Tough flashing problem...

gaaslaj · 11-20-2006, 11:39 PM

I bought a house that was build in the 70's. It has T-1-11 siding, it is a two story. There is a small cantilevered deck on the second story. The problem is that the builder did not put a flashing in bewteen the bottom of the 2nd story siding, and where the decks contacts the house. The upper deck joists actually go inside the house. It was caulked along the botton of the siding and the top of the deck boards but I've found that water still leaks down behind the lower siding. I'm considering nailing an L flashing along the bottom of the 2nd story siding, and have it extend over the deck boards to keep the water from getting down behind the top of the the first story siding. I would need to use a lot of caulk to fill the grooves of the siding. I would love to have somne ideas about how to do this in a better way. Thanks! John.

glennjanie · 11-21-2006, 10:27 AM

Welcome to the Forum Gaaslaj:
I would loosen the bottom of the 2nd story sheets and run a flashing 2" up under it. I would then make the flashing to come out between the upper and lower sheets and extend 2" down the lower sheets with a 1/4", 15 degree "kick out" at the bottom. I would come nearer calling this a Z flashing. This will eliminate the need for caulk between the sheets. Laps in the flashing should be 4".
The deck joists penetrating the siding is a serious problem. I would caulk all the way around each joist at the point of entry with silicone and use foam rods to back the caulking wherever it is needed. The joists could also be painted to prevent moisture penetration (Kilz 2 latex primer and 2 coats of latex paint and keep an eye on it for additional coats).
Glenn

gaaslaj · 11-21-2006, 12:46 PM

Thanks Glenn. The bottom of the 2nd floor siding sits on top of the deck joists that enter the house. There is blocking between the joists. Below the blocking is where the 1st story siding starts. It would be difficult to slip flashing under the siding and have it go down, the joists would be in the way. Would a drawing help? Thanks, John.

gaaslaj · 11-21-2006, 02:26 PM

glennjanie · 11-21-2006, 04:06 PM

I can see what you are talking about now. An "L" flashing would be good in this case, but I would caulk across the deck first.
I would not try to caulk all the spaces in the deck, as you apperantly have done. The deck boards need to breathe; it looks like you have a water-seal on them but they need to dry as soon as the rain quits.
Glenn

gaaslaj · 11-21-2006, 04:17 PM

Hi Glenn. I just caulked that first space between deck boards, and only for about 15 feet. What I may do is remove the deck board closest to the house, and then pry the bottom of the siding out a bit. I could then insert an L flashing behind the siding. I could put a 1/4 inch downward bend on the other arm of the flashing. I could make a small notch in the joist, and insert the bent portion of the flashing into that. This would be to stop water from running along the top of the joist into the house. What do you think? Thanks, John.