Just about everyone uses lag screws to attach ledger boards to the house.
This got me wondering as to how that is any stronger than attaching w/ 3 16d nails @ 16″ OC. Especially since the rim joist that they are being attached to is only fastened to the floor joists with 16d nails…
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It just occured to me that with the rim joist, you don't have to be as concerned with pull out since it is also toe nailed to the mudsill & the subfloor is also through nailed.
This wouldn't be the case with the ledger, so maybe I answered my own question since lag screws would be far less likely to pull out.
I used a combination of lag screws and through-bolts (where I could). But you refer to "pull out". Do you mean a force excerted at right angles to the house wall actually pulling the daeck away from the house? Why would that happen? It seems to me that the ledger fasteners just have to resist the shear force caused by the weight of half of the deck. But I want to hear what the pros say.
You are correct, I guess that wouldn't really occur - unless someone decided to tow the porch away ;)
That brings me back to why nails wouldn't be sufficient - after all, when you use joist hangers or ledger strips to support floors, it's just nails holding it up...
Someone pointed out to me a couple years ago on this very forum that when you are walking on the deck, away from the house, there is a horizontal force vector being applied with every step (think of your weight going forward and the friction between your foot and the deck). Over time this is significant, thus the requirement to offset it with lags.
But isn't the horizontal force vector TOWARD the house? As I walk forward, away from the house, I'm pushing the deck back toward the house. Ummm, but when I walk back toward the house, I'm pulling it away from the house? Are these forces really significant sources of strain on fasteners.
I think I'm safe -- I used lots of 16d nails to hold the ledger in place while I drilled for bolts and lags. I am also pleased to brag that I used two hole diameters for the lags.
I guess the horizontal force is forward when your foot lands, backwards when you push off with a step. May be small, may be in both directions, but in time could loosen up a nailed joint. It doesn't have to move far to fail catastrophically.
Nails will fail quicker than lags or carriage bolts under shear forces. Carriage bolts and lags also resist pull-out via either the threads on the lags or the nut/washer on a carriage bolt.
A combination of pull-out and shear forces are usually what causes decks to fail. The rim joist on a building is usually secured on five of six sides and is under compression which virtually locks it in place.
I've been using LedgerLok screws for ledger attachments lately. They are fantastic. Put a nut driver in a drill and zip them right in. No predrilling required. They are only about 1/4" thick and are stronger than a 1/2" lag screw. Not cheap to buy, but they earn they're keep by offsetting the labor involved. I think they are made by FastenMaster, but I may be wrong.
FWIW, most decks you see are under engineered at the critical ledger/house attachment point. Do a little research and you'll be surprised at how many lags or carriage bolts are actually required for a proper attachment. I usually end up with either two lags or two LedgerLok screws in every joist bay. Sometimes more. Using carriage bolts will reduce the number of required fasteners, but I usually find that they are a logistical nightmare to install.... especially on older homes.
Very rarely are lag screws even installed correctly. Proper installation requires two different size holes being drilled. A hole the size of the lag screw measured inside the threads or slightly smaller is drilled through both members. The ledger is then drilled out to the nominal size of the lag bolt. It is crucial that the threads properly engage the rim joist, but not the ledger board. Running them in without predrilling, drilling a continuous oversize hole, or drilling a continuous undersize hole can damage the wood fibers and greatly reduces the system's strength.
Don't rely on just nails.
Proper installation requires two different size holes being drilled ... measured inside the threads or slightly smaller .... The ledger is then drilled out to the nominal size of the lag bolt.
Hey, good information and I'll use it next time with lags.
I think I read it in FHB or JLC to be honest! I'm telling you though.... LedgerLok screws...... awesome. You won't believe how easily they zip in and every box comes with the engineering specs inside (and a nut driver too) to show the inspector when he raises an eyebrow. I've never had one strip, shear, or fail to run home during installation. And that includes running them into old construction as well as nice soft new. A great product that I'm sure is going to catch on when people figure out these things are out there. Did I mention no predrilling? ;)
Where do you buy your ledger loc bolts ? I know about them but when I look for them all I find are the landscaping timber bolts which I have snapped upon occasion.
Arrow, I've only found them at local lumber yards, but I know of two off hand that stock them regularly. I've only product I've seen at home centers are the ones for landscape timbers that you mentioned, and they are a much different animal strength wise. I'll be you could buy them on the web though and they're relatively lightweight so the shipping wouldn't kill you.
A few years ago I bought the header bolts that were similar, from the lumber yard I ordered my lumber package from. I think they got them from their supplier. I just would like to buy them at a moments notice and most yards don't seem to keep items like that in house.
Running them in without predrilling, drilling a continuous oversize hole, or drilling a continuous undersize hole can damage the wood fibers and greatly reduces the system's strength
I had to laugh when I thought back to my early years when I used to "predrill" the lagbolts with my 20 oz rocket!
Heck, I'd still do that today for my own stuff! Maybe not for a high deck....
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Remind me not to party on your deck.
Yeah I know..... "I've been doing it that way for years and they're all still standing". Right? Who knows... maybe you're right.
To be entirely fair and honest.... I've driven lags with a hammer too. But it was before I knew better.
code specs 5/8" BOLTS
Who's code? Not mine.
I wouldn't party on my decks! Actually, I wouldn't build a wood deck for myself. I've grown to hate them.
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My thinking is that the new fastener recommendations for decks (in the wake of all of these spectacular failure cases) has gotten absurd. Fastener every 6 inches? Come on now, where did common sense go?
It just seems more practical in many cases to build a self-supporting deck, and forget the ledger. Less chance of rot too.
Bolts are better than screws. If you read about deck failures, one of the chief causes is the wood shrinks AWAY from the threads of the carriage screw, and therefore, the screw loses bearing, and the deck fails.A through bolt, properly tightened, will nevertheless support the deck, even if the wood shrinks around it.Regards, Scooter"I may be drunk, but you're crazy, and I'll be sober tomorrow." WC Fields, "Its a Gift" 1934
I think you meant lag screw (bolt) not carriage screw. Never heard of one of those. I put lags in sometimes at a slight angle to horiz in sort of a toenail or opposing fashion /. I like the Ledgerlocks but I have not seen anything that would suggest code approval. I have read all their independent test results and seems like all data was shear (which was impressive).
Carriage bolt is a slot head threaded bolt.Lag screw or carriage screw is a hex head screw.Lag bolt is a hex head bolt.I would favor carriage bolts or lag bolts over any screw in a deck ledger application.Regards, Scooter"I may be drunk, but you're crazy, and I'll be sober tomorrow." WC Fields, "Its a Gift" 1934
Must be a left coast thing but a carriage bolt here in the southeast is not slotted but dome head with a square boss under it with a machine non tapered thread. A lag bolt with tapered thread is really a screw.
And I agree, you cannot beat the holding power of a real bolt. NC code calls for 5/8 hot dip bolt. Went through this with Matt a little while back.
Cheers, Bob
Edited 10/20/2005 10:38 pm ET by rasconc
It's just a Scooter thing. he heCarriage bolts are the same here on the left coast as over there on the wrong coast.;o)They are the same thing in the midwest, too.Domed head, square shank for a small portion of the shank below the head, machine, non-tapered threads...Never seen one with a slot.
Looking for enlightenment is like looking for a flashlight, when all you need the flashlight for is to find the flashlight.
I was just trying to be nice (:-).
So was I.Scooter knows I was jabbing, not ragging.=0)
Looking for enlightenment is like looking for a flashlight, when all you need the flashlight for is to find the flashlight.
Never seen one with a slot.
I have. They're called carriage bolts here on the North coast, LOL. But they don't have a square boss under the head.
The square-boss section under the head qualifies the unit as a STOVE BOLT (and it does not have the slot in the head). Its function is, natch, to key into a square hole cast or punched into the cast-iron (or steel) stove body...so you don't need a second wrench or a screwdriver to hold it when you install or remove the thing.
To a limited extent, stove bolts will cut their own keyway into wood and allow you to sock down/remove a new, clean nut. But gawd help ya if you need to remove the nut from a rusty one years later; you'll be reachin' fer the grinder and cussin' the idjit who used one instead of a hex-headed bolt....
Back on topic, one very good reason to use lag screws to attach a ledger board is that you get a much better overall set-up in a lot of cases if the ledger is attached to the foundation wall instead of the rim joist. And for that you need to use lead anchors and lag screws...or Hilti's and machine screws.
Advantages to setting the deck at this level instead of flush with the floor include (a) stronger connection point; (b) no danger of rot to the main house framing if you screw up on the flashing; (c) a +/- standard-height step down to the deck (instead of a partial inch or so which promotes tripping)....
Dinosaur
A day may come when the courage of men fails,when we forsake our friends and break all bonds of fellowship...
But it is not this day.
Edited 10/21/2005 10:33 am ET by Dinosaur
Most things can be pretty regional, but the definition of carriage bolt has been the same no matter where I have ever lived. I've lived on both coasts, and both north and south of these united states. And the definition of carriage bolt has been exactly the same everywhere.
Here is from wikipedia...
...
A lag bolt or lag screw is a large wood screw (with conical threads), with a hexagonal head driven by a wrench.
A carriage bolt or coach bolt has a domed head and the shaft is topped by a short square section under the head. It is used in wood where the square section is pulled into the wood as the nut is tightened, preventing the bolt from turning.
A stove bolt is similar to a carriage bolt, but usually used in metal. It requires a square hole in the metal being bolted to prevent the bolt form turning.
...
Here is the bolt that our OP needs for that ledger... ;o)
View Image
Looking for enlightenment is like looking for a flashlight, when all you need the flashlight for is to find the flashlight.
LOL - I think I would need to underpin my foundation to use those fasteners...
Edited 10/21/2005 1:20 pm ET by Soultrain
Why ?It only weighs 193 pounds.;o)
Looking for enlightenment is like looking for a flashlight, when all you need the flashlight for is to find the flashlight.
Wikipedia is an awesome resource, but you gotta remember content can be contributed by pretty much anybody, and they don't have the budget to pay professional researchers to verify things. And word usage is an especially problematic topic anyway. Ask any lexicographer....
That said, it only matters what something is called if the guy specifying it won't be doing the installation.
And that situation being the case quite often, it provides an excellent argument for precise use of language, the great lack of which is one of the worst banes of modern life. There was a story about an engineer who specified 7 19 inch cooling rods instead of seven 19-inch cooling rods for a nuclear reactor. When the seven hundred and nineteen one-inch-long cooling rods were delivered, the gov't had to pay something like fourteen million dollars for all those useless little bits of very expensive metal....
BTW--The bolt in that photo is about the size of the shackle pin used in a 500-ton towing shackle, except it's not drilled for a cotter pin (we used to use welding rods). When that shackle comes up on the towing deck hooked to the hawser and all covered with bottom mud, ya yank out the welding rod, spin off the nut, and swat the pin out in one clean shot with a 16-lb sledge.
FORE!
(Of course, you gotta be careful not to drive the pin out through the freeing port in the bulwarks, LOL. Oops....)
Dinosaur
A day may come when the courage of men fails,when we forsake our friends and break all bonds of fellowship...
But it is not this day.
Dino: 'round Hogtown, a stove bolt is a slotted domed head bolt generally with a square nut. Generally coarse thread, ie. #10-24TPI etc. The moniker comes from their once common use in stovepipe clamping hardware. Distinguished from a "machine screw", which is generally a finer thread bolt (i.e. #10-32TPI).
A carriage bolt is a domed head bolt with square wrench flats under the head. The square either fits into a square hole cut in the stock cut to prevent the head from rotating, or in most applications it simply digs into the stock behind the head as the bolt is tightened or driven into place, such that there's no need for a wrench on the head end. Used in applications where a protruding hex head would not be desirable, or where there's access only from one side for tightening. Must have been quite a few applications like that on carriages for that name to stick.
I don't bother buying long hex or carriage bolts. Threaded rod is more versatile and cheaper, and cutting with the angle grinder is effortless.
Yeah, I remember the square nuts; hadn't really noticed they were coarse instead of fine, tho. Square nuts are one of the few things I don't keep 'in stock'.
For the general reno/remod work I do, I have to keep a mix of all sorts of hardware on hand, both metric and imperial. I keep assortments of all the common small sizes in plastic divider trays, say #8-32 up to ¼-20's, but also-20s, -18s, etc. both standard and Nyloc nuts up to about 5/8 but all in hex. The metric stuff is another set of trays; 1.0's, 1.25's, 1.5's.
All the wood screws have their own trays, too. #5x3/8" up to #14x3½"; RH's; FH's; Oval Heads; and trim washers #8, 10, 12, and 14....
Plus separate boxes for specialty elec & plumbing screws, bolts, etc....
The big stuff gets stored in milk crates in original boxes; lags ¼, 5/16, 3/8; 2"-6"; Hex bolts & nuts the same; lead anchors for all three sizes; ½" and up I use Hilti's;
And the TapCons in their own milk crates and boxes; and RamSets in an Army-Surplus Ammo box (to keep my powder dry)....
And drills, taps, and dies for all of the above....
Sheesh, no wonder I never have any spare change in my pockets, LOL....
Dinosaur
A day may come when the courage of men fails,when we forsake our friends and break all bonds of fellowship...
But it is not this day.
If you are worried about what size/type of fasteners to use, hire an engineer to tell you.
There are good reasons to not use lag bolts without engineering.
What are the good reasons not to use the lag bolts without engineering? School me up.
Some people get carried away with this "hire an engineer" cr@p.
On the other hand, the thing with lag screws is that the method of installation makes for big variables in their holding power.
Let say that we have some 1/2" hex head lag screws to install. Now let's say that one guy doesn't predrill, just drives the lag bolts in 1/2 way with "his rocket" and then wrenches it down the rest of the way. (wonder if the lumber split?) Then the next guy predrills a 3/8" hole and wrenches the lag in. A third guy predrills a 7/16" hole to make it easy to drive the lag and uses a air impact wrench to tighten the lags. Just "to make sure" once the bolts are run down thigh, he turns each bolt another 5 turns using his trusty impact wrench.
In the end all 3 guys installation looks pretty much the same. The fact is that each of the installation methods gives potentially very significant difference in resistance to extraction. Shear strength of the connection is pretty much the same.
These variables are eliminated when you just suck it up and use a regular bolt, nut and washers. The same goes for when a beam is connected to the side of a post.
Why all the big hoop-la about ledger to house connections? Because this is a common failure point in deck collapses and people have been killed. You gotta put some common sense into the equation though. If the deck is 12" off the ground, use whatever connection method you feel will hold. If it is 18' off the ground make darn sure you do it right and it probably will need to be engineered.
Thanks all. I wasn't necessarily looking for fastener sizes or schedules, I was just curious as to why nails were sufficient for the rim joist, but not for deck/porch ledgers.
After all, the deck/porch joists are hung on the ledger using joist hangers & they are completely fastened by nails (unless you use L brackets & screws/bolts)...
I know what codes say, but I'm just curious as to why that is so.
Edited 10/20/2005 10:26 pm ET by Soultrain
>> I was just curious as to why nails were sufficient for the rim joist, but not for deck/porch ledgers. << The joists that are connected to the rim board on the regular house floor system are normally supported by the mud sill or wall cap plate below.
BTW - one inspection jurisdiction I build in says they are looking for the deck boards to be nailed to both the ledger and the joists, there by tieing the 2 together. Same for a joist to flush beam connection.
Yet another pointless and usless post from you. If you don't have anything useful to say, why do you bother posting ???
Bumpersticker: Your kid may be an honor student, but YOU are still an idiot.
There's always lateral movement to one degree or another between the house and the deck, expecially if the house is old and the deck new. Bolts have more sheer strength, and the best ones to use if you can, are through bolts. I always over do it, but then it's one less thing to worry about.
>>
Just about everyone uses lag screws to attach ledger boards to the house.
<<
Not really - here in NC it is state wide code to use HD gal through bolts, with nuts and washers. Nailing is required in addition. Lag screws have not been allowed for at least 10 years - and I think, longer.
The inspector i'm dealing with now will not hear of a ledger board at all. Says its not mentioned in the code book so he wont see it.
He wants me to install an I&R style flashing and joist hangers right on the rim joist.
BTW could someone please explain why everyone think I&R is self healing? Sorry its rubber not flesh, pull out the nail still got a hole.
"The inspector i'm dealing with now will not hear of a ledger board at all. Says its not mentioned in the code book so he wont see it."Three monkeys.........
I agree with Matt (post # 28). I am pretty sure the Michigan Code requires through-bolts (carriage bolts). As someone said, walking away from the house, or someone running and stopping, jumping and so forth, could pull the nails out. Or, if somehow the supports under the outside end give way (yeah, if they do you're going to have serious problems no matter how the ledger is attached, but...) the ledger could pull off the wall. Nails in hangers are angled so it would be harder to pull a joist out of a hanger (or pull the hanger off the ledger or beam).
This guy just approved my plans for the porches today. He told my specifically, "NO LEDGER". He was only concerned about his self healing flashing behind the joist hangers.
Sounds like you are good to go then!
BTW could someone please explain why everyone think I&R is self healing? Sorry its rubber not flesh, pull out the nail still got a hole.
Nano-technology--little robots bond the cut, molecule by molecule. [Just kidding--that's a couple years in the future yet.]
I know what you mean--drafting table cover material was self healing too, but it still showed the cuts. Otherwise you couldn't cut a piece off to use it! Boss, "What's taking you so long, bring that ice guard over here!" Roofer, "I cut it, but the cut heals as soon as I cut it--can't get a piece off the roll!"
If you can get access to the other side of the band joist, thru-bolts are the way to go. If you can't access it, then lags that run at least an inch in past the depth of the band joist.
Make sure you get the flashing details right! It don't matter how you fasten the thing to the band joist if in 5 to 10 years the band joist rots out. I see alot of that these days.
FYI, flashing goes up a few inches under siding (where I like to overlap with some of that stick on flashing tape to seal it to the sheathing), then an inch or 2 below the band joist, overlaping whatever siding or brick is down there. (don't seal anything there).
Next comes the deck ledger, which I prefer to stand out with some 3/4 treated every couple of feet where my bolts go thru (cut the tops of these at an angle so water will run off). this gives a little airspace between the deck leger and house for things to dry back out after the rain.
Counter flashing comes next, which tucks up under the siding with the original flashing, then folds out and back over the deck ledger. Pay special attention to corners and around doors.
More often than not, when my phone rings, it's someone wanting me to take a look at "a little bit" of rotten wood around their deck. I usually have to give them some pretty bad news when I get there.
Edited 10/22/2005 10:43 am ET by drbgwood
You sound like you have a good plan drbgwood. Is it possible that you could draw up a simple detail in the Paint program and post it here?
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