The ‘blue screw’ 30 October 2018

CONFAST® hex head concrete screw – often called ‘blue screw’ due to the blue coating that helps the screw resist rust – is designed to be used when the screw head can protrude above the surface of the item being fastened – allowing for the removal of the screw.

The CONFAST® hex concrete screw is considered a light-duty fastener in both the 3/16 inch diameter and ¼ inch diameter. Holding values increase based on the depth of embedment, providing that minimum and maximum embedment requirements are met – with the holding values differing based on the base material into which the CONFAST hex concrete screws have been installed.

To determine the size of the CONFAST hex concrete screw required for a specific application, an installer must consider the size of the hole in the fixture, the thickness of the item being fastened and the weight of the item. The ¼ inch diameter holds slightly more weight than the 3/16 inch CONFAST hex concrete screw. The minimum length of screw required for any job is determined by adding the thickness of the material to the minimum embedment depth of 1 inch, and the maximum length CONFAST hex concrete screw is equal to the thickness of the material being fastened plus the maximum embedment depth of 1 inch – ¼ inch.

For minimum holding values, the screw’s minimum embedment in the base material is 1 inch and the maximum embedment is 1 inch – 3/4 inch. A ¼ inch hex nut driver is required for the 3/16 inch, and a 5/16 inch hex nut driver is required for driving the ¼ inch CONFAST hex concrete screw.

The screw also features a hex slotted washer head – 3/16 inch diameter needs a 5/32 inch hole and ¼ inch diameter needs a 3/16 inch hole. The screw also has special threads for efficient dust removal.

“The CONFAST hex head concrete screw can now be purchased online, direct from the manufacturer, for a saving of up to 70% over retail pricing. This easy to install screw works wells in concrete, brick or block, and is designed for indoor, dry applications,” states Bob Carlisle, president of Concrete Fastening Systems Inc.

Deputy Editor

Claire Aldridge Deputy Editor t: +44 (0) 1727 814 450


Having joined the magazine in 2012, Claire developed her knowledge of the industry through the numerous company visits, exhibitions and conferences she attended both in the UK and abroad.

Claire prides herself on keeping readers well informed and up to date with the latest industry news.