Florida/Orange county solar roof attachment requirements

[dirtysanchez]

Hi,
I few been lurking around here for a while and I'm planning on putting a 7k solar array. Spoke with my first solar contractor who advised me that Florida or orange county requires roof rail attachments every two feet or every rafter. It used to be every 4 feet but this was changed this year around March. This would be a lot of penetration points for a 25 panel array. Could someone with local knowledge comment on this ? Is this true ? I thought this was determined by the roof zone and rail manufacturer . Panels would be mounted in the lowest load zone right in the middle.

[Naptown]

Well you are in Hurricane country.
There are 2 rules (One's that I cannot comprehend) but I'm pig headed.

1) the AHJ is always right

2) If the AHJ is wrong refer to #1

Use flashings to minimize the leak potential.
Use the proper length bolts to bolt to the roof structure.

[dirtysanchez]

If my math is correct that's a 100 penetration points for a 39 inch panel. Bit scary I would only use flashing type mount but still that's 100 holes in my roof.

[fafcosolar]

Hi,
I few been lurking around here for a while and I'm planning on putting a 7k solar array. Spoke with my first solar contractor who advised me that Florida or orange county requires roof rail attachments every two feet or every rafter. It used to be every 4 feet but this was changed this year around March. This would be a lot of penetration points for a 25 panel array. Could someone with local knowledge comment on this ? Is this true ? I thought this was determined by the roof zone and rail manufacturer . Panels would be mounted in the lowest load zone right in the middle.

No way. Especially not in Orange County. In Southwest Florida where we have design wind speeds up to 172 mph, we can meet the wind load requirements with 4' spacing for roof attachments in Zone 1 & 2. The March date is referring to the Florida Building Code 2010 that went into effect on March 15, 2012 in Florida along with the ASCE 7-10 calculations for wind loads. While the wind speeds did increase for everyone in Florida, the ASCE calculation actually results in lower wind pressures in most areas. In fact, residential structures in Exposure Category B (inland) in Orlando should have 14% lower design pressures under the new building code. If you want more information here is an excellent description of the changes (http://www.floridabuilding.org/fbc/W...anuary2012.pdf). See page 4 of this document for the comparison.

Anyway, the AHJ does have the final say, but it is the engineer that will design the system and calculate the design wind pressures. Your home may need to be evaluated to ensure the structure is adequate. If you have signed and sealed engineering documentation that shows 4' spacing, the AHJ will accept it and you can proceed with an attachment spacing that is based on reason and reality.

As for the number of penetrations... It should not really matter from a risk perspective. If it's done right, the number of holes is rather irrelevant. Get someone who knows what they are doing, and you'll be fine. More penetrations means more distribution of the load. There is definitely a risk/cost/performance tradeoff, but the minimum requirements are perfectly adequate in my experience from a performance standpoint, and the cost is reduced significantly. Some may disagree, but is will always boil down to a tradeoff.

A good, experienced solar contractor should be able to provide a second opinion. I don't make it up that far, but look me up in my profile and I might be able to help you find a dealer that can help.

Jason Szumlanski

Edit: You may require 2' spacing in Zone 3, which would be more significant on a gable roof, but that would still only affect the edges of your array.