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Lesson 3 of 3

The failed inspection
is the expensive one.

Fasteners are a rounding error on the takeoff. They are also the only line that can get a framed deck torn back to the joists on inspection day. This page is about what the wrong box costs once the labor to undo it is counted, and it is written for the person paying for the job as much as the person nailing it.

Run Your Numbers (615) 792-5156
Section drawing of a deck ledger at the house: DTT2Z tension tie on the deck joist, half-inch threaded rod through to a matching tie on the floor joist inside, floor sheathing nailed at six inches to the joist
The deck-to-house lateral connection: a DTT2Z on the deck joist, a 1/2-inch rod through the rim, and a matching tie on the floor joist inside. Simpson Strong-Tie Wood Construction Connectors catalog, deck tension ties.
The math the takeoff leaves out

Four ways a cheap line becomes a dear one.

The wrong nail in the hanger. The crew has a box of 1-1/2 inch hanger nails and the LUS26 calls for 0.148 by 3. The catalog says that swap leaves 0.77 of the download. In a hanger built for 0.162 by 3-1/2, the short nail leaves 0.64 and uplift is not allowed on some rows. The inspector reads the stamp on the hanger and the nail heads and asks for the row. Every joist in the run gets its nails pulled, or gets a new hanger. The nails were the same price either way.

Bright fasteners in treated lumber. A box of bright common nails or electroplated screws goes into a treated deck frame. Simpson puts bright and electroplated in its low corrosion tier, for dry service. Treated wood in the weather is medium at best, and the codes call for hot-dip galvanized or stainless in it. Koppers, which treats most of the lumber on our yard, prints the same minimum. Nobody publishes the year those fasteners give up; Simpson says plainly it cannot estimate service life. What is published is that they are in the wrong tier, and the fix is a deck frame with a thousand fasteners in it that should have been a different thousand.

The deck ledger. The ledger is bolted, the joists are hung, and there is no lateral connection to the house. Simpson's catalog describes the IRC provision: 1,500 pounds at two places, or 750 pounds at four, and it sells the DTT2Z and the DTT1Z to meet each one. Missing, it is the item a deck fails on. Added after the fact, it means opening the floor from inside the house for the DTT2Z detail, which is exactly why Simpson designed the DTT1Z to reach the plates and studs from the deck side.

The re-do. Every one of these is fixed the same way: the crew comes back, the connectors or fasteners come out, and the right ones go in, on a day that was scheduled for something else, while the inspector waits for a second visit. The fasteners for the re-do cost about what they cost the first time. The labor is the whole bill.

The question is not whether the right box costs more than the wrong one. It is whether the difference is bigger than the chance of a re-do times what the re-do costs. That is arithmetic, and the calculator does it with your numbers.

How to use this page

Bring two boxes. We do not put prices on the site.

Count the connectors on the job, or the fasteners in a run of the same kind: every hanger in a floor, every tie on a roof, or all the screws in a ledger. Read the fastener column for that connector to get the count per connector; the catalog row or our counter will give it to you. Then take two box prices from wherever you buy, one for the fastener the row names and one for the fastener the crew would reach for otherwise, and the count in each box.

Then two numbers only you can supply. How likely is it that the wrong fastener gets caught, by the inspector or the engineer, by the deck in ten years, or by nobody. And what would it cost to come back and put it right: the crew day, the connectors, and the return trip for the inspection. The calculator multiplies the two and calls it the expected cost of the wrong box, and sets it against the difference on the bid.

It does not know which fasteners you are comparing. It only knows arithmetic.

What the makers publish

Numbers to start from, not to stop at.

Counts per connector, from the Simpson tables: LUS26, eight 0.148 by 3 nails. LU26, six 0.162 by 3-1/2 and four 0.148 by 1-1/2. H2.5A, ten 0.131 by 2-1/2. ABA44Z, six 0.148 by 3. ABU44Z, twelve 0.162 by 3-1/2. DTT2Z, six SD screws and one 1/2-inch bolt.

Substitution factors, from the same catalog: 0.77 for a 1-1/2 inch nail where 3 inches is called for at 0.148; 0.84 for a 0.148 by 3 where 0.162 by 3-1/2 is called for; 0.64 for a 0.148 by 1-1/2 in that hanger. Overdriven nails: no reduction only if the four conditions on page 26 are all met.

Corrosion tiers: bright and electroplated are low; A153 hot-dip and the coatings with a code report are medium; 304 and 305 stainless high; 316 stainless severe. Treated wood in the weather starts at medium.

Service life: none published. Simpson says it cannot estimate one. Use your own judgment in the chance box below.

Cost Over Time

The right box, the wrong box, and the re-do.

Nothing you type here is sent anywhere. It runs in your browser.

The job

Box A (the fastener the row names)

Box B (the fastener on the truck)

The re-do

Counts per connector are in the Simpson table for the model stamped on the steel: an LUS26 takes eight, an H2.5A ten, an ABU44Z twelve. The chance and the re-do cost are yours; no maker publishes a service life or a failure rate, and this page does not invent one.

320 fasteners across 40 connectors

Box A, boxes needed
–
Box A, cost for the job
–
Box B, boxes needed
–
Box B, cost for the job
–
Difference on the bid
–
Expected cost of a re-do (chance times cost)
–
Wrong box, all in
–
Break-even chance
–

Fill in both boxes to see the comparison. Add a chance and a re-do cost to see what the wrong box really costs.

Boxes needed are rounded up to whole boxes. Expected cost of a re-do is the chance you entered times the re-do cost. Wrong box, all in, is Box B for the job plus that expected cost. Break-even is the chance at which the two come out equal: above it, the right box is the cheaper one.

Before You Price Fasteners

Know what is holding it together.

Three short reads on fasteners and connectors. Written for the builder who has to answer to the money, and for the inspector.

Lesson 1 What you are paying for Coatings and corrosion, shank and thread, structural screws vs nails, connectors and the fasteners they require. Each one you can check in the bin. Read it → Lesson 2 Read the box Corrosion classes, treated-lumber compatibility, ICC-ES reports on structural screws, and the connector catalog table the inspector reads. Read it → Lesson 3 The failed inspection is the expensive one The wrong nail in the wrong hanger, rusted fasteners in treated lumber, and the deck that gets re-done. Run your own numbers. You are here

Frequently Asked

Fastener cost over time, answered.

What happens if the wrong nails are used in a joist hanger?
The hanger carries less than its table says, and the catalog tells you how much less. Simpson publishes the factors: a 0.148 by 1-1/2 nail in a hanger that calls for 0.148 by 3 leaves 0.77 of the download. A 0.148 by 3 in a hanger that calls for 0.162 by 3-1/2 leaves 0.84, and a 0.148 by 1-1/2 in that same hanger leaves 0.64 with uplift not allowed on some rows. Some substitutions are simply not allowed. When the inspector reads the stamp on the hanger and the head on the nail and they do not match the row, the connection is not the one on the plan, and the fix is pulling nails or pulling hangers. The general notes say it in one sentence: incorrect fastener quantity, size, placement, type, material, or finish may cause the connection to fail.
Are overdriven nails in a hanger a problem?
Sometimes. Simpson defines an overdriven nail as one whose head deforms the steel, and says no load reduction applies only when four things are all true: the connector is 14, 16, or 18 gauge; the head is not driven past flush with the steel; the nail went through an existing hole without enlarging it; and the steel around the hole is not torn beyond the dent of the head. A gun set too hot on a thin strap fails that test, and so does a nail driven beside the hole instead of through it. The catalog says to take extra care with power-driven nails for exactly this reason.
What is the deck lateral load connection the inspector asks about?
The IRC provision that ties the deck to the house frame so it cannot pull away from the ledger. Simpson's catalog describes it two ways: a 1,500 pound connection at two places per deck, which its DTT2Z is made for with six SD screws or eight 0.148 by 1-1/2 nails and a 1/2-inch bolt, or a 750 pound connection at four places, which its DTT1Z makes to the top plates, studs, or headers with a Timber-Hex screw so nobody has to open the floor inside the house. The catalog notes that its brick veneer ledger connector does not replace this requirement. It is a handful of connectors and the screws that come with them, and it is the item a deck fails on when it is missing.
How long will bright nails last in treated lumber?
Nobody prints a number, and that is the honest answer. Simpson says outright that it cannot estimate the service life of connectors and fasteners because too many variables are involved, and that its corrosion testing gives relative rates that do not correlate to a life expectancy. What it does say is that bright and electroplated fasteners are its low tier, that treated wood in the weather calls for the medium tier or better, and that hot-dip galvanized or stainless is what the codes require in treated and fire-retardant wood. Koppers says the same for its own wood. The calculator on this page does not pretend to know the year a bright nail gives up. It asks you what a re-do costs and how likely you think it is.

Stop By the Desk

Let’s talk it through in person.

Bring your plans or just your questions. We’ll get you squared away.
119 Cumberland St, Ashland City. The coffee’s on.

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