flashing a deck ledger on a foundation
On my upcoming deck job the 22’ledger is going to be bolted to the foundation wall. I had planned on using SS washers as spacers so I didn’t have to flash the ledger to house connection and then just use 90# felt over the top of the ledger and joists. The BI for the town (I don’t normally work in this little town) nixed that idea and said that he would like to see no space and a flashed connection. I think I am going to slot the wall above the ledger and install copper flashing like I would if it were a brick wall. Is this correct? Is there a better way? Should I try to convince the BI to let me use the spacer method like I have always done in my town? P.S. I hate caulk for anything involving a deck so any method using it is a no go.
Thanks,
Day
I am not an expert, just a know-it-all.
Replies
Assuming copper flashing and a concrete foundation, the copper will melt away fairly soon so I'd use galv.
I'd space the ledger off the wall, for air circulation, and flash the top of it, to keep twigs and leaves outta there. Over time, if it fills with crud, that space behind the ledger will probably become permanently wet.
I wonder if Simpson has anything for anchoring a ledger to a concrete wall.
What is the foundation made of? Can you get behind the attachment points? ie - is it to be through bolted or lagged? Very heavy vinyl flashing is gaining popularity in my part of the country. Copper is used too.
Personally, I think galvanized is not a great choice since, no flashing, that I have seen is hot dipped - which is what is recommended with ACQ PT lumber.
Re caulk, I share your feeling but... - using polyurethane or similar in the bolt holes through the foundation is not a bad thing... Also, if you 'let in' the flashing like I think your are suggesting, I think I'd want to goo it up with something...
Good point, the ledger would have to be flashed with Vycor first and then galv if it's ACQ.
There is an article on bolting ledgers to a house that appeared in JLC the past few years. The engineer who researched the article also gave a presentation at a JLC conference in Chicago last Sertember, which I attended. He nixed any connection that used washers as spacers. He said that that space could cause the bolts to shear off.
I like to take snow and ice guard and line the backside of the rim against the house. I leave enough to hang above the top of the rim by about 3" and fold it down on top of the joist then nail off a piece of flashing to hold it in place. The flashing on a concrete foundation would go on with the leg running downward on the backside of the rim. Drill holes and use redheads to anchor. Once the rim is in place, I'll take Lexel and run a serious bead down the line between the flashing and the concrete. I'm not sure you get a good enough joint between flashing and house when you score the concrete since it's so tough to make sure it's seated into the slot the entire run of the rim. By running the snow and ice guard long, it sheds water out past the joint between the rim and the joists and isolates the flashing on the underside. A strip of 30# felt can isolate the top side of the flashing from the decking (if you're using ACQ decking) to prolong its lifespan.
That's interesting. I've always wanted to try spacing the ledger with washers. How is the washer, with no weight on top of it, going to shere? I would think the ledger would make it shere first.
I think it is the bolt rather than the washer that will shear. The washers act as a spacer between the ledger and foundation but the bolt is not snug up to the foundation. The washers provide a space where the wieght of the deck can concentrate and that bolt and shear it off.
I'm sorry. I understand that it is the bolt that would shear. What I don't get is, the weight on the ledger is always on the bolt, regardless of the spacer. there is no direct weight or down pressure on the washer itself.So, my thinking is, and I could easily be mistaken, that the washer makes no difference. The bolt could shear with or without the washer.I haven't tried this system yet, so you could be right, and I would hate to find out the hard way.'Going down?'
I cut ABS pipe into short spacers, then lag or through bolt through the spacer like you would a washer. I guess you could apply a bead of caulk on each face of the spacer, but I've never done that.
You guys that are talking about the flashing touching ACQ. You "L" flash above the top board of the deck and behind the siding, don't you? How would the flashing ever come into contact with the ACQ joist?