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Deck stair stringers

M

MikeC

Silver Member
Joined
May 17, 2012
Messages
230
Location
NW Pennsylvania
I am having difficulty with this one. I know that I don't like it one bit, but I cannot find any stringer regulations in the IRC. I almost feel bad for this guy. He is a homeowner who is trying to do the right thing, but just keeps screwing up. The last trip consisted of me telling him that he had to take ALL of the screws out of the joist hangers and replace them with appropriate 10d nails. I also explained that he would need to redesign the stairs because there was only about an inch of wood left at the notch.His wife called me this morning and said that he was ready for me to come and check it out again. This is what I find -View attachment 1363Is this addressed anywhere in the 2009 IRC?

View attachment 1703

View attachment 1703

/monthly_2012_06/0605121328.jpg.bdf4a0ab8067b10857d277a9ff35376d.jpg
 
I guess you're right. If I draw a line from the inside of the notch, there is still about 2.5 inches of wood between that and the notch for the treads. Three stringers and 3 steps, okay. I still don't like it and wouldn't do it that way if it were my project.
 
That's fugly....but not sure what you could hang your hat on. Could ask for engineering, but is it worth the battle for what does appear to be 3-4 rises? I think I would just move on myself.
 
Hi Mike,

When I was inspecting I always tempered my correction notices with common sense. In your case, I would never accept drywall screws but deck screws are a no brainer given that they are long enough. Refusing to accept corrosion resistant screws just because the hanger manufacturer never tested the hanger with screws might be reasonable on an exit stairway in a commercial building but would be an egregious waste of your time on any residential stairway.

Bill
 
I'm going to respectfully disagree, while deck screws may "work", having experience of snapping off more than a few, they have hold down power, but are brittle, not good for sheer. I would not accept them even in a residential app.
 
FWIW, all of the floor joists of the small deck had screws in the hangers. I don't care if it is Mike Holmes, the screws are coming out. The manufacturer says nails and the code says nails.
 
"I don't care if it is Mike Holmes, the screws are coming out. The manufacturer says nails and the code says nails."

The mfr wants nails. Why stray from the path?
 
The DCA6-09 and included commentary provides framing information for stairs based on IRC R301.5.

Screws are available for metal connectors; check for example Simpsons Strong manufacturer’s installation guide for approved applications.

Francis
 
They also make a short fat-shanked nail for hangers that does not penetrate thru other side of 2-inch nominal.

What I see most often from amateurs is the first tread dropped one riser and bearing only an inch or so against the deck band. They try to save on length of stringers that way.
 
Francis Vineyard said:
The DCA6-09 and included commentary provides framing information for stairs based on IRC R301.5. Screws are available for metal connectors; check for example Simpsons Strong manufacturer’s installation guide for approved applications.

Francis
Click to expand...
Two code reports for Simpson are ESR 3096 and ESR 3046 referencing 2009 IRC and IBC for screw fasteners
 
ask him to add a 2x6 on the inside of the stringers if you're really worried about it. or, you could suggest that he start with 2x12 next time. i keep a library of trade related manuals at my desk. these are the ones i used when "on tools". if i see someone struggling, i'll lend 'em the book, 'cause i'll be back. it's made the difference in few situations. what ever it takes to get the point across and help educate. ilearn something, every day

there ain't many problems that a man can't fix, with $700.00 and a 30.06
 
The nails or screws should be the proper quantity, length and shank diameter for the hardware and application. Per the hardware manuf’ers. tables for a given (tabulated) allowable load. And, new nails in existing, pre-drilled, screw holes of unknown size are not worth a damn. It might be better to pick a new hanger, so the nail holes don’t line up with the existing screw holes.
 
MikeC - it looks as if the deck is free standing and with 3 stairs its probably close to or less than 30" above grade, if this is so than a permit may not be required in Pa.

UCC 403.62

© A permit is not required for the exceptions listed in § 403.1(b) (relating to scope) and the following, if the work does not violate a law or ordinance:

(8) Installation of an uncovered deck where the floor of the deck is no more than 30 inches above grade.
 
dhengr said:
It might be better to pick a new hanger, so the nail holes don’t line up with the existing screw holes.
Click to expand...
The holes are always in the same place.
 
Keystone said:
MikeC - it looks as if the deck is free standing and with 3 stairs its probably close to or less than 30" above grade, if this is so than a permit may not be required in Pa. UCC 403.62

© A permit is not required for the exceptions listed in § 403.1(b) (relating to scope) and the following, if the work does not violate a law or ordinance:

(8) Installation of an uncovered deck where the floor of the deck is no more than 30 inches above grade.
Click to expand...
Deck is higher than 30 inches. FWIW, I am not even worried about the screw vs. nail issue. That is closed. My concern was the notching of the bottom of the stringer being so close to the cut for the treads. I was imagining the wood splitting from the hanger notch down to the tread.

Today was when the 30 inches came into play. I guy's friend built a severly substandard deck over a weekend without applying for a permit. His friend supposedly builds decks eveyday. This one was built to hold a hottup. Yeah, whatever ...... I left a list of corrections with his wife. He called me on the phone quite mad about the list I left him. I let it slip that the hill on the side was the only reason he needed a permit in the first place. Now he wants to bring in some fill and raise the grade to less than 30 inches out to 36 inches away from the deck so I can't make him fix it. I explained that it doesn't change the fact that it needs to be built safely.
 
MikeC said:
Now he wants to bring in some fill and raise the grade to less than 30 inches out to 36 inches away from the deck so I can't make him fix it. I explained that it doesn't change the fact that it needs to be built safely.
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It changes who gets to decide what's safe.
 
Codeworks:

I like your approach. Do a little teaching and explaining along the way, it doesn’t really take that much more time and effort. Explain why the code requires it this way, assuming you know, and you should, or you have a heck of a time convincing the other guy of the importance of that detail, done this way. You might even make a cooperative friend rather than a resistant, disagreeable builder. And, you might learn something along the way too. Good for you.

One the one hand, you shouldn’t have to conduct a builders apprenticeship program just so a guy can screw-up his own deck or building. But, in our effort to fully democratize the building business, where anyone should be allowed to build anything, if only they can follow a complex enough code, which will never cover everything under every situation; we have kinda brought this on ourselves. Then we ask/expect you to interpret and enforce this mess. The codes and standards have gotten so complex in the last 10-15 years, that none of us understand and know them completely, or really learn to use them before they change again. And, certainly none of us know it all, but we should know the intent of that section and what is really important about it, and then what was just so much Ph.D. thesis b.s. material which was added to force a new code edition printing.
 
Follow Codeworks & dhengr, scab and tack a two by, do a lil splaining.

If he still doesn't get it, require a pre-built and as-built grading plan along with a deck permit and make the builder aware, the revisions may have to go before the planning commision due to land development concerns. The later is a little extreme so scratch that but grading plans may be an alternative.
 
ICE:

Regarding your post #15: “The holes are always in the same place.” Since you were so emphatic, I trust that you guarantee this. And that it applies to all models of all joist hangers, by all product manufacturers, under all situations. Otherwise, it’s a profound profundity that on the same model joist hanger, made by the same manufacture, the holes will probably be in the same location from piece to piece, since they gave up individually hand forging these items a few years back. And, I would expect this would be true of an identical model joist hanger, even if new and fresh off the shelf. Alternatively, one could move the house and the deck to another lot, then the holes wouldn’t be in the same place either, if that’s what you thought I meant. But, the take-away knowledge I intended to convey would still apply.

The primary idea was that nails driven into preexisting holes have very poor holding power and design values, however you cut it (notch it), locate it or place it. So, then, be careful using the tabulated joist hanger load values.
 
Time to stir up a little hate and discontent. It's Thursday, what the heck?

INTENT: The purpose of this code is to establish minimum requirements to safeguard the public safety, health and general welfare..... Section R101.3.

The intent of any stairway is to provide a safe means of travel from one plane to another. Regardless of whether the stairs are four riser or fourteen risers, if they are likely to fail, they need to be fixed. The larger the notch, the more likley they are to fail in shear. What do you say to the person using this stair when it comes apart while they are using it and they are potentially injured for life, perhaps ending up in a wheelchair. But it was only four risers, you shouldn't have gotten injured on a stair having only four risers.
 
dhengr said:
ICE:Regarding your post #15: “The holes are always in the same place.” Since you were so emphatic, I trust that you guarantee this. And that it applies to all models of all joist hangers, by all product manufacturers, under all situations. Otherwise, it’s a profound profundity that on the same model joist hanger, made by the same manufacture, the holes will probably be in the same location from piece to piece, since they gave up individually hand forging these items a few years back. And, I would expect this would be true of an identical model joist hanger, even if new and fresh off the shelf. Alternatively, one could move the house and the deck to another lot, then the holes wouldn’t be in the same place either, if that’s what you thought I meant. But, the take-away knowledge I intended to convey would still apply.

The primary idea was that nails driven into preexisting holes have very poor holding power and design values, however you cut it (notch it), locate it or place it. So, then, be careful using the tabulated joist hanger load values.
Click to expand...
Just my luck to run into somebody with first hand experience.
 
Fatboy:

The argument/discussion might go something like this... The stair stringers act kinda like rafters against a ridge board (rim jst.) and on an ext. brg. wall (the support at grade). That rim jst. better be strong enough to take the thrust and so should the support at the bottom of the stairs. Or, due to stringer flexure the stringers could tend to pull away (walk away) from the deck over time. None of these hangers are particularly good for a tension load along the axis of the rafter or stringer. The top of the stringer is generally in compression under load so the notching for treads and risers is not harmful in the normal way we think of notching, but you should still be careful not to over cut them. However, this notching does reduce those stringers to approx. 2x4's (~1.5x 2.7"), and three stringers/rafters should probably be o.k. for that loading and span. But now, what do you think of a notch almost half the depth of the 2x4 (~1.1") at the reaction point and only a few inches (~4.7") from the top notch. The code does talk to that. Furthermore, there is a weak grain line running down from the large knot toward the first notch right where the horiz. shear stress is the max. That’s just a pretty messy detail and condition, not covered by a specific code paragraph, and I can’t say it will fail either, it’s just not a good detail. And, MikeC expressed the correct concern in his post #3, the existing hanger looks like a USP hanger. Remember much of the loading on a stringer like this is dynamic and impacting, not static.

The codes, however complex they try to become to cover every condition, will never be able to cover everything, under every situation, when we allow people to pretend they are builders, who just about know the difference btwn. a saw and a hammer, and think screws must be better because you don’t have to bend them with that tool other than a saw. Some of these situations require some bldg. inspector or engineering judgement for the safety of the builder and his family or guests. I feel sorry for some of these people too, they are not intentionally trying to antagonize us, they just know not what they are doing. Here again, a “lil splainin” about potential splitting down the stringer length and teaching and the comment that we want this to last a long time and be safe for your family, might go a long way. A rafter hanger like Simpson’s LSU26 or LSSU28 might be a better choice because you can bend the bottom seat up to match the stringer slope, they also have a newer rafter hanger LRU26 or 28 which might be the best choice. USP’s light slope hangers LS268 are like the LRU. They all protect the bottom edge of the stringer and eliminate the notch on the bottom edge. Note that a rafter or stringer heel hanging below the ridge beam or rim jst. will tend to (might) split from the bottom of the beam almost as if it were notched at that elevation, because the heel is unprotected/unsupported. And, I believe the code says something about rafters hanging below the ridge beam or hip and valley rafters also. Another high horiz. shear stress location unsupported.
 
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