t1-11 z-flashing and water

ben · 2009-07-08T20:57:30+00:00

I'm working on a project to replace the bottom 20" of t1-11 typesiding on my house. I cut and stained new 20" sheets (including edgestaining). I cut off the bottom 20" of siding from the house. Istained the new cut edge. I slipped z-flashing under that new cutedge and nailed it in place through the siding about 1 3/4" above thecut edge (the back edge of the flashing is 2" tall). I left a 1/8"gap between the new cut edge and the flashing (so that panels areseparated by 1/8"). And finally I slipped the new panels into placeand nailed them in with galvanized ring shank 8d framing nails.I finished this yesterday on a wall and then we had a massivelytorrential rain last night. Today I went and looked at it (this is awall in the garage so I can see the other side of the wall too).There is dampness on the back edge of the siding just above the backedge of the z-flashing. Not everywhere but in some places. Backoutside I looked at the flashing and you can see some water stillsitting in the groove.Is this normal? One thing that is true is that the existing siding is*badly* in need of new stain, so it could be wicking in above the newcut edge which I stained. But it seems most logical to me that wateris sitting on the flashing and wicking up into the wood.The flashing profile is 90 degree angles. It seems like it should bea little less so that water is encouraged to run out. I can try andbend it a little bit on subsequent walls.Needless to say I'm disappointed. I guess one question is whether theflashing is supposed to keep the water out completely or simplyprovide an avenue for it to get out and evaporate?thx

Jul 08, 2009 21 Replies

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Indeed. I started on the back wall of the garage figuring I'd work out all the kinks there. What I didn't think about is that it has a bit of a roof overhang and so the wall doesn't get near as much water in a rainstorm. So I didn't catch the problem until the second wall.

I'm sure you're right about most people just not knowing the problem they're creating. The 8' horizontal joints on my house are all 0" gap between flashing and siding, and the siding is buckled out in some places as a result.

Cabot, it's nice to hear that even you have some LOL moments like that. Your work looks fabulous.