Roof Deck Leaking Into Garage Underneath

homemade asks,

We have a flat 12×12 deck off our master bedroom. It sits on top of our garage. We love it and want to keep it, but it continuously leaks water into the garage below. We've tried everything we can think of, from rebuilding the deck with outdoor tile to adding more drains (when snow melts, the gutters can't seem to support all of the water. We make sure they're always free of leaves, but they still overflow). We're getting to the point where we might just give up. We don't have a large budget for repair, but we're thinking about enclosing the deck completely, or covering it in glass and turning it into a sunroom just to put this leak problem behind us. What are your thoughts? Would this affect the value of our home?

Our Answer

A master bedroom deck adds significant value to a home, and, if well maintained, is also an attractive selling point. That said, decking is one of the most difficult surfaces to make watertight.
I suggest taking all reasonable strides toward fixing this problem, and I think your best option is to install a fiberglass deck. Fiberglass decks are installed by forming fiberglass on top of the old roof surface once those garage roof leaks are repaired. The fiberglass goes up under the siding and becomes an impervious surface – that is, no water can get beneath it.
Before installing it, contractors will make your roof as flat and smooth as possible, and will also add a little bit of pitch. Then, they make the fiberglass, lay it, cover it with resin, add more fiberglass, more resin and so on – similar to how you'd make a boat hull. The upper layers have an abrasive sand in the epoxy, giving you some surface resistance. The whole thing is formed in one continuous piece. This is your best bet for maintaining your deck while also bringing an end to those troubling garage leaks.