In an earlier article we looked at elastomeric roof coatings like Kool Seal to perform some preventative maintenance and to seal small pin holes on shipping container roofs. In addition, the light color roof coatings also reduce the heat island effect and the heat buildup on the inside of your container often caused by a darker painted or rusted container roof. With its main purpose being to keep the elements out, shipping container roofs are the weak link in the whole structure. Shipping container walls are constructed from heavy-duty 14 gauge weathering steel and the posts are fabricated from 7 gauge tube steel but the roof of shipping containers is constructed with 16 to 18 gauge die-stamp corrugated steel sheets. These roofs have very limited load bearing capacity, any loading on containers is meant to be distributed to the ground (or boat deck) by the four corner posts, not the roof.
Often shipping containers may get a dented roof due to handling while being loaded or unloaded from cargo ships. Should the containers roof get a dent in it where water can puddle it should be repaired before it rusts through. If you do find that you have water entering the container, the best fix is to remove the damaged portion of the roof and weld in a new steel roof panel section, however in some situations this is easier said than done. If the if the proper tools and equipment are not available then you need an alternate but permanent repair.
In the modular building industry we have had a great deal of success using a product called EternaBond to permanently seal the roof seams between building sections. EternaBond works on both metal and EPDM surfaces and it is used over and over again to join the roof seams on rented modular buildings. Modular buildings are delivered, set up, and used in sometimes caustic environments like chemical plants for several years. When the rental is over the roof seam is cut, the building modules pulled apart then sent to a new site where another slightly wider layer of EternaBond tape is installed right over the top of the old tape seam because the preceding layer is to difficult and time-consuming to remove. As the roofs aged and deteriorated with several layers of abandoned seam material a new EternaBond tape layer rarely failed us.
EternaBond is a rubber tape product with adhesive on one side. To install it you clean the surface, brush a primer product on the surface, apply an adhesive to the surface then press on the EternaBoond tape. You will immediately have a long-lasting water tight roof patch. For added protection you can apply an EtrnaBond chalk to the edges of the patch. EternaBond is available in 50′ rolls starting at 2″ wide going up to 48″ wide so you can find an EternaBond product for almost any container roof patching need, both emergency and permanent.