Redesigning a Deck Over an Existing Room (version 2.2)
Much like that scene from Monty Python and the Holy Grail, where ‘King of Swamp Castle’ built several castles because they kept sinking… we built several decks because they kept leaking. But the third deck, that one stayed up and stopped leaking!
The original deck was laid on top of an existing room, however we quickly noticed with the swift weather changes of the PNW, that this room was leaking from the above deck structure. No bueno!!
This was something we had to address quick so we came up with an idea to engineer the deck to be removable in panels about 3’x 3’. Using cedar due to its natural qualities to repel rot and better withstand the weather we have here.
However, with our lack of experience and knowledge of water intrusion into homes, we built this deck still sitting directly on the surface of the roof structure. That we found prevented airflow to help dry out the undersides but also prevented water from flowing off the surface very well, so leaking ultimately became an issue a year after the rebuild and we came back to the drawing board.
The next deck (v2.2), we tore up the entire rotting roof, sloped it to allow water to flow to one side which would be caught in a gutter and directed away from the house. While also installing a complete new water barrier membrane to the roof surface and then engineering the deck to be elevated at least 4-6” off the roof allowing good airflow underneath, ease of access still if we need, and ultimately water flow off of the roof.
7 years later, and it is still holding strong, no leaks and the only real maintenance has been protecting the cedar. The wood is now nearing 10 years and because life gets busy, I haven’t kept up with treating it every other year as I’d like and I can see, the elements are starting to take its toll.
But when we are ready to do this again, the only change at this point would be to use Trex or recycled plastic planks due to their ease of maintenance. It will be more costly up front, but it will last us way longer without the continuous hassle of treating this 20’x20’ deck every year or two.
