A Case Of More Not Being Stronger..A Stair Story.

A Case Of More Not Being Stronger…..A Stair Story. (This is # 4 in a series on a single flipped house.)

   nailed stringer L   nailed stringer R  

These stringers have been nailed to the deck framing with a power nailer. An air powered nailer is a great tool. It allows you to drive large nails without tiring you out. So if you want another nail there , it’s just pull.. BANG and it’s in there. And there’s the problem!

Before the common use of these tools that extra nail took some more effort. Sore arms generally set limits on the number of extra or unnecessary nails being driven.

Carpenters had code books, charts and rules that governed the type, size and number of nails used for any type of joint and size of framing. And they learned this though years of apprenticeship and work practice, training and exams.

But even carpenters had to be cautioned when these tools went into widespread use as it’s too easy to use the wrong size nail or put too many in the same area.  And Codes were changed to correct bad habits and practices.

But on this flipped property this is amateur work. No carpenter puts that many nails in this area, let alone both faces of the same piece. On the end of this stringer, in the last 2 inches of wood, how many nails are there? How much solid wood is left, wood that is not split by a nail or two?

There are too many nails (12). They are too big. And there is no solid wood left in the last 2 inches of the stringer. If you removed it and sawed it off at the 2 inch line, little scraps the size of your finger or thumb would fall to the ground.

Prior to the code changes larger framing (deeper) was required to butt the stringers against as a ledger strip had to be nailed. The ledger strip required a triangular nail pattern using nails larger than 4 inches and that required a doubling of the bearing frame.

Then the stringer was notched to bear on the ledger strip (this is where the weight was transferred) and a stringer this size would be nailed like this with two nails on one side and one in the center on the other face. The nails would be galvanized 2 or 2 and 1/2 common. (This is toe nailing, through nailing from the other side of the support frame is better.)

Nails hold the framing in place. The framing configuration transfers the weight. Nails normally are not intended to transfer weight. (The ledger board detail was an exception.)

Now the current codes treat this differently. Correctly sized metal  joist hangers are to be used. Galvanized nails can be used to mount them. Deck or outdoor screws are NOT to be used between the hanger and the supported framing – that has to be nailed – It’s a fire code requirement.

Now look at these photos again. There is no ledger strip. There are no joist hangers. The nails are too big. There are too many of them. They are not galvanized. There is not enough solid wood there to hold these stringers in place.

What keeps it from collapse?

Gravity!

Just like a ladder. And just like a ladder, a side ways push or the base sliding out will cause it to fall. Are the stringers attached to anything at the bottom?…nope!

More nails is not stronger. To many is weaker.

 

 

Original blog post on ActiveRain: Link to Blog Post

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