Tips on fastening wood flooring to concrete

CLEVELAND - Dec. 14, 2017 - PRLog -- No matter how many years in the business, professional floor installers find themselves faced with choices when installing a wood floor to concrete. There are two primary methods for attaching the subfloor to the concrete, which are using split drive anchors or tapcon masonry screws. The two methods have one thing in common: the head of the fastener once installed is flush with the surface of the subfloor. This is a critical consideration because it ensures that the finished floor will sit flat on the subflooring. The selected spacing of the fasteners will also rest upon on local codes, flooring manufacturers' recommendations, and personal preference.

Using Split Drive Anchors
The split drive anchor is a one piece, fast and easy-to-install concrete anchor that comes with a flat countersunk head. Split drive anchors are called pre-expanded expansion anchors. The anchor is manufactured larger than the hole in the concrete that it will be installed in, and, once installed, exerts outward pressure trying to get back to its original shape.
Diameter - only ¼"; the hole size to be drilled in the concrete isequal to the diameter of the anchor - ¼".
Length - the length of a split drive anchor to use for fastening wood to concrete is determined by adding the thickness of the wood to the minimum embedment of 1-1/8". The split drive diameter is measured as an overall length that includes the head.
Anchor Spacing - the minimum distance between split drive anchors in the expansion anchor industry is 10 anchor diameters between anchors, or 2.5" and 5 anchor diameters, or 1-1/4" from an unsupported edge. The reason is that once set the split drive anchor is installed it exerts forces against the concrete, if the anchors are installed too close together then these forces may interact and reduce holding values.

Tapcon Masonry Screws
The Tapcon screw is a self-tapping concrete screw that taps threads into a predrilled hole in the concrete. Tapcon is the original American concrete screw with advanced threadform technology that requires less torque, making them easier to install. The Blue Climaseal™ provides extended corrosion resistance.
Head Style - tapcons come in two head styles; the flat Phillips countersunk style is the head style to use for putting subflooring down.
Diameter - available in the 3/16" diameter and ¼" diameter: the ¼" diameter provides greater holding value; most professional installers use the ¼" diameter.
Length - to determine the minimum length of Tapcon to use for any specific application add the minimum embedment depth of 1" to the thickness of the wood being attached. If a 2x4 is being used as a sleeper then add 1" to the 1-1/2" for a minimum length of 2-1/2". The closest Tapcon length over the 2-1/2" is 2-3/4". The maximum embedment for a Tapcon in theconcrete is 1-3/4", so the longest screw for this 2x application would be 1-3/4" plus 1-1/2" or 3-1/4". Therefore, the closest Tapcon to meet this requirement would be the 3-1/4" Tapcon.
Moisture conditions also add a critical element to the floor installation. Prior to installing a wood floor, the building should have been completely enclosed and have the windows, doors and sheetrock installed. Heating should be supplied for a minimum of five days before installation. If the weather is warm to hot, then the area must be well ventilated. Concrete must be a minimum of 30 days old. The surface of the concrete must be flat and free of oil, grease, and dust. Always use a moisture bearer, which is usually placed between the subfloor and the finished floor.
These tips are brought to you by Concrete Fastening Systems, where 80 million concrete fasteners have been packaged and shipped on the same business day an order was received. Over 4.7 million fasteners are stocked to provide customers with same-day shipping followed by free delivery within 1-3 days of purchase.

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