Roof Attachments  Most solar power systems are installed on roofs. Although this technique is usually reliable and inconspicuous, leaks can occur over the lifetime of the system -- even under the best of circumstances. To minimize the possibility of leakage, we will not install a solar energy system on a roof that is old or is already leaking. Moreover, we have developed a variety of preferred roofing techniques that are suitable for a variety of different roof materials. Unlike solar hot water systems which are quite heavy and stable on a roof, solar energy modules are light and subject to substantial wind loading. Therefore, our biggest concern is ensuring that the roof attachment does not fatigue or weaken as a result of wind loading over its lifespan. Attaching mounting points to the underlying sheathing (instead of rafters) or through a brittle roof material is unlikely to resist water penetration over the lifespan of the rest of the roof. Here is an overview of the practices we use to provide the best long-term value for your solar power system. Composition Roof - Since composition shingles are flexible and compressible, attachment through the shingle itself is effective. Aluminum angles are securely attached to the underlying rafters with stainless steel lag screws. This assembly is then sealed using a urethane caulking material. Wood Shake Roof - Wood shakes can crack and leak if they are drilled or compressed. We therefore remove several shakes to locate the underlying rafters. Metal standoffs are then installed to these rafters with stainless steel lag screws. The standoffs are then sealed and flashed using a urethane caulking material. Shakes are replaced around the standoffs. Masonry or Rigid Tile Roof - Masonry shakes can crack and leak if they are drilled or compressed. We therefore remove several shingles to locate the underlying rafters. Metal standoffs are then installed to these rafters with stainless steel lag screws. The standoffs are then sealed and flashed using a urethane caulking material. Shingles are replaced around the standoffs.  Flat Roof - Since water can pool on flat roofs it is particularly important that the roof be in good condition. For these installations, aluminum angles are securely attached to the underlying rafters with stainless steel lag screws. This assembly is then sealed using a durable caulking material. If there is any possibility of water pooling around the roof attachments, it may be necessary to anchor the attachment points to wooden "sleepers" which are mounted above the roof surface.