Design Rothoblaas Screws to Eurocode 5

Rothoblaas has supplied the timber construction sector from its base in the Alpine region since 1991, with fastening systems alongside waterproofing, soundproofing and fall protection. The screws integrated here are its European structural range, assessed under ETA-11/0030.

Eighteen screw families are integrated for the European market, seventeen of them assessed under ETA-11/0030 and grouped by product line.

• Countersunk head: HBS (3.5-12 mm, 30-1000 mm), HBS EVO (4-8 mm, 40-320 mm) and HBS Hardwood (6-8 mm, 80-480 mm).
• Flange head: TBS (6-12 mm, 40-1000 mm), TBS EVO (6-10 mm, 60-400 mm), TBS Frame (8 mm, 73-175 mm, short thread) and TBS MAX (8 mm, 120-400 mm, long thread).
• Full thread: VGS (9-13 mm, 80-1500 mm), VGS EVO (9-15 mm, 100-800 mm), VGZ (7-11 mm, 80-1000 mm), VGZ EVO (5-11 mm, 80-600 mm) and VGZ Hardwood (6-8 mm, 140-440 mm).
• Plate screws: LBS (5-7 mm, 25-100 mm), LBS EVO (5-7 mm, 40-100 mm), LBS Hardwood (5 mm, 40-70 mm), HBS Plate (8-12 mm, 60-200 mm), HBS Plate EVO (5-12 mm, 40-200 mm) and VGS Plate (11mm, 60-280mm).

The nineteenth family, the KOP coach screw to DIN 571 (8-16 mm, 50-400 mm), is CE marked to EN 14592 rather than assessed under the ETA, and is installed pre-drilled per EN 1995.

The screws are carbon steel in service classes 1 and 2, with the six EVO families carrying a Zn-Al flake coating that extends them to service class 3. Characteristic values are read from the integrated database for the specific article at calculation time, not interpolated from a family average.

• Solid timber, glulam, CLT and LVL substrates, in every family.
• Steel to timber connections, with the steel plate on the screw head side.
• CLT face fixing and CLT edge fixing.
• Insertion at an angle to the grain.
• Reinforcement, with the full thread families VGS, VGS EVO, VGZ, VGZ EVO and VGZ Hardwood.
• Service class 3 and exposed conditions, with the six EVO families.
• Hardwood connections, with HBS Hardwood, LBS Hardwood and VGZ Hardwood.

• Withdrawal and head pull-through parameters are carried per substrate rather than as one softwood value. The standard families hold 11.7 N/mm2 in softwood, 15.0 N/mm2 in non pre-drilled softwood LVL and 29.0 N/mm2 in pre-drilled beech LVL or FST. The hardwood families add 22.0 N/mm2 in non pre-drilled hardwood and 42.0 N/mm2 in non pre-drilled Beech LVL or FST, with head pull-through reaching 50 N/mm2 in Beech LVL.
• The full thread families used for reinforcement are verified in compression as the lesser of the push-in withdrawal capacity and a buckling capacity on an elastic foundation, with a foundation modulus that scales with diameter, characteristic density and the angle to the grain, and a characteristic yield strength of 1000 N/mm2 for the carbon steel screws.
• Screws arranged parallel to the plane of a CLT panel use a dedicated embedment strength and withdrawal capacity, both independent of the angle to the grain. Edge face spacings are 10 times the diameter parallel to grain and 4 times perpendicular, against 4 and 2.5 times the diameter on the wide face.
• In steel to timber connections using LBS or LBS Hardwood at 5 mm diameter, a steel plate of 1.5 mm or thicker may be taken as a thick plate, which changes the failure modes available to the connection.

Every family on this page is available in the Screw module and in the connection detail calculators: panel to panel (half lap, spline and butt joint), slab to wall, wall to wall, floor to wall. They also appear in the rib deck calculator, for flexible connection design to Eurocode 5. The five families marked for reinforcement also appear in the reinforcement connection details: beam notch, beam penetration, and beam compression perpendicular to grain.

Connection design follows EN 1995-1-1 clause 8.7, with clause 8.7.2 governing axially loaded screws. Clause 8.7.2(1)P lists buckling under compression among the failure modes, which is the check the ETA sets out for the full thread reinforcement screws. The ETA declares an inner to outer thread diameter ratio of 0.55 to 0.75. ETA-11/0030 supports CE marking for the European market. The same product data is used for design in the AUS and NZ markets in accordance with the applicable design standards there.