Our 20 year old tongue and groove hardwood (veranda covered) timber deck was/is showing minor signs of rotting on the end grain of the timbers. I have filled and painted 100mm of the end of the boards which seems satisfactory for light rain. Unfortunately the decking has been laid the wrong way with the end grain of the planks exposed to the weather. The timber has shrunk, the previous tight tongue and groove joints have opened up and during windy rainy exposures the rain can wet up to 1 metre of the wood and then drain back into the channels between the planks and deteriorate from behind the water based filler that I have used. Maybe a deck sand followed by multiple coats of a marine grade epoxy to fill up and seal the gaps between the boards?
