "bouncy" and it could also be difficult to dampen the sound transfer below the deck.

 

[hokie66]

If this is for occasional use as a walkway for accessing equipment on the roof, the solution sounds appropriate, as long as the roofing is robust enough and the roof drainage is adequate. The word "promenade" bothers me, as that suggests more frequent and intense use.

 

[ztengguy]

I used to see pavers all the time to define a walkway on a roof. They didnt cover the whole roof, just where the walkway was, I assume to prevent people walking on the ballast. If he wants to cover the whole roof with pavers, and the roof can handle it, so be it. I would only be concerned about water sitting under the pavers, never really getting dried out like a roof would that has ballast. Not sure if this affects roof warranty.

 

[WWTEng]

Hokie, Ztengguy: The arch. has decided not to create any promenades over the roof. Part of the reason was that I was pushing for us to design for public area (100 psf), plus the cost came too high. So he still wants to do pavers but only as alternate with no public access. I did bring up the issue of drainage and will let him deal with it from here on out.