kmart30
Structural
- Apr 28, 2016
- 183
Roofer is trying to retrofit a new standing steam metal roof over an existing metal roof over Z purlins. We are adding about 2.5 to 3 psf in DL but I cant get them to check out. However, when I reference load tables from a local manufacture for these purlins it checks out. Its not a lot of load we are adding but I know there isn't usually any "fluff" designed into these PEMB's. I know these purlins typically get designed as a system with multi-spans and laps at supports for added moment capacity but still cant get it to work even though its close. The new roof system will have smaller z shape like purlins fastened to the top of the existing ones with the new panels attached to these. I know this will also stiffen up the existing purlins but I am not sure how to incorporate this into my calcs.
Also, the code allows up to an additional 3psf of load to existing roofs without having to check the capacity of the existing supports. The roofer knows of this code as well so if I go back and say sorry no dice it could really stir the pot up. What is the play here?
Also, the code allows up to an additional 3psf of load to existing roofs without having to check the capacity of the existing supports. The roofer knows of this code as well so if I go back and say sorry no dice it could really stir the pot up. What is the play here?