Sloped standing seam metal roof parallel to and over existing steel joists and metal deck
Sloped standing seam metal roof parallel to and over existing steel joists and metal deck
(OP)
All,
The owner and architect want to place a standing seam metal roof over an existing conventional bar joist and metal deck roof system. The slope of new roof would be parallel to the joists. Joists span 45', are spaced 4' oc and have panel points about 4' oc. Narrow rib metal deck with 5" of insulation and a BUR. I am looking for framing suggestions.
On past projects with shorter spans and bearing walls, I have used light gauge trusses at 8' oc and hat type purlins at 4' oc or so to support the standing seam roof. In this case, providing a structure over the existing structure seems like overkill. The existing structure is adequate for the loads. I have considered running beams perpendicular to the joists at 4' oc with stub columns down to the joists. Lots of little pieces and cutting holes through the deck to weld the columns down for up lift. Architect suggested bearing walls at 4'oc cut down to the deck but there would still be point loads at each joist and uplift connections to deal with.
I assume this has been done many times before and I would like to avoid reinventing the wheel. Making budget would help too!
Thanks
Ken
The owner and architect want to place a standing seam metal roof over an existing conventional bar joist and metal deck roof system. The slope of new roof would be parallel to the joists. Joists span 45', are spaced 4' oc and have panel points about 4' oc. Narrow rib metal deck with 5" of insulation and a BUR. I am looking for framing suggestions.
On past projects with shorter spans and bearing walls, I have used light gauge trusses at 8' oc and hat type purlins at 4' oc or so to support the standing seam roof. In this case, providing a structure over the existing structure seems like overkill. The existing structure is adequate for the loads. I have considered running beams perpendicular to the joists at 4' oc with stub columns down to the joists. Lots of little pieces and cutting holes through the deck to weld the columns down for up lift. Architect suggested bearing walls at 4'oc cut down to the deck but there would still be point loads at each joist and uplift connections to deal with.
I assume this has been done many times before and I would like to avoid reinventing the wheel. Making budget would help too!
Thanks
Ken






RE: Sloped standing seam metal roof parallel to and over existing steel joists and metal deck
BA
RE: Sloped standing seam metal roof parallel to and over existing steel joists and metal deck
RE: Sloped standing seam metal roof parallel to and over existing steel joists and metal deck
RE: Sloped standing seam metal roof parallel to and over existing steel joists and metal deck
I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.
RE: Sloped standing seam metal roof parallel to and over existing steel joists and metal deck
I can check but new slope should be about 1:12. For 45' span, mono pitch, 45" of slope. Slope will be parallel to the existing joists for the main part of the roof. Ends will have a hip but whatever solution we use for the main part can be adapted for the ends.
RE: Sloped standing seam metal roof parallel to and over existing steel joists and metal deck
RE: Sloped standing seam metal roof parallel to and over existing steel joists and metal deck
Neglecting the temporary waterproofing issue of a slot cut through the roof every 4', I still have structural issues with the bearing wall. A strip of deck 6" or 1'-0" wide will not support 4' of trib roof therefore I would still need something to span between joists, a deep leg track might work. The point load would need to be transferred down to the joists. Cut out deck and extend a couple studs? Attach for uplift? We can't cut through the deck for the full length or we loose the diaphragm. A bearing wall might be the best solution, I am just not there yet on how to make it work.
RE: Sloped standing seam metal roof parallel to and over existing steel joists and metal deck
Also on the waterproofing aspect. Why the standing seam roof if the flat roof is expected to be the actual building envelope layer. Why not just replace the flat roof and leave it?
The owner has to accept that this is not a cheap modification.
RE: Sloped standing seam metal roof parallel to and over existing steel joists and metal deck
Jimstructures
RE: Sloped standing seam metal roof parallel to and over existing steel joists and metal deck
RE: Sloped standing seam metal roof parallel to and over existing steel joists and metal deck
RE: Sloped standing seam metal roof parallel to and over existing steel joists and metal deck
RE: Sloped standing seam metal roof parallel to and over existing steel joists and metal deck
Thanks again.
Ken
RE: Sloped standing seam metal roof parallel to and over existing steel joists and metal deck
What happens when the roof actually starts to leak? They've got to rip off the standing seam roof and your support structure to make repairs? That seems ridiculous.
RE: Sloped standing seam metal roof parallel to and over existing steel joists and metal deck
RE: Sloped standing seam metal roof parallel to and over existing steel joists and metal deck
RE: Sloped standing seam metal roof parallel to and over existing steel joists and metal deck