National Occupational Competency Testing Institute (NOCTI) Carpentry Practice Exam

Which type of fastener is typically used to connect the forms at the edges or corners during concrete work?

1. Single head nails

2. Screws

3. Double head nails

4. Staples

The correct answer is: Double head nails

Double head nails are specifically designed for applications where the fastener needs to be removed easily after the concrete has set. In concrete work, forms are used to shape and hold the poured concrete until it hardens. Double head nails allow for quick initial assembly of these forms and, once the concrete has cured, facilitate the easy removal of the formwork without damaging the structure or the surface of the concrete itself. The first option, single head nails, do not possess the same removable qualities, as they are meant to be driven in flush with the surface and can be challenging to extract without damaging the form or the surrounding concrete. Screws, while they provide a strong fastening option, are generally not as practical for formwork because they take longer to install and remove compared to nails. Staples may be useful in certain applications but lack the strength and holding power necessary to securely fasten forms during the pressure of wet concrete.