{"product_id":"fully-threaded-screw-vgz","title":"VGZ · Fully threaded cylindrical head screw","description":"\u003cp\u003eVGZ is a fully threaded structural screw with a cylindrical head, in electrogalvanised carbon steel. It is approved for structural applications subject to stresses in any direction to the grain, from 0 to 90 degrees.\u003c\/p\u003e\n\n\u003cp\u003eThe cylindrical head is the point of it. It lets the screw penetrate and pass through the surface of the timber rather than stopping on it, so the fixing goes away inside the member. That is what makes VGZ a reinforcement and coupling screw rather than a surface fastener, and it is why it suits concealed joints, timber couplings and structural reinforcement.\u003c\/p\u003e\n\n\u003ch2\u003eWhere it's used\u003c\/h2\u003e\n\u003cul\u003e\n  \u003cli\u003eReinforcement orthogonal to the grain, for hanging load where a secondary beam meets a main beam\u003c\/li\u003e\n  \u003cli\u003eSide-by-side joining of CLT floors, which the datasheet describes as very high stiffness\u003c\/li\u003e\n  \u003cli\u003eCoupling beams, in structural renovation and in new work\u003c\/li\u003e\n  \u003cli\u003eJoining small timber elements, such as the crossbeams and uprights of light frame structures\u003c\/li\u003e\n  \u003cli\u003eInstallation at double 45 degree inclination\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch2\u003eWhat it fixes into\u003c\/h2\u003e\n\u003cul\u003e\n  \u003cli\u003eTimber based panels\u003c\/li\u003e\n  \u003cli\u003eSolid timber\u003c\/li\u003e\n  \u003cli\u003eGlulam\u003c\/li\u003e\n  \u003cli\u003eCLT and LVL\u003c\/li\u003e\n  \u003cli\u003eHigh density woods\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003cp\u003eThe values for CLT and for high density woods such as Microllam LVL are tested, certified and calculated for those materials, not carried across from solid timber. The screw can also be used parallel to the grain.\u003c\/p\u003e\n\n\u003cp\u003eThe coating is electrogalvanised zinc, and that is what sets the working environment. VGZ is for service class 1 and 2, atmospheric corrosivity C1 to C2 and wood corrosivity T1 to T2. In plain terms, dry and covered work. It is not approved for external use, for unheated and damp conditions, or for coastal exposure. Service class 3 needs stainless steel or a zinc-aluminium flake coating, and this screw has neither.\u003c\/p\u003e\n\n\u003cp\u003eCyclic SEISMIC-REV testing has been carried out according to EN 12512 (VGZ technical data sheet, p.1). EN 12512 is a test method rather than a performance class. The European Technical Assessment covers connections under static and quasi-static loading, and seismic design of the connection stays with the project's structural engineer.\u003c\/p\u003e\n\n\u003ch2\u003eThe tip, and which screws have it\u003c\/h2\u003e\n\u003cp\u003eMost of the range has the 3 THORNS tip, which reduces the minimum installation distances. More screws fit in less space, and larger screws fit in smaller elements, which the datasheet gives as a reduction in the cost and time of project implementation. It is on every 7 mm screw, on 9 mm screws up to 520 mm long, and on 11 mm screws up to 600 mm long. The two longest 9 mm screws and the eight longest 11 mm screws have a different self-drilling tip instead, so the reduced distances are not theirs. Check the length before you rely on the spacing.\u003c\/p\u003e\n\n\u003ch2\u003eSizes\u003c\/h2\u003e\n\u003cp\u003eThree diameters. 7 mm runs from 80 to 400 mm, 9 mm from 160 to 600 mm, and 11 mm from 150 to 1000 mm. Drive is TX30, TX40 and TX50 respectively, and the bit is included.\u003c\/p\u003e\n\n\u003cp\u003eBox quantity is not the same across the range. Every 7 mm screw, and every 9 mm screw up to 400 mm, comes 50 to a box. From 9 mm at 440 mm upwards, and across the whole 11 mm range, the box holds 25. The pack quantity is shown on every row of the table below, so read it from the row rather than assuming one figure for the range.\u003c\/p\u003e\n\n\u003ch2\u003eBefore you fix\u003c\/h2\u003e\n\u003cul\u003e\n  \u003cli\u003eAbove a characteristic timber density of 550 kg per cubic metre the screw must be driven into a pre-drilled hole. This one is not on the datasheet. It comes from the European Technical Assessment, and VGZ is not on its list of exceptions\u003c\/li\u003e\n  \u003cli\u003ePre-drilling hole diameters are given for two cases and they are not the same. One is for softwood, the other for hardwood and beech LVL\u003c\/li\u003e\n  \u003cli\u003eThe screws are approved for connections under static or quasi-static loading\u003c\/li\u003e\n  \u003cli\u003ePull the elements together before the screws go in. The datasheet's method is to close the initial gap with a partially threaded screw first, then insert the VGZ, then take the temporary screw back out\u003c\/li\u003e\n  \u003cli\u003ePosition the screws to the minimum distances. They are given separately for axial stresses, for shear loads, for CLT and for LVL, and separately again for installation with and without a pre-drilled hole. Do not read one case off another case's table\u003c\/li\u003e\n  \u003cli\u003eA row of screws does not give you the sum of the individual capacities. The datasheet gives an effective number to apply, both for screws in a row parallel to the grain and for pairs of crossed screws\u003c\/li\u003e\n  \u003cli\u003eThe 45 degree applications rely on getting the angle right. The datasheet's method is to hold the angle for the first third of the drive, then finish without the guide\u003c\/li\u003e\n  \u003cli\u003eDimensioning and verification of the timber elements is carried out separately, and instability of the connectors is verified separately\u003c\/li\u003e\n  \u003cli\u003eThe assumed working life is 50 years. The European Technical Assessment states plainly that this is an assumption made for the assessment, not a guarantee\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch2\u003eDesign and specification support\u003c\/h2\u003e\n\u003cp\u003eThe characteristic values, the minimum distances and the effective number tables are all in the Specifications tab and the linked datasheet. This is product-selection guidance. Final loads, quantities, spacing and sign-off must be confirmed by the customer's qualified structural engineer against the product ETA. See also our \u003ca href=\"\/blogs\/insights\/eurocode-5-explained-timber-design-uk\"\u003eguide to Eurocode 5 timber design\u003c\/a\u003e, our \u003ca href=\"\/pages\/services\"\u003estructural engineering support\u003c\/a\u003e, and the full \u003ca href=\"\/collections\/screws-for-timber\"\u003estructural timber screw range\u003c\/a\u003e.\u003c\/p\u003e\n\n\u003cp\u003e\u003cem\u003ePrice shown is per box. The box holds 50 or 25 depending on the code, so check the pack quantity on the row. The table below gives codes, diameters, lengths and pack quantity.\u003c\/em\u003e\u003c\/p\u003e","brand":"Rothoblaas","offers":[{"title":"7 mm \/ 80 mm","offer_id":55234815033686,"sku":"VGZ780","price":18.0,"currency_code":"GBP","in_stock":true},{"title":"7 mm \/ 100 mm","offer_id":55234815066454,"sku":"VGZ7100","price":20.5,"currency_code":"GBP","in_stock":true},{"title":"7 mm \/ 120 mm","offer_id":55234815099222,"sku":"VGZ7120","price":25.5,"currency_code":"GBP","in_stock":true},{"title":"7 mm \/ 140 mm","offer_id":55234815131990,"sku":"VGZ7140","price":31.5,"currency_code":"GBP","in_stock":true},{"title":"7 mm \/ 160 mm","offer_id":55234815164758,"sku":"VGZ7160","price":38.0,"currency_code":"GBP","in_stock":true},{"title":"7 mm \/ 180 mm","offer_id":55234815197526,"sku":"VGZ7180","price":45.0,"currency_code":"GBP","in_stock":true},{"title":"7 mm \/ 200 mm","offer_id":55234815230294,"sku":"VGZ7200","price":52.5,"currency_code":"GBP","in_stock":true},{"title":"7 mm \/ 220 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