Design Eurotec Structural Wood Screws to the NDS

Eurotec (EUROTEC GmbH, Hagen, Germany) manufactures structural wood screws for timber construction. In the US, their screws are recognized under ICC-ES ESR-3942, which publishes reference design values for use with the ANSI/AWC NDS under the IBC and IRC. SPEC Toolbox designs the screws using those values, in both ASD and LRFD design methodologies.

The US integration presents the three Eurotec families evaluated in ESR-3942, grouped by role.

Connection screws (partial thread)

• Paneltwistec, countersunk ribbed head (SK) or washer head (TK), star drive (1/4, 5/16 and 3/8 in.).
• SawTec, stepped flat head with teeth under the head, star drive (1/4, 5/16 and 3/8 in.).

Fully threaded screws

• KonstruX ST, cylindrical head (ZK) or countersunk ribbed head (SK), star drive, self-drilling tip (1/4, 5/16 and 3/8 in.).

The screws are hardened, galvanized carbon steel and install without a lead hole. Predrilling is optional and is recommended for dense species such as Douglas fir and for long screws, with the hole kept to no more than 0.9 times the root diameter. Diameters and lengths are as listed in ESR-3942.

At a glance, in the US scope the Eurotec families support:

• Wood-to-wood connections in sawn lumber, structural glued laminated timber, and the face of CLT panels.
• Withdrawal, head pull-through and lateral loading, and combined lateral-plus-withdrawal, designed per the NDS.
• Both ASD (allowable) and LRFD (design) methods.
• Dry service (member moisture content of 19 percent or less).

• Inclined installation, for KonstruX. ESR-3942 gives the fully threaded KonstruX ST screws a tabulated reduction factor for withdrawal when they are driven at an angle to the face (from 1.00 at 90 degrees down to 0.77 at 30 degrees), so angled and crossed-pair details can be designed directly, down to a spacing of 1.5 diameters between crossing screws. Inclined withdrawal for the Paneltwistec and SawTec screws is outside the report’s scope.
• A toothed flat head, for SawTec. The SawTec screw has a stepped flat head with teeth on its underside that seat into the side member, with its own tabulated head pull-through values.
• Recognized for the face of CLT. The report explicitly covers fixing into the face of CLT panels (all laminations meeting the tabulated specific gravity), not only sawn lumber and glulam.
• ASD and LRFD reference values, ready to apply. The integration carries the report’s reference values for both methods (screw tension and shear, withdrawal, head pull-through and lateral), tabulated across the NDS specific gravities from 0.35 to 0.55, so a connection can be checked directly against the assigned specific gravity of the members.

The Eurotec US screws are available in the Screw module and in the wood-to-wood connection detail calculators, worked in ASD or LRFD to the NDS:

• panel-to-panel joints (half-lap and spline);
• slab-to-wall, wall-to-wall and floor-to-wall.

Reference values are selected for the assigned specific gravity of the connected members, and end, edge and spacing requirements are applied per the NDS and the ESR-3942 geometry, including the separate predrilled and non-predrilled cases and the larger distances required in denser species such as Douglas fir.

Design follows the ANSI/AWC NDS under the IBC and IRC. ESR-3942 supplies reference (allowable and design) values in imperial units for withdrawal, head pull-through, lateral resistance and screw steel strength. These are adjusted by the applicable NDS factors for the chosen method, among them load duration, wet service, temperature, group action, geometry and end grain, to give allowable (ASD) or design (LRFD) values. Reference values are keyed to the member’s assigned specific gravity (per the NDS specific-gravity tables). The evaluation is for dry service (moisture content 19 percent or less); other engineered wood products, preservative or fire-retardant treated wood, and saltwater exposure are outside its scope. The screws were also evaluated to the 2022 California Building Code and Residential Code through the report’s California Supplement.