It is amazing how many times I find water damage hidden behind rim joist insulation. Looking at the photos, you can see previous repair attempts, including a pound of caulking! Certainly recommend close inspection of joist bays if accessable. Especially below doors and at deck ledger boards.
Beautiful maintenance free deck built with the house in '02 using a trex or similar product. House is virtually unlived in, built by an older couple. The deck “boards” swelled up, and didnt allow drainage, which around here means with rain/snow/freeze/thaw = large piles of snow and ice on the deck, and tremendous weight added. The deck now pools water, about 1/4 inch. Had it been built poorly, it would be worse, but it is built with 2x10’s, with more than adequate support, just not enough to handle the thousands of pounds of snow times many winters. This backed up water against the house, and it found a way in. This is near the middle of the deck, and my guess is this is where the flashing is lapped, it was only showing moisture damage here, not the whole length. This is the Eave end of the house, with no gutters above it, so between the square footage of the deck plus the roof, there has been lots of water pouring on the deck.
Good synopsis Mike. That explains it. That is why when I build a deck like that, I first cover the top of the ledger board with vycor flashing and then install the copper or plastic L flashing and then flash it again with a vycor flashing on the vertical wall with the WRB draped on top of that. Prooves good for that kind of water intrusions at the lap joints.
Wasn’t there a gap between the deck boards if this was composite decking?
That stuff will expand up to 1/2" in twenty feet and 1/8" width wise.
But when it is cold it shrinks, so you would think the gaps created would provide the proper drainage to prevent ice buildup.
Just a question I guess. I’m a fanatic when it comes to what caused it.
Thanks for your explanation. Good points to remember when we look at decks, and more reason to check inbetween the joist and band joist when accessible.
There have been a number of defective maintenance free decking that inst supposed to swell that did. I know one house that the decking was replaced free of charge because it held water. The Hot/cold does cause expansion/contraction, but the defective ones swelled due to moisture. Some if the plastic “boards” use wood fiber as a filler that eventually swelled.
Plastic L is not something I’ve used… Why plastic L Marcel? Copper I understand, I’m assuming the Plastic L wears better “up there” (by YOU) than does galvy? Forgive my ignorance :-), we’re much drier here than are you! I’ve used galvy and a config much like your own…or, minus the plastic L exactly like that.
The vycor, is that a self adhering or similar? I’m trying to remember the name of the butyl type I’ve use. Some of the self adhering types are my favorite in those areas as well to go over the flashing/L and be an intermediary between the metal and the draped over Moisture Barrier.