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Home My WebLink AboutCOM 0838.005 2010-2012 8083294786 COUNTY COUNCIL KONA COUNTY COUNCIL KONA 09:46:59 a . 10-02-2012 2/4 ��NCE HEr � yF'pi LICENSED T pROFES510NAt_ -p 10/1/2012 O ARCHITECT * NO. 14938 HETHERINGTON ARCHITECTURE LLC y Q: • John L.Hetherington,Architect,AIA Member,Hawaii lic.#AR 14938 9/4,q/1 73-4428 Mamalahoa Hwy. Kailua Kona,HI 96740 808-938-3498 hetharch@gmail.com 3 To:Chairman,Dominic Yagong,Hawaii County Council COMMENTS REGARDING BILL 305 L N Aloha All, Since it became required under Section 1,Chapter 9,Article 5....for all Solar Photovoltaic projects to bear the seal of an architect or structural engineer,I have reviewed 26 different residential solar photovoltaic projects. The architectural and engineering concerns are primarily related to water-proofing,structural integrity. While in some cases the structural concern is minor; According to the 2006 IBC,adopted by the County of Hawaii: 2303.4.1.7 Alterations to<<trusses>>. <<Truss>>members and components shall not be cut,notched,drilled,spliced or otherwise altered in any way without written concurrence and approval of a registered design professional.Alterations resulting in the addition of loads to any member(e.g.,HVAC equipment,water heater)shall not be permitted without verification that the<<truss>>is capable of supporting such additional loading. The county apparently per administrative ruling has waived the structural review for single story truss roofs. According to a bulletin issued by MiTek,(The connection engineering behind the pre- fabricated trusses built here on the Island)Trusses should not be drilled without serious review of the structural consequences and preferably not at all. (see attached bulletin "Proper Loading for Solar Panels) Many of the older homes here on the Big Island were built before building codes were established. In four of the projects I have reviewed so far there were serious structural concerns about not only the added load of a solar photovoltaic system but the live load of workers on the roof. I have designed structural retrofits to allow the owners to add the desired system safely and in several instances insisted that a ground mount system be used due to the expense of making the roof structure safe enough to support the additional loads. Comm. No. • 3 0•C Ref. To: _i_.• i Ref. Dole QCT 9 3 2012 8083294786 COUNTY COUNCIL KONA COUNTY COUNCIL KONA 09:47:33 a.m. 10-02-2012 3/4 I have personally seen 1x6 rafters spanning 10 feet or more,4x12 rafters @ four feet on center spanning over 20 feet,lanai roofs with 2x4 rafters spanning 8 feet,trusses spaced 4 feet on center with insufficient 2x4 purlins to support additional loads.In none of these cases would the existing structure safely support the additional loads imposed by a photovoltaic system and could have caused accidents for the workers installing the systems. I believe that for the public safety and welfare,all photovoltaic projects should be reviewed by a structural engineer or architect licensed in the State of Hawaii. These are very small projects and do not generate a great deal of income for the engineers and architects reviewing and certifying the projects.Its not about the money...its about doing what's right. Thank you for listening Aloha Nor John L.Hethe gton 8083294786 COUNTY COUNCIL KONA COUNTY COUNCIL KONA 09:47:51 a.m. 10-02-2012 4/4 , Proper Loading for Solar Panels As the"Green"movement progresses and energy prices go increasingly higher,more and more • homeowners and commercial developers are looking to utilize photovoltaic panels(solar panels)to help get them"off the grid." It may seem that designing for solar panels is as easy as finding out how much the panels weigh,and adding point loads to their roof trusses either in the design phase,or in a repair. Unfortunately,it is not always this simple. Some applications of solar panels do lay flat on the top chord of supporting trusses and thus,create a uniform load and not point loads,however this simple case is not the subject of this article. Typically,a key selling point that a solar panel installer has is that he/she can minimize roof penetrations, thus reducing the possibility of roof leaks. While this may help reduce the likelihood of leaks,it can often create large point loads on the supporting trusses. Before explaining some of the Intricacies of how solar panels interact with roof trusses,you should be aware that if you are sending a repair or seal to MiTek that is the result of the installation of solar panels, your engineer at MiTek will ask that an independent engineer or qualified persons specify the loading for the panels. It is up to the independent engineer or qualified designer to determine if the resultant loads shall be considered as point loads or uniform loads,as well as the magnitude of those loads. In residential applications,one typically has a pitched roof in which solar panels are mounted parallel to the roof pitch. If the roof has a low slope,the gravity loads of the solar panels can be magnified as the solar panel may hold snow,thus causing point loads from snow rather than a uniform load. The same holds true for wind loading as the wind uplift is accumulated through the solar array and directed to the posts that support the solar panel. Also,depending on the roof geometry,the solar panel may act as a sail and catch wind from under the panel thus creating very high uplift loads. In many commercial applications,solar panels are put on flat roofs. In order to achieve higher efficiency,the photovoltaic panels will be posted to the roof such that the panels are at a pitch that will be angled toward the sun. With this geometry,snow can accumulate on the solar array,but can also slide off of the panel thus creating a drift on the low side of the panel. Also,wind can create many different loading scenarios. Yet another concern that can come into play is that solar panels are often attached to trusses with lag screws that must land in the center of a L5"wide top chord. Depending on the diameter of the connector,a repair may be required due to the section loss of the wood In the top chord. MiTek recommends that all connections of solar panels be made into blocking that is run between trusses. This not only prevents the drilling of trusses,but also distributes any point loads between two trusses,thus decreasing the severity of any repairs. All in all,the design and/or repair of roof trusses while adding solar panels is not something that is to be taken lightly. There are a lot of loading scenarios that should be examined. As always,if you have any questions about the topics covered in this article,give your MiTek engineer a call and he/she will be glad to help you out; 8083294786 COUNTY COUNCIL KONA COUNTY COUNCIL KONA 09:46:37 a . 10-02-2012 1/4 FROM:Kona Council Office Phone vm..X201 Fax V2.cf-1}}667 FAX3 To: Lau{'q MWV ashlgeI From: L1411 gobihsOn Fax: att1-qt11Z Pages: 4 (,IY1dudiug*is coyefr- ,9G) Phone: °1 CO 1-S�Ity Date: 10-02-12 I *.? 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