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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Carried And Through: ……Bolts Out Of The Blue

Carried And Through: ……Bolts Out Of The Blue

Jay Markanich’s recent blog raised a debate about the use of carriage bolts in outdoor wood structures. Some appear to claim that they are an inferior fastening technology. I say consider the source.

Some facts: Carriage bolts were designed to be drawn into the wood to lock the head in place and allow tightening of the nut. That system works fine as long as the bolt holes were not too big in the first place and as long as the heads don’t slip when torque is applied.

This is ‘the carriage bolt school technology‘ and it is quite sufficient for the weight and stresses that these structures are subjected too. A little maintenance is required over time to retighten the bolts and keep water out of the head area. Water entry at the head area can degrade the wood there, but it would have to be extreme for the connection to fail.

Simpson Strong-Tie people are selling a product. From a strictly engineering standpoint more torque can be applied to a properly washered through bolt. In theory the joint can be clamped tighter, but both bolts have the same load carrying strength for their size.

So through bolts can be made tighter and as their installation does not involve crushing wood fibres they have lesser incidence of wood deterioration risk around the heads (Note that they do have some, just not as much risk).

Technically the Strong-Tie sales peoples claim that their opinion about through bolts being better is supportable. But stating that carriage bolts are categorically inferior is pushing it. Remember they are selling a product they believe in so a little bit of overstatement is forgivable.

Carriage bolts properly installed and maintained are fine. Suitably large bore washers can be installed under the heads if the wood species is problematically soft or constantly wet.

Carriage bolts have the advantage in that the heads are smooth low profile forms that do not protrude to skin shins or knuckles and catch on ropes.

Carriage Bolts….carry on!

 

 

This article was written by Robert Butler and was inspired by the original blog article mentioned above by Jay Markanich and written in part as a comment on this follow-up blog. Link through to these blogs for other opinions and more discussion on the subject.

N.B. This might seem as a serious debate and it is to a point. Both products and systems are structurally functioning methods. The debate is really about degree and longevity.

Contrast that with the frequently discovery of structures built with out benefit of either fastening system. This is where Jay’s original blog and indeed most blogs on the subject stem from.

 

 

 

 

Original blog post on ActiveRain: Link to Blog Post

Don’t Trim Those Toe Nails!

This is a serious problem that is prevalent because of amateur or un-informed workmanship. The only railing systems that can be attached onto the deck surface are solid metal types designed to be surface mounted. All wood systems have to pass through the decking and be through bolted into the framing.

This article is written by an experienced Virginia inspector. His tone is a bit sarcastic but he illustrates the point very well.

Toe nailing is a valid carpentry technique.  But for the most part it is a temporary tacking of one thing to another by nailing two things together at an angle.  Then proper attachment can be made.  Toe nailing is seldom, if ever, intended for long-term attachment or support with heavy material.

Walking around this deck, only about 4′ high, I noticed that every single guardrail post had been toe nailed to the decking!

Don’t trim those toe nails!

You can see how substantially attached that post is to the deck (he sarcastically notes).  Many wobbled a lot!  Rock on dude…

Despite the VERY FINE paint job, this is a huge problem.

Sure, the deck is only 4′ high.  Do you want to fall 4′, land on top of a broken guardrail, and land at an angle you can’t control?

Didn’t think so…

Where do people end up when they go out onto a deck?

The guardrail!  They lean.  They put weight.  They ASSUME it’s safe.

The code would like the guardrail to easily support about 200 pounds.  That is all well and good.  But often more than one person is leaning against the rail!  Remember, the code is a MINIMUM STANDARD!  And a well-attached, or properly-attached, post can support far more than 200 pounds.  How should deck posts be attached?

There are various ways.

They can be attached on the outside of a joist, or the inside.  Two can be attached surrounding a corner.

BUT ALL MUST BE ATTACHED WITH TWO THROUGH BOLTS THAT ARE SEPARATED FROM THE WOOD WITH LARGE WASHERS.

The bolts, washers and nuts should be of the same material that resists corrosion (stainless steel, galvanized or zinc dipped).  The most common would be galvanized.

Carriage bolts are not good bolts to use!

Why?

The round head is not wide enough and when the nut is tightened the round head actually gets sucked into the wood.  And the square end under the round head does not accept a washer.  Carriage bolt use was emphasized by the engineers at my recent Strong-Tie seminar.  Carriage bolts should not be used for post or beam attachment.

There are other criteria regarding guardrails that are important, but not the point here.

Proper attachment affords strength and safety.  Safety is always the bottom line.

My recommendation:  when you see a deck, have a look!  Feel its strength as you walk on it or carefully lean on the guardrail.  Check attachments.  How does it make you feel?  And get an inspector to have a look see should you put a contract on the house!  Decks COMMONLY have problems.  You want to know what they are!

 

Jay Markanich Real Estate Inspections, LLC

Based in Bristow, serving all of Northern Virginia

www.jaymarinspect.com

 

Original blog post on ActiveRain: Link to Blog Post