double-headed nail

double-headed nail, scaffold nail, form nail

double-headed nail
A nail having two heads, one above the other; the upper head is driven with a hammer, and it is used to withdraw the nail; the lower head bears on the surface into which the nail is driven; used on temporary structures such as scaffolds, formwork, etc.
References in periodicals archive ?
Jackson didn't assign blame, but he said it was interesting that the culprit was a double-headed nail of the sort used for building concrete forms on, for example, highway projects.
The two 1/4" holes are where you will drive two double-headed nails when you hang the box on a tree-trunk--the holes so your dry boards won't split, and the double-headed nails so you can easily take down the box when you have captured a swarm to take home.