Decks and IRC

[kurt]

Am I blind, or is there any deck reference in the 2006 IRC?

[Chris Bernhardt]

I've been recommending following the "Prescriptive Residential Deck Construction Guide" put out by www.awc.org, which is based on the IRC - sort of. Thats fine for residential, but there is not a like guide for commercial as far as I know.

Chris, Oregon

[Darren]

In NJ it's R502.2.2

[kurt]

Thanks all. That was quick. I got the R505.2 part, which basically says nothing.

I got your basic "the deck was built to code" push back, although it has screws instead of lags on the ledger, and there's no deck flashing. In Chicago, it's easy; they have a bullet proof code. In Evanston, it's IRC land.

Gwinnett County doesn't mean anything to these pea brains.

[Bain]

The city of Lexington has a printed list of deck guidelines that they say--I've never taken the time to check--is cribbed from the floor construction part of the IRC. Things like doubling the header if the piers are installed on < 4' centers are included, along with fastening requirements. I can zap you a copy if you want.

[kurt]

Thanks, but this is specifically about ledger connections and ledger flashing. They're pushing with "it's built to code", etc. There's nothing in the IRC about ledger connections or ledger flashing that I can find.

[Jim Katen]

Thanks all. That was quick. I got the R505.2 part, which basically says nothing.

I got your basic "the deck was built to code" push back, although it has screws instead of lags on the ledger, and there's no deck flashing. In Chicago, it's easy; they have a bullet proof code. In Evanston, it's IRC land.

Gwinnett County doesn't mean anything to these pea brains.

Well, let's see:

* Table R301.5 that says that decks have to be able to support the same load as the rooms inside the house (40 psf).

* The same table tells us that the deck's guardrails & handrails have to be able to support a 200# single concentrated load in any direction at any point along the top edges.

* Same table says that the infill area on a guardrail has to be able to support a horizontally applied 50# load spread out over a one square foot area.

* And it says, new for 2006, that, if you use glass for the handrail or guardrail assembly, you have to apply a safety factor of 4 to the loads mentioned above. (Zounds! Is that even possible?)

* Table R301.7 tells us that the hand- and guard-rails have to withstand their loads without deflection that exceeds L/240.

* Section R312 is all about guardrails and applies to decks.

* Section R403.1.4.1 says that foundations, piers, and other building supports hqave to be protected from frost. . . except for decks that are supported by a dwelling -- they don't need footings that extend below the frost line.

* Then, of course, there's R505.2.2 that says that, if the deck is supported by an exterior wall of the house, the deck has to be positively anchored and designed for vertical and lateral loads and that you can't rely on toenails or nails subject to withdrawal. (It doesn't say that you have to use bolts or lag screws, by the way.) This section also says that cantilevered members have to have connections that resist uplift.

* Table 502.3.1(2) is the table you use for joist spans that applies to decks.

* Table 502.3.3(3) is the table you use for cantilevered joist spans for balconies.

* R703.8(5) tells us that we have to use flashing at the point where exterior porches, decks, or stairs attach to a wall or floor assembly of wood-frame construction.

- Jim Katen, Oregon

[Chris Bernhardt]

Is there a citeable definition for positive anchorage?

In the research I have done the term with respect to the ledger means that the ledger should be flat grained & not vertically grained also.

Chris, Oregon

[kurt]

Wow........and all I was looking for was ledger attachment and ledger flashing stuff.......

What's frustrating is R505.2.2. It is anemic. I referenced it (because I could find that in the table of contents), but it doesn't really say much other than one can't use nails subject to withdrawal. So, in a sense, it says you can use nails. This guy used some large wood screw. I don't think it was even hot dipped.

R703.8(5) is the kicker. At least that's an authoritative prescription for flashing.

Deck stuff is frustrating. When you're talking deck failures, it's always the ledger. Or at least, darn near always. Floor loads and framing is easy to find, footings and foundation is easy, but the thing that fails (the ledger) isn't so easy. What little is said, doesn't say much, and the flashing part is in the Wall Covering section where I couldn't find it.

Thanks much........

[Chris Bernhardt]

Another argument is that the NDS doesn't cover lag bolt connected ledgers, thus neither does the IRC, so the builder can't say it conforms to the IRC prescriptively.

He would have to cite some test and get it approved by the AHJ, for which I think Woeste et. Al. have already done, test that is.

Chris, Oregon

[Jim Katen]

Another argument is that the NDS doesn't cover lag bolt connected ledgers, thus neither does the IRC, so the builder can't say it conforms to the IRC prescriptively.

He would have to cite some test and get it approved by the AHJ, for which I think Woeste et. Al. have already done, test that is.

Chris, Oregon

The IRC isn't prescriptive with regard to ledger connections. It's performance-based. So all you need is a stamped design from a PE.

The attached picture is from the last project I worked on where there was an engineering spec for the deck ledger attachment.

- Jim Katen, Oregon

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[Chris Bernhardt]

The IRC isn't prescriptive with regard to ledger connections. It's performance-based. So all you need is a stamped design from a PE.

The attached picture is from the last project I worked on where there was an engineering spec for the deck ledger attachment.

- Jim Katen, Oregon

Jim, then I take it we should be calling into question any ledger not connected per Woeste, et. al.; just like the one in your photo?

On new construction I can't recall seeing any ledgers connected like the one in your photo, at best they will be bolted in a single line spaced pretty far apart.

Chris, Oregon

[Jim Katen]

The IRC isn't prescriptive with regard to ledger connections. It's performance-based. So all you need is a stamped design from a PE.

The attached picture is from the last project I worked on where there was an engineering spec for the deck ledger attachment.

- Jim Katen, Oregon

Jim, then I take it we should be calling into question any ledger not connected per Woeste, et. al.; just like the one in your photo?

On new construction I can't recall seeing any ledgers connected like the one in your photo, at best they will be bolted in a single line spaced pretty far apart.

Chris, Oregon

I think that we ought to be looking at ledgers very carefully and evaluating them on a case by case basis. Personally, I feel that there are plenty of decks out there that will be just fine if the ledgers are simply attached with Simpson Strong Drive screws and well flashed to keep water out from between the ledger and whatever it's attached to.

On the other end of the spectrum is the method in my picture and the methods that Woeste offers. In our area, there's also the Metropolitan Area Structural Engineering Reviewers (? is that right?) MASER. They offer a precriptive deck document that's supposedly based on the Oregon Residential Specialty Code. Haven't I sent that one to you?

- Jim Katen, Oregon

[kurt]

I think that we ought to be looking at ledgers very carefully and evaluating them on a case by case basis. Personally, I feel that there are plenty of decks out there that will be just fine if the ledgers are simply attached with Simpson Strong Drive screws and well flashed to keep water out from between the ledger and whatever it's attached to.

I agree. There's lots of ways to do it that work fine, if there's just some decent bolts/lags/screws, and some flashing.

So, of course, the IRC doesn't address it that way.

POI, bolted ledgers should have the bolts zigzagged like the pic; if they're inline, the ledger will zip split down the middle.

[Brandon Whitmore]

MASER. They offer a precriptive deck document that's supposedly based on the Oregon Residential Specialty Code. Haven't I sent that one to you?

- Jim Katen, Oregon

Jim,

I'd like to see that document if you have it handy.

[Jim Katen]

MASER. They offer a precriptive deck document that's supposedly based on the Oregon Residential Specialty Code. Haven't I sent that one to you?

- Jim Katen, Oregon

Jim,

I'd like to see that document if you have it handy.

It's in my other computer -- I won't have access to it for at least another day. I'll send it to you directly then. I remember trying to upload it here but it's way too big a file for that.

[Brandon Whitmore]

Thanks Jim,

There's no big rush if you don't get around to it for a while.

[Darren]

https://www.inspectorsjournal.com/forum ... IC_ID=9020

Here's a supplement to the IRC deck attachments.

[Neal Lewis]

The attached picture is from the last project I worked on where there was an engineering spec for the deck ledger attachment.

- Jim Katen, Oregon

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Jim, I'm not seeing the flashing in the photo. And is the ledger installed directly over the siding?

[Tom Raymond]

Then of course there's the deck designed and built by an engineer on his own home. The pictures speak for themselves.

Tom

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[Bain]

Check out the pier/non-pier and beam system beneath the outer sections of the deck from this afternoon's house.

I wonder if I could find something in the IRC that would prove how dopey it is.

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[Jim Katen]

. . . Jim, I'm not seeing the flashing in the photo. And is the ledger installed directly over the siding?

The siding is installed as a rainscreen system and the deck ledgers are incorporated into it. The flashing is behind the ledger with spacers separating the two.

- Jim Katen, Oregon

[Jim Katen]

Check out the pier/non-pier and beam system beneath the outer sections of the deck from this afternoon's house.

I wonder if I could find something in the IRC that would prove how dopey it is.

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MC Escher Deck Construction, LLC.

- Jim Katen, Oregon

[sepefrio]

From Saturdays inspection....Deck built to code BFUM 3427.3

New floating pier design (yes there is 2in between pier and footing)

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And here is how we prevent pier from contact the soil, sit on on a retaining wall member.

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[Brandon Whitmore]

Jim,

I'm looking through the MASER document. I have a concern with this:

9.

Decking must have a span length such that each

board bears ona minimum of two joists.

Really? Span to 2 entire joists? Are they meaning that with say 16" o.c. framing that you only have to have a 16" surface board?

I've always thought at a bare min. you should span to 3 joists

Also,

I think you left out key word here:

* Section R403.1.4.1 says that foundations, piers, and other building supports hqave to be protected from frost. . . except for decks that are

not

supported by a dwelling -- they don't need footings that extend below the frost line.

Bold added where I think you left out a word.

Thanks again for sending me the document.