Posted this already over at alt.home.repair, which so far has spawned an
absolutely fascinating discussion of a collapsed deck, but no useful
answers, so here's the deal:
I've got a house with vertical board and batten siding. I want to build a
deck, so I need to hang a ledger board. The only issue is the flashing.
With normal siding, there's an obvious place to put the top edge of the
flashing - it goes under the siding. But, with vertical siding, I haven't a
clue where to put it - do I fire up the circular saw and run a kerf across
the siding, and put the flashing into that? It seems somewhat
counterintuitive to do this, but I don't see any other way to do it.
I've also been considering anchoring the ledger board somewhat off the
siding by using several of those "giant fender washer" type things. I'd
guess that this would give the water somewhere to go rather than staying
between the ledger board and the siding, and would prevent rot.
Isn't the idea of flashing to separate the house from the deck? When
I have built decks (a few so far, and more to go), I have attached the
ledger board to the hourse with the siding in place with lag bolts. I
then placed the flashing on top of the ledger board and siding so that
the first course of deck boards cam in contact only with the flashing
and not the wood. this gave me the separation fo wood to earth and
wood to house that is needed.
Am I missing something in the OP?
Both of these show horizontal siding, and the top edge of the flashing goes
under the siding. The question is, if I have nothing to insert the top edge
of the flashing under, what do I do with that top edge?
I've had similar impressions in my visits to alt.home.repair.
The thought about standing off from the siding has my vote, but I think
I'd go further than a few fender washers. Maybe a couple of spacers
made of pressure treated materials, in 2x thickness. With the lag bolts
sealed with a good silicone caulk, or similar, you should be able to
keep the water out. "This Old House" did a short bit on this a while
back, but it's in the subscriber section of their website, and I'm not
going to do that again. thank you.
This may be a good time to talk to the building permit & inspection
people at the planning stages. (Stated at the risk of firing up those
who believe that these folks are the enemy.) I'd rather have a permit
and inspection, should I need to deal with my insurance company later
for some reason.
I don't see kerfing the siding.
issue is the flashing. . . with vertical siding, I haven't a
Just cutting a kerf will defeat the purpose of the flashing, and using
fender washers is no guarantee you won't get rot behind the washers
(though I've seen it and done it myself).
If it were me, I'd go to the trouble of cutting away the siding (board
and batten), exposing the sheathing, to the depth of the ledger plus a
1/4", flashing the joint, and hanging a double ledger (or spacing the
single ledger out from the wall with blocks) so you've room to attach
the decking. Before flashing the joint I'd also use a good quality
primer on the cut ends of the siding (to keep the water out), and make
sure there was building paper tucked into the gap as well.
Be sure to use through-bolts (if you can reach the back side of the rim
joist) or long enough lag screws--don't just nail the ledger: most
deck collapses are caused by improper attachment (you probably already
know this, but I can't tell you how many decks I see nailed to the
sides of houses--it always looks like a law suit to me). Good luck.
Amen to that - that's one of the many reasons this deck is coming down. The
ledger board is simply screwed on with a bunch of what appears to be drywall
screws. As near as I can tell, there is only minimal if any penetration
into the framing of the house.
Amazingly, this arrangement has withstood some pretty serious snow loading -
the steel roof insures that there's generally two to three feet of
hard-packed snow on the thing. I keep waiting for the whole thing to come
down, saving me the trouble of demolition, but alas, it has not. Go figure.
A few options...
1. Remove the battens, tack up a temporary straight edge, and use use
circular saw to cut a kerf in the siding that you can slip the top of the
flashing into. The kerf should be cut at a 45 degree angle so that any
water that finds it's way into the kerf will drain back out and not into
the wall. Reapply the battens after the deck is finished.
2. Space the ledger board away from the wall using a stack of washers.
Bolts w/nuts would be best if you have access to the back side of the rim
joist (crawlspace or basement), but installation would be difficult and
definitely a two person job. Lag bolts would work almost as well, and are
much easier to install.
3. Add extra footings/posts and eliminate the ledger board entirely. Make
the deck self supporting so that no part of it actually touches the house.
Given a choice, I prefer to keep the deck isolated from the house (#3).
Otherwise I would probably go with option #2.
My county requires option 3. Decks are not permitted to be hung from a
ledger board. They must be self supporting. That means that several
people could, if they worked at it, possibly get the deck moving enough
to bang it into the house, but the 3/8 inch gap has been enough so far.
Free standing does eliminate the concern about how to flash the ledger.
Michael and MJ Houghton | Herveus d'Ormonde and Megan O'Donnelly
firstname.lastname@example.org | White Wolf and the Phoenix
I've done several similar decks & was just on one I did 15 years ago.
All was fine. It's a cedar deck, but the ledger & rest of the joists
are CCA treated. You never see the difference after a year or so since
the structural boards aren't very obvious nor is the color that
different with some aging.
There isn't a need for flashing at all if you use treated or other
weather resistant wood, IMO. You have to cut or pull the battens, but
put the ledger flat against the house. Just run some caulk over the
bolt holes in an eyebrow shape, don't caulk anything else. You can also
put a slight bevel on the top of the board so it pitches away from the
house. I generally just use a hand power planer as if I was doing the
lock side of a door (3 degrees).
I also wouldn't stand the ledger board off from the wall at all. Any
space in there is just going to be a great place for bugs to hide &
debris to accumulate. Then it will get wet & promote rot.
I prefer just to cut the battens, myself. Pulling existing battens is
often just asking for trouble. They wind up breaking, cracking or not
going back as tight.
The deck should slope away from the house about 1" in 4' & that's
plenty to keep the water off if you don't let crap pile against the
wall. Snow should be removed & not just left up against the house,
My experience is with north central Maryland, so YMMV.
Treated lumber will prevent the deck from rotting, but it won't protect the
Any water that works it's way down between the ledger board and the house
siding is potentially a place for rot to start. If you have a good roof
overhang and caulk along the top, it probably won't see enough water to
matter. But, if this were on a wall fully exposed to rain, I sure wouldn't
want to risk it.
I've seen plenty of rot behind simple horizontal trim boards on a house,
and that's with an annual check of the caulking. Once a deck is installed,
you'll probably never look at the ledger again, or even have access to
recaulk it when needed.
I would still vote for a self supporting structure, not attached to the
house at all.
That seems rather steep to me? The plumbing in my house uses that pitch.
Unless you are using T&G decking, most of the water will fall through the
gaps between boards anyway. And, a slope would be useless if the decking
runs parallel to the house.
If it doesn't need to be attached, don't attach it. Low decks seldom need to
It is not so steep when you are standing on it. Draining concrete usually
requires about the same slope. But I agree for a deck you could probably get
away with less. You could even go to 0 if you like. Depends on the climate
and exposure to sun. It is always going to be wet when it is raining, so
your goal is merely to make sure it dries fairly quickly when the rain
stops. That means no puddles. Laying the deck so that the boards cup
downwards is a bigger factor than slope.
True. In the case of T&G you definitely want to slope the deck.
I disagree with caulking the top of a ledger board because it can't be
maintained & never sticks, in my experience. I think it holds more
moisture than if left uncaulked. Depending on how it's done, the type
of siding, etc... it's certainly an arguable point.
I've seen rot behind a lot of trim, too. It happens. I've rarely done
self-supporting decks because the cost is usually more than the home
owner is willing to pay and usually aren't worth it - you certainly
won't find many in this area. Code & custom vary widely, though.
The slope may seem steep to you. I know some that do it 1" in 6', but
it's about standard. I've never had a complaint about it & it does
keep water from laying against the house pretty well. Our weather is
full of snows that melt & freeze. Those are the most dangerous for
getting moisture into the house, I've found. The snow holds the melt
against the house so it can work its way up & in some pretty odd
places. Best to keep it off, but most homeowners don't seem to do that
sort of maintenance. Lazy.
Against the house, any openings in the deck are often clogged with
debris after a year or two. Dirt, leaves, dog hair & everything else.
It's one of the reasons a lot of contractors I know put more of a slope
on the ledger board. I think a few degrees is plenty, so long as the
board is plumb, which it isn't always. I'll never shim out the top
At any rate, all of the above is just my opinion for my area. I've
done a fair few decks in the mid atlantic states & know a lot of the
people in other ways, so I'd hear about issues. I will admit that
there aren't too many decks against wooden siding, though. Maybe a
half dozen total in 30 years. Usually it's vinyl or block which
simplifies life a lot. I wouldn't put wooden siding on my house. I
don't want the hassle of maintaining it or the other problems it
I didn't mean to suggest caulking as a reliable option. But, if the ledger
was bolted directly to wood siding without appropriate flashing, caulking
seems like the only real defense. Otherwise, I would expect rot between the
ledger and siding.
Our old decks were for a mobile home. I knew the mobile would eventually
need to be moved, and didn't want to make any permanent attachments to it.
I also didn't want to risk any rot behind a ledger board. Ironically, the
entire perimeter of the mobile siding rotted out behind the lower
horizontal trim. That was a whole other issue to have to deal with... :)
When we built our new house, I designed the front deck to be separated from
the house siding as well. It shares a concrete foundation with the house,
but the deck structure has no contact with any part of the house. It
probably cost more to do it this way, but I think its the best long term
I personally leave a 1/2" to 3/4" gap between the deck and house siding.
It's small enough to keep most objects from falling through, but large
enough that it doesn't clog with debris. We can get some deep snows around
here, and any snow that might melt against the house can drain off below
the deck easily.
In that case, I wouldn't hesitate to bolt a pressure treated ledger against
vinyl or concrete block. In the long term, the deck ledger may eventually
rot out, but the deck will probably need replaced by then anyway... At
least it wouldn't take the house structure with it...
Anthony, I do agree that your method is best for any wood siding. For a
mobile home, it's absolutely the only solution I'd want to use. Mobile
homes are a different kettle of fish entirely. Mostly, the decks I've
done have gone up against western red cedar siding & I haven't seen a
problem. Of course, we always try to make sure there's a good coat of
whatever finish they use on it before attaching the ledger board. I'll
assume that when they reapply, they powerwash the garbage out first &
let it soak back there as best they can. Can't say that with any
certainty, though. Haven't heard any complaints though.
In any case, it isn't perfect, but I've rarely seen anyone who wants to
pay to do things completely right. It's generally a compromise between
cost & 'right'. Sometimes that's on our part, depending on how the
price was arrived at. A lot of times on decks you're competing against
what the home owner thinks he can do it for with a case of beer & a
couple of buddies or some handyman who doesn't even have a license or
insurance. In that case, you have to decide whether to bother doing
any pricing at all. Most people think they know what they want, but
they really don't know the details & don't want to know. They think
with their wallets.
Other times they think with time. You can't believe how many calls we
used to get to do a deck before a big party. Then people are willing
to pay & you can squeeze it in, but don't have time for all the bells &
whistles. There's usually something. A perfect world, it isn't.
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