Solar panels are around 3 lbs per square foot. Wet snow is 20 lbs per square foot per foot. Around here our roofs have to be designed for 30 psf.
From: Bill Prince via Af Sent: Thursday, December 18, 2014 10:52 AM To: [email protected] Subject: Re: [AFMUG] rooftop weight study? Concrete blocks are 8x16, which is 128 square inches, or about 0.9 square feet. The blocks I've weighed are closer to 35 lbs. (they used to be closer to 40 lbs., so maybe they aren't as "robust" as they used to be?). Dunno. At any rate, each block is going to be close to 39 lbs. per square foot. On a 3x3 we use at least 4 blocks, but usually more like 6 blocks. At 6 blocks on a 3x3 non-pen, I get around 23 lbs/square foot. So it depends on the area of the mount, how many blocks you're using, and probably where you source your blocks from. -- bp <part {dash} 15 {at} SkylineBroadbandService {dot} com> On 12/18/2014 8:52 AM, Eric Kuhnke via Af wrote: I don't think a 10'x10' NPRM (100 sq ft) weighs a total of 5000 pounds with concrete blocks. 50 lbs per square foot? I don't think so... If you have one of the small 3'x3' non penetrating mounts (9 sq ft) and put six 25 pound 16" length concrete blocks on it, that's 16.6 lbs per sq ft. On Thu, Dec 18, 2014 at 7:48 AM, Jon Langeler via Af <[email protected]> wrote: Non-pen mounts with block and antennas. Probably closer to 50lbs per foot. Anyone know a reasonable PE? Thanks Jon Langeler [email protected] > On Dec 18, 2014, at 9:36 AM, Chuck McCown via Af <[email protected]> wrote: > > Many jurisdictions allow 3 pounds per square foot additional load without additional engineering. > > -----Original Message----- From: Jon Langeler via Af > Sent: Thursday, December 18, 2014 7:09 AM > To: [email protected] > Subject: [AFMUG] rooftop weight study? > > We've been asked to provide a study of rooftop weight allowances in order to install a bunch of rooftop mounts. Has anyone else had to do this? Any info or good engineering firms to recommend? > > Jon Langeler > [email protected]
