What is the new Florida Wind Load Code?

In January of 2001, Florida adopted a new wind load code that specifies the design load psf that is required for installing solar pool heating systems in various zones throughout the State of Florida. (Individual building departments have until June of 2003 to implement the new code). If you are in a coastal zone, the required wind load psf is greater than if you are in an interior zone. (See Figure 1). As time goes on, this new code is being enforced more and more in building departments. In order to meet the required design load psf rating three items are impacted:

1. Restrictions on where panels can be located on roofs.
   To fulfill the psf requirement, collectors can only be installed in certain areas on a given roof. From Figure 2 you can see that the allowed area for monolithic collectors is much smaller than the allowed area for Heliocol collectors. For roofs with a 10 degree pitch or more, the restricted area where panels can not be located is calculated as 10% of the smallest width of the structure. As shown in the example where the dimensions of the roof are 30’ x 60’, this zone is 3’ wide, leaving only 9’ for panels.
2. Strapping requirements
   The tables below show how many hold down straps are required for monolithic collectors. As an example, in 130-139 MPH areas, design load is 45.4 psf which results in a max strap spacing of no more than 21”. That’s 6 straps on a 12’ collector. Heliocol systems on the other hand, require no hold down straps.
   
   

   ASCE 7-98
   Wind Velocity – MPH	100	110	120	130	140	142	146	155
   Design Load psf	23.2	28	33.3	39.1	45.4	46.7	49.4	55.6
   Panels not to be installed in restricted area.						Broward	Dade	Monroe

   
   
   

   Max. Strap Spacing
   Design Load psf	Spacing inches
   30	24
   40	24
   50	21
   60	17

   
   
3. Roof penetration requirements
   If it is not possible to penetrate the roof into the roof truss, all lag bolts must lag into a 2x4 block at least 6” long located directly under the roof sheathing. (See Figure 3). Think back up to the example above where 6 straps are required on a 4’x12’ panel. (According to the new wind code, there are (12) lag bolts per strap for five panels). Only one spot along this strap can be located on a 24” truss since the panel headers are not 48” on center. This equates to having to put up at least (40) 2x4 blocks in the attic for only five 4’x12’ monolithic panels installed in a 130-139 MPH wind zone. Sometimes there is simply no attic crawl space whatsoever. In comparison, Heliocol’s mounting system can always be located over a truss and do not require attic access.