Green roof live load
Green roof live load
(OP)
ASCE 7 specifies 100 psf live load for special purpose roofs. Would you consider a "green roof" to be a roof garden as noted near the end of chapter 4 such that the special 100 psf live load is required?
For this puropse let's assume that people are not meant to walk on this roof; it's only meant to be green without access for the public or assembly. The garden roof will be similar to these. We don't know which has potential for selection at this point.
For this puropse let's assume that people are not meant to walk on this roof; it's only meant to be green without access for the public or assembly. The garden roof will be similar to these. We don't know which has potential for selection at this point.






RE: Green roof live load
A commonly used value for the weight of soil is 125 PCF.
Seems like 100 would be kind of low.
RE: Green roof live load
RE: Green roof live load
that is DL not LL. We recently did something similar, and we only used the snow drift load. We used the masimum drift load everywhere on teh green roof (it was around 75 psf.
If people aren't meant to be up there, it seems hard to justify a 100 psf LL.
RE: Green roof live load
RE: Green roof live load
What happens 15 years down the road when someone decides do add a meager 4" of soil to revitalize the garden? That's over 40 PSF load you hadn't considered.
RE: Green roof live load
As stated above, it seems difficult to justify special roof loading of 100 psf live load if there is no access to the roof, but then I've been wrong before. That's why we have eng-tips! What would be great would be some literature convering this topic.
RE: Green roof live load
I didn't find this earlier because we don't use the 2006 IBC in my state and the ASCE 7 does not have a corresponding section.
This came about because a coworker is saying we should use the 100 psf for special purpose roofs. I'm interpreting this requirement to be based on assembly and not applicable where there is no access for assembly.
What do you think?
RE: Green roof live load
RE: Green roof live load
engineered soil is expensive. dirt not so much. I have heard of (haven't been involved with to my knowledge) contractors replacing the engineered soil with regular dirt to pad their bottom line. Regular soil is as much as three times heavier than the engineered stuff. As someone else suggested, long term maintainence could force small amounts of soil to be added later without the guidance of a complete design team. I would be overly cautious with a green roof design for loading as there are many variables not neccesserily under your control.
RE: Green roof live load
RE: Green roof live load
I'd be less worried about a possible load from occupants and more worried about the landscaping material. Just the water soaking into the material when it rains might exceed your rated "occupant" live load.
RE: Green roof live load
RE: Green roof live load
I would be conservative if it were up to me in estimating the soil loads. The question I'm having relates more to a colleague getting too caught up in terminology, imo.
The project in question isn't mine but I am trying to offer some advice.
RE: Green roof live load
If people can go up there, then its a garden. 100 psf LL
A garden is something people interact with, landscaping is not. Hope you straighten you college out.
RE: Green roof live load
RE: Green roof live load