Min roof slope

[BAGW]

Hi,

I am looking at the IBC minimum roof slope requirement for standing seam metal roof. IBC callouts for min 2% or 1/4" per foot. 2% exactly does not translate to 1/4" per foot. I understand this is more of rounding off to get to a nice number. So typically we follow 2% slope is that meeting the code even if the slope is slight shy of 1/4" per foot? Trying to understand the code. Is there a metric version of IBC, maybe the numbers there are closer to 2%.

Thanks

 

[KootK]

The difference between the two is only 4%. I'd pick whichever value suits you and not worry about it. I'm a 1/2" per foot guy myself but I never get to choose.

 

[JedClampett]

You better go into the manufacturer's literature. Check the fine print. I'd be surprised if a standing seam roof manufacturer would permit a 1/4" or 2% slope.

 

[structSU10]

The verbiage for ponding instability was expanded in ASCE 7-16 as well - it may not preclude a susceptible bay depending on framing direction. they state if the framing is parallel to the free draining edge requires 1 in / ft otherwise it should be investigated for ponding.

 

[straub46]

PEMB manufacturers routinely allow 1/4" slope for roofs with standing seam panels

Go Bucks!

 

[1503-44]

Note to self: Minimum slope must still be had after accounting for deflection of the beams and perlins holding up all that water ponding on top of them[pre][/pre].

 

[jimstructures]

For some Pemb's.

screwdown roof panel minimum roof slope of 1/2:12,

standing seam roof panel minimum roof slope 1/4:12,

Investigate ponding wherever appropriate or if required due to roof slope.

Both situations are checked.

Jim