The Elephant In The Room – Stringer Strangeness / Stringer Stress

 

The Elephant In The Room – Stringer Strangeness / Stringer Stress: Whats WRONG Here?

stair / floor framing

This is under the basement stairs of a nice looking home less than 2 years old.   There are a few things wrong in this photo.

Can you spot all five structural defects?

Here are a few hints;

1 – The riser of the last tread and one joist do not a double trimmer make.

2 – Toe nailed joists do not carry weight, Forever or for long.

3 – Nails are pins to hold framing in place. Weight bearing framing has to be under the load.

4 – Zippered nailing or stitched nailing will not be secure over time. A power nailing defect.

5 – And, yes..the elephant in the room; the stringers are too short on one end. Guess which end.

 

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1

missing double header framing

illustration framing

It’s obvious: one does not look like the other.

There is neither doubled header or trimmer joists present.

What you see in the photo is only a single joist and the face or ‘riser’ of the top tread is nailed to it.

But that is a finishing piece and has no structural strength or function.

So there is no doubled header floor joist at all and even it there were it would be in the wrong position.

In fact there is no correspondence between the text illustration and the actual construction here at all.

Corrective supports and framing are required to make this safe and secure.

I wouldn’t bother to get a price from this builder. No point.

 

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2

error no joist hanger

You’ve seen movies where mountaineers climb rock faces with minuscule toe and finger holds. That may be  fine from the comfort of your chair.

But it’s not what you want to see in your floor framing.

Toe nailing is a carpenters technique using small nails at an angle at the ends of studs and other framing to position, aline, and hold parts in place until other cladding or finish materials are applied. There is no strength in these joints and they can easily be adjusted in various directions.

Here this sideways nailing was used but with bigger nasils. They will hold for a time, but not for all time.

Joist hangers are required here, or else you have to go old school. Old school is double notched joists meeting ledgered beams. It works well, just takes a lot more wood and space. Or you could use joist hangers.

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3

face nailed to stud

It’s partially obscured by the pipe but we can see enough to know that the trimmer joist is only been face nailed to the stud.

It’s the stud that carries the load so it should shoulder it. Meaning that it should be under the joist, at least by the thickness of the joist, or the joist should be notched into the stud.

There is no other framing around to carry the weight for this part of the floor and the stairs. Doesn’t matter if there may be a big engineered truss or wood joist on the other side of that wall. There is nothing right here.

Nails, no matter how big are just pins used to hold wood in place. The wood has to carry the compression load. Nails don’t cut it over time. Wood drying shrinkage, rust and vibration will weaken them. (Screws are worse – no shear strength.)

If the wood parts are big enough then bolts can be used but here thats not the case. Cripple studs must be added to the face of those studs to tranfer the load to the slab shoe plate.

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4

too many nails    I call this nailing defect ‘zippering’ because when large bore nails are peppered close together they can cause the wood to be weakened at that place or line.

This effect is just like the perforations on the tear line of a cardboard box or other packaging. The nailing has punched out material there of crushed fibers so now it can easily be broken at that spot.

Here we can see the space from the tread notch to the bottom edge of the stringer (as it follows the stud) has been nailed repeatedly in a tight line.

The nails are holding for now and the problem is not obvious but as the wood ages and dries it won’t ‘grip’ the nails as tightly and the vibration from the stair usage will start to loosen them. Failure will begin with a bounce and squeak developing in the stairs. These nails are all that’s holding up this stringer.

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5

major error

Here we have the big goof. The elephant in the room.

The photo just shows one stringer but they are both are too short. They don’t meet and transfer load to the floor frame as they should. Have a look at the stringers in Figure S1 (above) to see the correct assembly.

I’ve seen similar errors outside on deck construction, which often gets done non-professionally. When I think back to the last time I saw that error I quickly realize that it was only about an hour ago, outside at the rear deck of this house. Hymn….

The frameing at the main stair to the second floor is completely unaccessable as it is behind finished walls and ceilings. Hymm….

So far this guy is batting O and 2. Will he strike out?

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This array of errors is also just one more example of why it is just as important to have a new home fully inspected.

Just because it’s new,  doesn’t mean it’s right.

 

Original blog post on ActiveRain: Link to Blog Post

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