Lag Screw

Hexagon head wood screw (coach screw, “lag screw”) – a fastener, a metal shank with coarse-pitch thread.

The technical characteristics of the product (international designation DIN 571) comply with the requirements of GOST 11473-75.

Product features

According to the standard, the working diameter of a lag screw ranges from 6 to 20 mm; the length (to the head) – from 20 to 200 mm; the threaded section is at least 0.6 of the length (it may sometimes extend all the way to the head). The width across flats is from 10 to 30 mm. Depending on the material and surface finish, the following wood screws are produced:

• made of low-carbon steel, plain (uncoated);
• made of stainless steel;
• zinc-plated;
• brass.

Application, installation rules

The lag screw provides a connection designed for increased loads. The hexagon head wood screw is used to fasten battens and joists when erecting structures from squared logs and timber, assembling wooden structures, and installing plumbing fixtures. Combined with wall plugs, lag screws are installed into brick or concrete. Installation is carried out in stages:

• a hole is drilled – its diameter corresponds to the diameter of the thread roots of the screw;
• the lag screw is driven in clockwise using a hex wrench or a power driver with a hex bit.

To increase the contact area and reduce pressure, an oversized washer DIN 9021 is placed under the head.