If there is one critical area of any house project which can go oh so wrong in so many ways — it is the roofing. The ubiquitous Thai construction crew is fairly skilled in many aspects of construction, but one common shortcoming is in roof construction. As it turned out here, the roof valleys were done totally inadequately. If you think about it, roof valleys would often not come up in up-country construction, where houses commonly have no roof valleys. In future projects (if I knew then what I know now), I would definitely farm out the roofing to a company which specialized in them.
Anyway, on to the repair. The company which came in to do the fixes was known by me as I had watched them do the roof valleys on a neighboring project. At the time I thought, yes that looks about how it should be done. Although this company does do entire house projects, they also specialize and also do individual roof jobs.
There basic technique is this: They use a 1 meter wide piece of flat thick galvanized, which they score down the middle with a two by four making the piece into a v-angle which will sit in the valley.
They then set the galvanized on top of the roof metal and ribbing. The tiles are tabbed so that they normally fit in place on top of the ribbing and on top of each other. To secure the lower tiles in place they cut the tabs off the tiles and secure them in place with wire from the ribbing above.
I will report back during the next heavy rain! Update: Yes! It is totally dry up in the attic during a heavy rain. (This house is located in Pattaya, Thailand)