Thorn Coach Screw 10 × 100
Hot-dip galvanised, 17 mm hex head — box of 25
$31.00
USDStandard shipping $9.00, free over $85. Arrives in 3–6 business days. 30-day returns.
A hex-head coach screw for outdoor structure — deck ledgers, fence posts, pergola feet, anything bolted to timber that lives in the weather. Driven with a socket rather than a bit, so you can put real torque through it without touching the head.
Hot-dip galvanised rather than electroplated. The coating is thick, deliberately uneven, and keeps protecting the steel after it has been scratched, which is the property that matters on a fixing that gets hammered into place and then rained on for twenty years.
Working load limits
What this item holds, in the material you are fixing into. Every figure is a working load — the safety factor is already taken out.
Safety factor5:1 — every figure below is the tested mean divided by five.
| Substrate / condition | Working load | Notes |
|---|---|---|
| Softwood, 65 mm thread penetration, 6.5 mm pilot | 480 lb | Withdrawal. Pilot the full thread depth or the shank splits the member. |
| Hardwood, 65 mm thread penetration, 7 mm pilot | 700 lb | Withdrawal. Wax the thread — dry hardwood will seize a 10 mm coach screw. |
| Softwood, single shear, washered both faces | 520 lb | Shear. Use a 30 mm OD washer under the head; without one the head crushes into the timber and the joint loosens. |
How these were arrived at
Measured with a calibrated torque wrench and a pull rig, fifteen samples per substrate, 12% moisture content. Minimum 100 mm from an end, 40 mm from an edge.
The specification
Everything we know about this item, stated plainly. The same record is printed on the card in the box.
- Composition
- Medium-carbon steel, hot-forged head, rolled thread. 65 mm thread, 35 mm plain shank under the head.
- Dimensions
- 10 mm nominal diameter × 100 mm under-head length. 17 mm across-flats hex head, 16 mm head height.
- Weight
- 72 g each; 1.85 kg per box of 25.
- Finish & variation
- Hot-dip galvanised to a nominal 55 µm. Runs, spangle and matte grey patching are normal and are how you tell a hot-dip coating from a bright electroplate.
- Made
- Cold-formed, hardened and finished at a fastener works in the Ruhr, Germany. Boxed and counted here in Pennsylvania.
Care
- Keep the box closed and dry — the label carries the count and the batch.
- Drive with a bit that actually fits; a worn bit rounds the recess and the screw is then unremovable.
- Pilot in hardwood and near an end grain edge, always.
- Use a socket, not an adjustable wrench — a rounded hex on a galvanised head is unremovable.
Cautions
- Not for coastal or chloride exposure. Hot-dip is excellent in ordinary weather and merely adequate within a mile of salt water — that is what A4 is for.
- Not for a flush countersink. The galvanised coating is thick enough that the head sits proud of a standard countersink; drill for the coating, not the nominal.
- Not to be paired with A2 or A4 stainless in a wet joint. Zinc against stainless in the presence of water sets up a galvanic cell and the zinc goes first.
Shipping
$9.00 standard, free over $85. 3–6 business days. Full policy
30 DAYS
Returns
Unused and in original packaging. Refunded within 5 business days of reaching us. Full policy
Questions about this product
help@livwellhardware.comEvery message answered within one business day.
