Soil for Green Roofs, load capacity?
Hi,
I’m hoping to do some green roofs eventually on a building I am part owner of here in Baltimore and I’m trying to figure out if the added load is acceptable with the existing framing.
I will eventually check with an engineer but trying to get a rough idea for now.
The roofing material will be .060 epdm over 1/2″ fiberboard, the roof deck is 3/4″ ply. The joists are 2×10 – 16″ O.C. unknown species at this time. The joist span varies a bit but roughly 15 feet.
The soil mixture is a special lightweight mix that is 54 lbs per cubic foot dry and 86 lbs wet. The soil layer will be 3″ so that makes the weight 13.5 lbs per sq. ft. dry and 21.5 lbs wet.
I don’t know enought about live loads and dead loads to know if that is acceptable or not.
Any thoughts would be greatly appreciated!
Thanks,
Tom
Replies
Hi Tom, snow and live loads here are considered the same. Assumption being that if there's snow, nobody'll be up there. We plan for 50 psf. Oddly, the one engineer possessing a stamp that I needed specified 75 psf, which was later reduced by our building dept.
Your engineer is going to be very interested in what's holding up those joists. I once tried to do something with an older roof and got shut down by the number of nails.
I don't deal with wood loading so will leave that to somebody else. Total load would be live plus the weight of the roof itself, in your case wood plus epdm plus your 21.5 lbs. The dry weight isn't important.
You getting a permit? They'll know.
PAHS Designer/Builder- Bury it!
Hi VaTom,Yes eventually permits and before that I'll hire an engineer to look it over. My gut instinct (and wish) is that the load is within limits but
thought I'd check in with the braintrust here on at least a WAG.The structure of the building is brick for the exterior walls and a heavy post and beam structure interior to support the joists.Someday there will be a lot of green roofs!Tom (Baltimore Tom)You Don't Know.
You Don't Want to Know.
You Aren't Going to Know.
You the same guy who brought up green roofs quite awhile ago? Baltimore I remember. If nobody else shows up, I'm pretty sure there are load tables out there.
Every house I've built has a green roof. (Both of 'em.) Here's mine:PAHS Designer/Builder- Bury it!
Yup, it's me again!
Still dreaming of the day when I have a little green roof.
Thanks for the photo.
Hey, could you send some more showing part of the house and roof!
Be great to see a bit more.Baltimore TomYou Don't Know.
You Don't Want to Know.
You Aren't Going to Know.
http://paccs.fugadeideas.org/tom/index.shtml is a page put up by a guy in Florida about our place. Includes pix of the roof assembly.
Or if you're down this way (Charlottesville), give a yell.PAHS Designer/Builder- Bury it!
Pretty neat place Tom, I will try to swing by if I'm ever down that way.
Let me extend an invitation to you as well.Pretty much the opposite in environments. I purchased a 66,000 sq. ft building in Baltimore with 5 partners about 3+ years ago and we've been cleaning it out (70+ dumpsters 30 cu.yds), fixing it up and renting studios to artists. We're also developing lofts for ourselves as well.
It is a down at the heels urban area but much of Baltimore is rebounding at this point. The dream is to have green roofs on all the flat roof areas someday. About 14,000 sq. ft. total. But it's way down the road.I'll put up a few pics later....You Don't Know.
You Don't Want to Know.
You Aren't Going to Know.
We used to visit a friend in little Italy there. The inner harbor was interesting. Your building's in the neighborhood?
A previous employer here bought 60k sq ft of industrial space and did similar. Those 50 kitchens got real old to make, again, and again, and again..... No green roof.
We lived inner city once (Denver) in a commercial building. For us, this is better.
Bring on the pix.PAHS Designer/Builder- Bury it!
A Google on "green roofs" (images)
http://images.google.com/images?sourceid=mozclient&ie=utf-8&oe=utf-8&q=%22green+roofs%22
Switch to "web" for site links
"We learn from experience that men never learn anything from experience."
George Bernard Shaw
Edited 9/6/2005 6:54 am ET by Newf